03llc(link layer protocol configuration guide)

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User Manual -Configuration Guide (Volume 1)Versatile Routing Platform Table of Contents

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Table of Contents

Chapter 1 Configuring PPP and MP .................................................................................... 1-1

1.1 PPP and MP Overview..............................................................................................1-1

1.1.1 PPP Overview........ ........ ......... ......... ........ ......... ........ ......... ........ ......... ........ .... 1-1

1.1.2 MP Overview ..................................................................................................1-2

1.2 Configuring PPP....................................................................................................... 1-3

1.2.1 PPP Configuration Task List ........ ......... ........ ......... ......... ........ ......... ........ ........ 1-3

1.2.2 Configuring the Link Layer Protocol for Interface Encapsulation as PPP........ ..... 1-3

1.2.3 Configuring PPP Authentication Mode, Username and User Password.......... ..... 1-3

1.2.4 Configuring AAA Authentication and Accounting Parameter of PPP............ ........ 1-5

1.2.5 Configuring PPP Negotiation Parameter....... ......... ........ ......... ........ ......... ........ . 1-5

1.2.6 Configuring PPP Compression.. ......... ......... ........ ......... ........ ......... ........ ......... .. 1-6

1.3 Configuring MP......................................................................................................... 1-6

1.3.1 MP Configuration Task List...... ......... ........ ......... ........ ......... ........ ......... ........ .... 1-6

1.3.2 Configuring MP on Virtual Interface Template ......... ......... ........ ......... ........ ........ 1-7

1.4 Monitoring and Maintenance of PPP ........ ........ ......... ........ ......... ......... ........ ......... ...... 1-7

1.5 Typical PPP Configuration Example......... ........ ......... ........ ......... ......... ........ ......... ...... 1-8

1.5.1 PAP Authentication Example ........................................................................... 1-8

1.5.2 CHAP Authentication Example....... ........ ......... ........ ......... ......... ........ ......... ...... 1-9

1.6 Typical MP Configuration Example........ ........ ......... ......... ........ ......... ........ ......... ....... 1-10

1.7 Fault Diagnosis and Troubleshooting of PPP......... ........ ......... ........ ......... ........ ......... 1-12

Chapter 2 Configuring SLIP.............. ........ ......... ........ ......... ........ ......... ......... ........ ......... ...... 2-1

2.1 SLIP Overview.......................................................................................................... 2-1

2.2 Configuring SLIP....................................................................................................... 2-1

2.2.1 SLIP Configuration Task List.............. ......... ........ ......... ........ ......... ........ ......... .. 2-1

2.2.2 Configuring the Sync/Async Serial Interface to Work in Async Mode.............. ..... 2-1

2.2.3 Configuring Encapsulation Protocol SLIP......... ........ ......... ......... ........ ......... ...... 2-2

2.3 Monitoring and Maintenance of SLIP........ ........ ......... ........ ......... ......... ........ ......... ...... 2-2

2.4 Typical SLIP Configuration Example......... ........ ......... ........ ......... ......... ........ ......... ...... 2-2

Chapter 3 Configuring ISDN Protocol... ........ ......... ......... ........ ......... ........ ......... ........ ......... .. 3-1

3.1 ISDN Protocol Overview.............. ......... ........ ......... ......... ........ ......... ........ ......... ........ . 3-1

3.2 Configuring ISDN...................................................................................................... 3-1

3.2.1 ISDN Configuration Task List.... ......... ......... ........ ......... ........ ......... ........ ......... .. 3-1

3.2.2 Setting the Called Number or Sub-Address to be Checked......... ........ ......... ...... 3-1

3.3 Monitoring and Maintenance of ISDN Configuration ......... ........ ......... ........ ......... ........ . 3-2

3.4 Typical ISDN Configuration Example......... ......... ........ ......... ........ ......... ........ ......... ..... 3-4

3.5 Fault Diagnosis and Troubleshooting of ISDN............... ........ ......... ........ ......... ........ .... 3-5




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Chapter 4 Configuring LAPB, X.25 and X.25 Switching... ......... ........ ......... ........ ......... ........ . 4-1

4.1 X.25 and LAPB Protocols Overview ......... ........ ......... ........ ......... ......... ........ ......... ...... 4-1

4.2 Configuring LAPB .....................................................................................................4-3

4.2.1 LAPB Configuration Task List ........ ........ ......... ........ ......... ......... ........ ......... ...... 4-3

4.2.2 Configuring Encapsulation LAPB Protocol........ ........ ......... ......... ........ ......... ...... 4-3

4.2.3 Configuring LAPB Protocol Parameter................ ........ ......... ........ ......... ........ .... 4-4

4.3 Configuring X.25 ....................................................................................................... 4-5

4.3.1 X.25 Configuration Task List..... ......... ......... ........ ......... ........ ......... ........ ......... .. 4-5

4.3.2 Configuring X.25 Interface ........ ......... ......... ........ ......... ........ ......... ........ ......... .. 4-6

4.3.3 Configuring X.25 Interface Supplementary Parameter......... ......... ........ ......... ... 4-11

4.3.4 Configuring X.25 Datagram Transmission......... ......... ........ ......... ........ ......... ... 4-15

4.3.5 Configuring Additional Parameters of X.25 Datagram Transmission ........ ......... 4-16

4.3.6 Configuring X.25 Sub-Interface......... ........ ......... ........ ......... ........ ......... ........ .. 4-21

4.3.7 Configuring X.25 Switching......... ........ ......... ......... ........ ......... ........ ......... ....... 4-21

4.3.8 Configuring XOT........................................................................................... 4-24

4.4 Monitoring and Maintenance of LAPB, X.25 and X.25 Switching........ ........ ......... ....... 4-28

4.4.1 Displaying the Information of Interface Encapsulated LAPB ......... ........ ......... ... 4-29

4.4.2 Displaying the Information of Interface Encapsulated X.25 ........ ......... ........ ...... 4-30

4.4.3 Displaying X.25 Alias Table................ ......... ........ ......... ........ ......... ........ ......... 4-31

4.4.4 Displaying X.25 Address Mapping Table........ ......... ......... ........ ......... ........ ...... 4-32

4.4.5 Displaying X.25 Switching Route Table................ ......... ........ ......... ........ ......... 4-32

4.4.6 Displaying X.25 Virtual Circuit Table................ ........ ......... ......... ........ ......... .... 4-32

4.5 Typical LAPB Configuration Example..... ......... ........ ......... ......... ........ ......... ........ ...... 4-34

4.6 Typical X.25 Configuration Example... ......... ........ ......... ........ ......... ........ ......... ........ .. 4-35

4.6.1 Back to Back Direct Connection of Two Routers via Serial Ports........ ........ ...... 4-35

4.6.2 Connecting the Router to X.25 Public Packet Network ........ ......... ........ ......... ... 4-36

4.6.3 Configuring Virtual Circuit Range.............. ........ ......... ........ ......... ........ ......... ... 4-38

4.6.4 Transmitting IP Datagram via X.25 PVC........ ......... ......... ........ ......... ........ ...... 4-39

4.6.5 Typical X.25 Sub-Interface Configuration Example......... ......... ........ ......... ....... 4-41

4.6.6 SVC Application of XOT........ ......... ........ ......... ........ ......... ......... ........ ......... .... 4-42

4.6.7 PVC Application of XOT........ ......... ........ ......... ........ ......... ......... ........ ......... .... 4-44

4.7 Fault Diagnosis and Troubleshooting of LAPB ........ ......... ........ ......... ........ ......... ....... 4-46

4.8 Fault Diagnosis and Troubleshooting of X.25......... ........ ......... ........ ......... ........ ......... 4-46

Chapter 5 Configuring Frame Relay.................................................................................... 5-1

5.1 Frame Relay Protocol Overview... ......... ........ ......... ......... ........ ......... ........ ......... ........ . 5-1

5.2 Configuring Frame Relay........ ........ ......... ........ ......... ........ ......... ......... ........ ......... ...... 5-2

5.2.1 Frame Relay Configuration Task List............ ......... ........ ......... ........ ......... ........ . 5-2

5.2.2 Configuring Interface Encapsulation as Frame Relay...... ......... ........ ......... ........ . 5-2

5.2.3 Configuring Frame Relay Terminal Type...... ........ ......... ........ ......... ........ ......... .. 5-3

5.2.4 Configuring Frame Relay LMI Type.... ......... ........ ......... ........ ......... ........ ......... .. 5-3

5.2.5 Configuring Frame Relay LMI Protocol Parameters ........ ......... ........ ......... ........ . 5-4

5.2.6 Configuring Frame Relay Address Mapping..... ........ ......... ......... ........ ......... ...... 5-6




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5.2.7 Configuring Frame Relay Local Virtual Circuit ......... ......... ........ ......... ........ ........ 5-7

5.2.8 Configuring Frame Relay Sub-Interface.. ......... ........ ......... ......... ........ ......... ...... 5-7

5.2.9 Configuring Frame Relay PVC Switching ......... ........ ......... ......... ........ ......... ...... 5-9

5.2.10 Enable/Disable TCP/IP Header Compression on Interfaces ........ ......... ........ .... 5-9

5.3 Monitoring and Maintenance of Frame Relay ......... ........ ......... ........ ......... ........ ......... 5-10

5.4 Typical Frame Relay Configuration Example........ ......... ........ ......... ........ ......... ........ .. 5-13

5.4.1 Interconnecting LANs via Frame Relay Network ......... ........ ......... ........ ......... ... 5-13

5.4.2 Interconnecting LANs via Private Line ......... ........ ......... ........ ......... ........ ......... 5-14

5.5 Fault Diagnosis and Troubleshooting of Frame Relay........ ......... ........ ......... ........ ...... 5-15

Chapter 6 Configuring HDLC......... ........ ......... ........ ......... ......... ........ ......... ........ ......... ........ . 6-1

6.1 Configuring HDLC......... ......... ........ ......... ........ ......... ........ ......... ......... ........ ......... ...... 6-1

6.1.1 HDLC Configuration Task List............. ......... ......... ........ ......... ........ ......... ........ . 6-1

6.1.2 Encapsulating Interface with HDLC Protocol. ......... ........ ......... ........ ......... ........ . 6-1

6.1.3 Setting Keepalive Time Delay ........ ........ ......... ........ ......... ......... ........ ......... ...... 6-2

6.2 Monitoring and Maintenance of HDLC...... ........ ......... ........ ......... ......... ........ ......... ...... 6-2



User Manual - Configuration Guide (Volume 1)Versatile Routing Platform

Chapter 1Configuring PPP and MP

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Chapter 1 Configuring PPP and MP

1.1 PPP and MP Overview

1.1.1 PPP Overview

The Point-to-Point Protocol (PPP) provides a standard method for transporting multi-

protocol datagrams over point-to-point links. It has found wide application since it canprovide user authentication, support synchronous/asynchronous operations and canbe expanded easily.

PPP defines a whole set of protocols, including link control protocol (LCP), networkcontrol protocol (NCP) and authentication protocols (PAP and CHAP). Of them:

l Link Control Protocol is used to negotiate some parameters of the link and isresponsible for creating and maintaining the link.

l Network Control Protocol is used to negotiate the parameters of network layer protocol.

PPP authentication mode includes the following:

1) PAP authentication

PAP (Password Authentication Protocol) is a 2-way handshake authentication protocoland it sends the password in plaintext. The process of PAP authentication is as follows:

The requester repeatedly sends its username/password combination across the linkuntil the authenticator responds with an acknowledgment or until the link is broken. Theauthenticator may disconnect the link if it determines that the username/passwordcombination is not valid.

2) CHAP authentication

CHAP (Challenge-Handshake Authentication Protocol) is a 3-way handshake

authentication protocol and it only sends its username but not the password across thelink. The process of CHAP is as follows:

The authenticator sends some randomly generated messages to the requester (challenge), and at the same time it sends its own hostname to the requester.

When the requester receives the challenge, it will look for the user password according

to the authenticator’ s hostname and its own user list. If it finds the user in the user listwith the same name as the authenticator’ s hostname, the requester builds theresponse with its own password, serial number of message using MD5 algorithm, andsends the generated response and its own hostname to the authenticator (response).

After receiving the response from the requester, the authenticator does the same

encryption as the requester with the saved password, serial number of message usingMD5 algorithm. Then it compares the encryption result with the response fromrequester, and returns the response according to the comparison result (Acknowledgeor Not Acknowledge).

Phases of PPP negotiation:

3) When the physical layer is unavailable, the link is in Dead phase. A link shall starts

from and end at the Dead phase. When the physical layer becomes available,PPP link enters the Establish phase.





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4) In Establish phase, PPP link carries out LCP negotiation, including negotiation of working mode (SP or MP), authentication mode and maximum transmission unitetc. After the successful LCP negotiation, the status of LCP is Open, indicatingthat the link has been established.

5) If the authentication is not configured, it begins NCP negotiation. At this time, thestatus of LCP is still Open, while the status of NCP is changed from Initial toRequest-sent. Then it enters the flow of step 5. If the authentication is configured(the remote verifies the local or the local verifies the remote), it enters Authenticatephase to start CHAP or PAP authentication, and then enters the flow of step 4.

6) If the authentication fails, it enters Terminate phase, the link is removed and LCPturns to Down. After successful authentication, the NCP negotiation begins. At thistime, the status of LCP is still Open, while the status of NCP is changed from Initialto Request-sent.

7) NCP negotiation supports the negotiations of IPCP and IPXCP, of which IPCPnegotiation mainly includes the IP addresses of two partners. One or morenetwork layer protocols is selected and configured through NCP negotiation. Theselected network layer protocol must be configured successfully before this

network layer protocol sends messages through this link.8) PPP link will remain in communication status until a specific LCP or NCP frame

closes this link or some external events take place (for example, the intervention of user).

Phases of PPP negotiation are shown in the following diagram.

Dead Establish Authenticate

Terminate Network

UP OPENED

FAIL FAIL

DOWN CLOSING

SUCCESS/NONE

Figure LLC-1-1 Diagram of PPP negotiation phases

For detailed description of PPP, refer to RFC1661.

1.1.2 MP Overview

MP (MultiLink PPP) provides load balancing functionality over multiple WAN links. At

the same time it provides multi-vendor interoperability, packet fragmentation andproper sequencing, and load calculation on both inbound and outbound traffic. MultilinkPPP allows packets to be fragmented. These fragments can be sent at the same timeover multiple point-to-point links to the same remote address. Multilink PPP works over the following interface types (single or multiple) which can be configured to supportPPP encapsulation:

l Asynchronous/Synchronous serial interfacesl BRI interfacesl PRI interfacesl Dialer interfacesl Virtual interface template

The interface working process in MP mode is as follows (taking MP in the virtualinterface template as example):





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First, begin LCP negotiation with the peer, negotiating about ordinary LCP parametersand verify whether the interface of the peer works in MP mode. If the peer does notwork in MP mode, begin NCP negotiation and do not bundle MP.

Then begin PPP authentication, and get the username of the peer. If the peer alsoworks in MP mode, locate the virtual interface template specified for the peer accordingto its username, and then begin NCP negotiation with the NCP parameters of thisvirtual template (such as IP address). The NCP parameters configured at the physicalinterface are not functional. If NCP negotiation is successful, MP link can beestablished, to transport data with wider bandwidth.

1.2 Configuring PPP

1.2.1 PPP Configuration Task List

PPP configuration task list is as follows:

l Configure the link layer protocol for interface encapsulation as PPPl Configure PPP authentication mode, username and user passwordl Configure AAA authentication and accounting parameter of PPPl Configure PPP negotiation parameter l Configure PPP compression algorithm

1.2.2 Configuring the Link Layer Protocol for Interface Encapsulation as PPP

Perform the following configuration in the interface configuration mode.

Table LLC-1-1 Configure the link layer protocol for interface encapsulation as PPP

Operation Command

Configure the link layer protocol for interface encapsulation as PPP encapsulation ppp

The default link layer protocol for interface encapsulation is PPP.

1.2.3 Configuring PPP Authentication Mode, Username and User Password

PPP has two authentication modes:

l PAP mode

l CHAP modeGenerally speaking, CHAP authentication is securer.

The respective configuration steps of PAP authentication and CHAP authentication areas follows.

& Note:

In the PPP authentication commands introduced in this section, only user series commands are used inthe global configuration mode, all other commands are used in the interface configuration mode.





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I. Configuring the local authenticates the opposite router in PAP mode


Table LLC-1-2 Configure the local authenticates the peer in PAP mode

Operation Command

Configure the local authenticates the peer (in PAP mode) ppp authentication pap [callin ][ default |name-list ]

Cancel the configured PPP authentication, i.e. do not perform PPPauthentication

no ppp authentication

Add the username and password of the peer into the local user list user user password { 0 | 7 }password

II. Configuring the local authenticates the peer in CHAP mode


Table LLC-1-3 Configure the local authenticates the peer in CHAP mode

Operation Command

Configure the local authenticates the peer (in CHAPmode)

ppp authentication chap [callin ] [default |name-list ]

Cancel the configured PPP authentication, i.e. do notperform PPP authentication

no ppp authentication

Configure the name of the local ppp chap host hostname

Delete the configured name of the local no ppp chap host

Add the username and password of the peer into thelocal user list

user user password { 0 | 7 }password

III. Configuring the peer authenticates the local in PAP mode


Table LLC-1-4 Configure the peer authenticates the local in PAP mode

Operation Command

Configure PAP username and password when the peer authenticates the local in PAP mode

ppp pap sent-username sent-usernamepassword { 0 | 7 }password

Delete the above configured username and password sentduring authentication in PAP mode

no ppp pap sent-username

IV. Configuring the peer authenticates the local in CHAP mode

Perform the following task in the interface configuration mode.





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Table LLC-1-5 Configure as the peer authenticates the local in CHAP mode

Operation Command

Configure the name of the local ppp chap host hostname

Delete the configured name of the local no ppp chap host

Configure the password of the local for authentication inCHAP mode

ppp chap password { 0 | 7 } password

Delete the password of the local during authentication inCHAP mode

no ppp chap password

Add the username and password of the peer into the localuser list

user user password { 0 | 7 }password

Generally speaking, in the situation that the router has configured user list, it configure

the command ppp chap host hostname and user user password { 0 | 7 } password, to

perform CHAP authentication. When configuring CHAP authentication, user of one endis the hostname of the other, and the password must be the same.

In some situation, the router cannot configure user list, then it need to configure thecommand ppp chap password { 0 | 7 } password to perform CHAP authentication.

1.2.4 Configuring AAA Authentication and Accounting Parameter of PPP

Whether the PPP user passes the authentication will be finally decided by AAA, whichcan authenticate PPP user at local or at RADIUS server.

Local authentication is to authenticate using the local user configured with the user

user password { 0 | 7 } password command, and RADIUS server authentication is toauthenticate with the user database on RADIUS server. The specific configuration

commands are shown in the following table.

Table LLC-1-6 Configure AAA authentication and accounting of PPP

Operation Command

Enable AAA aaa-enable

Configure PPP authentication method of AAA aaa authentication ppp { default | list-name }[ method1 | method2| ...... ]

Configure the local first authentication of AAA aaa authentication l ocal-first

Configure PPP authentication method of AAA at theinterface

ppp authentication { chap | pap } [ default

|list-name]

Configure accounting method list of PPP user of AAA at theinterface. At present the RADIUS authentication issupported.

ppp accounting { default | list-name }

For PPP authentication method of AAA, refer to the “ Security Configuration” part. If PPP authentication method of AAA is not specified on the interface, please use thedefault authentication method.

1.2.5 Configuring PPP Negotiation Parameter

The following PPP negotiation parameters can be configured:

l Time interval between negotiation timeout





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During PPP negotiation, if the response message of the peer is not received within thistime interval, PPP will redirect the message. The default time interval of timeout is 10s,and the value range is 1~10s.

l Some negotiation parameters of NCP

For the configuration of local IP address and the IP address assigned to the peer, refer to the “ Network Protocol Configuration” part in this manual. For example, the ip

address negotiate command can be used to require the peer to assign IP address for the local, while the peer default ip address command can be used to designate thelocal to assign IP address for the peer.

Table LLC-1-7 Configure the time interval of PPP negotiation timeout

Operation Command

Configure the time interval of negotiation timeout ppp n egotiate timeout seconds

Restore the default of time interval of negotiation timeout no ppp negotiate timeout

1.2.6 Configuring PPP Compression

The current VRP version supports the Stac compression method.


Table LLC-1-8 Configure PPP compression

Operation Command

Configure as Stac compression permitted on the interface ppp compress stac

Cancel the Stac compression used by the interface no ppp compress stac

& Note:

In MP working mode, it is not recommended to use PPP compression. To configure PPP compressionnegotiation on the virtual interface, PPP compression must be configured on Virtual-template interfacebefore the subordinate physical interface can accept the PPP compression negotiation.

1.3 Configuring MP

1.3.1 MP Configuration Task List

MP configuration tasks on the virtual interface template is shown as follow, the MPconfiguration in the DDR mode (including MP on the ISDN BRI/PRI interface) refers tothe “DDR Configuration” part of this manual.

l Create and configure MP virtual interface templatel Establish the corresponding relation between PPP user and MP virtual interface

templatel Configure the interface bound under the virtual interface template to work in MP

model Configure the authentication mode of virtual interface

l Configure maximum numbers of links and fragments that MP permits





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1.3.2 Configuring MP on Virtual Interface Template

Perform the following task to configure MP on virtual interface template.

Table LLC-1-9 Configure MP under MP virtual interface template

Operation Command

In global configuration mode, create and enter the MP virtualinterface template

interface virtual-template number

In virtual interface configuration mode, configure the workingparameter of the virtual interface template

Omitted

In global configuration mode, establish the corresponding relationbetween virtual interface template and PPP user

multilink-user user-name bind virtual-template

number

In global configuration mode, configure MP parameter multilink { max-binds binds | max-fragsfrags }

Note that before configuring MP, the virtual interface template must be configured andplease refer to "Virtual-Template and Virtual Interface" for specific configuration method.The interface bound under the virtual interface template shall perform two-wayauthentication with the remote end (CHAP or PAP). For configuring the workingparameters of the virtual interface template in the above table, please refer to “ Virtual-Template and Virtual Interface” .

1.4 Monitoring and Maintenance of PPP

Perform the following task in the privileged mode to monitor and maintain PPP.

Table LLC-1-10 Monitoring and maintenance of PPP

Operation Command

Show local user of PPP authentication show user

Show PPP configuration and running state of the interface show interface interface-type interface-number

1) Show the local user of PPP authentication.

Quidway# show user

No. username logintimes failedtimes-------------------------------------------------------------------

1 RTB_A 0 0 2 RTB_B 0 0

2) Show the PPP configuration and running state of the interface.

Quidway# show interface serial 0

Serial0 is up, line protocol is upphysical layer is synchronousinterface is DTE, clock is DTECLK1, cable type is V35Internet address is 10.3.0.158 255.255.255.252Encapsulation is PPPLCP opened, IPCP opened5 minutes input rate 1023.79 bytes/sec, 5.50 packets/sec5 minutes output rate 4836.88 bytes/sec, 5.92 packets/sec1005453 packets input, 488212969 bytes, 0 no buffers1833530 packets output, 547917333 bytes, 0 no buffers

1172162 input errors, 437770 CRC, 504267 frame errors





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0 overrunners, 230125 aborted sequences, 0 input no buffers

The above information includes the current states of LCP and IPCP, by which the user can estimate PPP running status.

1.5 Typical PPP Configuration Example

1.5.1 PAP Authentication Example

I. Configuration requirement

As shown in Figure LLC-1-2, routers Quidway1 and Quidway2 are interconnected

through interface Serial0, and router Quidway1 (authenticator) is required toauthenticate router Quidway2 (requester) in PAP mode.

II. Networking diagram

Quidway 2Quidway 1

Figure LLC-1-2 Networking diagram of PAP and CHAP authentication example

III. Configuration procedure

1) Configure router Quidway1 (authenticator):

! Add a user with name quidway2 and password hello to the local database

Quidway(config)# user quidway2 password 0 hello

! Configure to start PAP authentication at this side

Quidway(config)# interface serial 0

Quidway(config-if-Serial0)# ppp authentication pap

2) Configure router Quidway2 (requester):

! Configure this side to be authenticated by the opposite side with username quidway2and password hello


Quidway(config-if-Serial0)# ppp pap sent-username quidway2 password 0 hello

While configuring PAP authentication, note following things:

1) If one side originates the PAP, it (authenticator) should add username and

password for the requester in the local database ( user ...). The requester should

send its username and password to the authenticator ( ppp pap sent-

username....).2) If one side originates the PAP, it (authenticator) only needs to start PAP

authentication itself ( ppp authentication pap) . The requester does not need toconfigure the command.





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3) If both sides originate PAP simultaneously, then each side is both authenticator and requester. At this time, both sides need to configure all the commandssupporting the PAP authentication.

1.5.2 CHAP Authentication Example


In Figure LLC-1-2, router Quidway1 is required to authenticate router Quidway2 inCHAP mode.

II. Configuration procedure

1) Configure router Quidway1:



! Set local username as quidway1


Quidway(config-if-Serial0)# ppp chap host quidway1

! Configure to start CHAP authentication at this side

Quidway(config-if-Serial0)# ppp authentication chap

2) Configure router Quidway2:



! Set local username as quidway2


Quidway(config-if-Serial0)# ppp chap host quidway2

While configuring CHAP authentication, note following things:

1) If one side originates the CHAP, it (authenticator) should add username andpassword for the requester in the local database ( user ...), and should send its

username to the requester (ppp chap host...). The requester should also addusername and password for the authenticator in its database (user ...), and sendits username and password to the authenticator (ppp chap host...).

2) If one side originates the CHAP, it (authenticator) only needs to start CHAPauthentication itself ( ppp authentication chap) . The requester does not need toconfigure the command.

3) If both sides originate CHAP simultaneously, then each side is both authenticator and requester. At this time, both sides need to configure all the commandssupporting the CHAP authentication.





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1.6 Typical MP Configuration Example


In Figure LLC-1-3, two B channels of E1 interface of router-a are bound to the Bchannel of router-b, and the other two B channels are bound to router-c. Supposing thatfour B channels on router-a are serial2:1, serial2:2, serial2:3 and serial2:4, the namesof interfaces of two B channels on router-b are serial2:1 and serial2:2, and the namesof interfaces of two B channels on router-c are serial2:1 and serial2:2.


router-a

router-b

router-c

DDNTower System

Desktop System

Tower System

Desktop System

Tower System

Desktop System

Figure LLC-1-3 Networking diagram of MP configuration example


1) Configure router-a:

! Add a user for router-b and router-c respectively

Quidway(config)# user router-b password 0 router-b

Quidway(config)# user router-c password 0 router-c

! Specify the virtual interface templates for the two users and begin PPP negotiation for

the NCP information using this template

Quidway(config)# multilink-user router-b bind virtual-template 1

Quidway(config)# multilink-user router-c bind virtual-template 2

! Configure virtual interface template

Quidway(config)# interface virtual-template 1

Quidway(config-if-vitual-template1)# ip address 202.38.166.1 255.255.255.0


Quidway(config-if-vitual-template2)# ip address 202.38.168.1 255.255.255.0





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! Add the interfaces serial2:1, serial2:2, serial2:3 and serial2:4 into MP channel. Here,take serial2:1 as an example, and other interfaces are configured similarly.

Quidway(config)# interface serial 2:1

Quidway(config-if-Serial2: 1)# encapsulation ppp

Quidway(config-if-Serial2: 1)# ppp multilink

Quidway(config-if-Serial2:1)# ppp authentication pap

Quidway(config-if-serial2:1)# ppp pap sent-username router-a password 0 router-a

2) Configure router-b:

! Add a user for router-a

Quidway(config)# user router-a password 0 router-a

! Specify the virtual interface template for this user and begin PPP negotiation for theNCP information using this template

Quidway(config)# multilink-user router-a bind virtual-template 1

! Configure working parameters of the virtual interface template


Quidway(config-if-virtual-template1)# ip address 202.38.166.2 255.255. 255.0

! Add the interfaces serial2:1 and serial2:2 into MP channel. Here, take serial2:1 as anexample, and configure other interfaces similarly

Quidway(config)# interface serial2: 1

Quidway(config-if-serial2: 1)# ppp multilink

Quidway(config-if-serial2: 1)# ppp authentication pap

Quidway(config-if-serial2: 1)# ppp pap sent-username router-b password 0 router-b

3) Configure router-c:

! Add a user for router-a

Quidway(config)# user router-a password 0 router-a

! Specify the virtual interface template for this user and begin PPP negotiation for theNCP information using this template

Quidway(config)# multilink-user router-a bind virtual-template 1

! Configure working parameters of the virtual interface template


Quidway(config-if-virtual-template1)# ip address 202.38.168.2 255.255. 255.0

! Add the interfaces serial2:1 and serial2:2 into MP channel. Here, take serial2: 1 as anexample, and other interfaces are configured similarly.

Quidway(config)# interface serial2: 1

Quidway(config-if-serial2: 1)# ppp multilink

Quidway(config-if-serial2: 1)# ppp authentication pap

Quidway(config-if-serial2: 1)# ppp pap sent-username router-c password 0 router-c





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1.7 Fault Diagnosis and Troubleshooting of PPP

I. Fault 1: Link always fails to turn to up status.

Troubleshooting: It's possible that PPP authentication parameter is not configuredcorrectly, resulting in the failure of PPP authentication.

Turn on the debugging switch of PPP, and it is shown that LCP negotiation is successfuland turns to Up status, then begin PAP or CHAP negotiation and LCP turns to Downstatus.

II. Fault 2: Physical link fails to turn to up status.

Troubleshooting: Execute show interface serial interface-number command to viewthe current interface status, including five statuses:

serial number is administratively down, line protocol is down

It indicates that the interface is shut down.

serial number is down, line protocol is down

It indicates that the interface is not activated or the physical layer does not turn to Upstatus.

serial number is up, line protocol is up(spoofing)

It indicates that this interface is a dialup interface and the call is not connectedsuccessfully.

serial number is up, line protocol is up

It indicates that data can be transmitted through this interface.

serial number is up, line protocol is down

It indicates that this interface is activated, but link negotiation is not successful.




Chapter 2Configuring SLIP

2-1

Chapter 2 Configuring SLIP

2.1 SLIP Overview

SLIP (Serial Line Internet Protocol) defines a method of sending packets over standardRS-232 asynchronous serial lines.

SLIP is an inexpensive way of connecting PCs to a network. SLIP can be used over asynchronous dial-up modems, allowing computers in people's homes to be connectedto a network without the cost of a leased line. Besides, SLIP is easy to realize becauseit does not provide address, error detection, correction and compression algorithm.

& Note:

SLIP does not distinguish between different types of messages, so it supports only one type of networkprotocol at one time.

For details about SLIP, users can refer to RFC1055.

2.2 Configuring SLIP

2.2.1 SLIP Configuration Task List

Because SLIP protocol does not negotiate name of the remote end, SLIP dialer canonly be used with the standard DDR; meanwhile, SLIP can be encapsulated only on thephysical port, and can not be encapsulated on Dialer port.

Configure SLIP dialer on the physical port:

l Configure the synchronous/asynchronous serial interface to asynchronous model Configure the incoming and outgoing call authorities of Modeml Enable DDRl Configure encapsulation protocol SLIP

l Configure Dialer Group and Dialer List of activated callsl Configure the dial string of interface

For the specific configuration methods of DDR, Modem and Dialer, please refer torelated chapters of DDR, Modem.

2.2.2 Configuring the Sync/Async Serial Interface to Work in Async Mode






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Table LLC-2-1 Configure the synchronous/async serial interface to work in async mode

Operation Command

Configure the synchronous/asynchronous serial interface to work in asynchronousmode physical-layer async

By default, the synchronous/asynchronous serial interface operates in synchronousmode

2.2.3 Configuring Encapsulation Protocol SLIP

Perform the following task in the asynchronous interface configuration mode.

Table LLC-2-2 Configure the link layer protocol for interface encapsulation as SLIP

Operation Command

Configure the link layer protocol for interface encapsulation as SLIP encapsulation sli p

By default, the link layer protocol encapsulated on the interface is PPP.

Note the following points:

1) The interface can be encapsulated with SLIP only when it operates in theasynchronous mode.

2) When LAPB, X.25, HDLC or Frame Relay is operating on the interface, thephysical attributes of the interface cannot be modified to asynchronous mode. Atthis time, you should first modify the link layer encapsulation of the interface to

PPP and then you may change the interface attribute to asynchronous mode.3) After the interface is encapsulated with SLIP, its upper layer still can carry IPprotocol.

2.3 Monitoring and Maintenance of SLIP

Perform the following task in privileged mode to monitor the current state of SLIP in realtime.

Table LLC-2-3 Enable/Disable the information debugging of SLIP

Operation Command

Enable the information debugging of SLIP packet debug slip packetDisable the information debugging of SLIP packet no debug slip packet

2.4 Typical SLIP Configuration Example

I. Networking requirement

Interconnect two Quidway routers via PSTN and run IP.





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PSTN

E t h e r n e t

E t h e r n e t

Router ARouter B

IP 10.110.0.18810003

IP 10.110.0.28810026

IP 129.102.0.1IP 129.103.0.1

Modem Modem

Figure LLC-2-1 Networking diagram of SLIP dialer


l Configure Quidway router A:! Configure Dialer List

Quidway(config)# dialer-list 1 protocol ip permit

! Configure the synchronous/asynchronous interface to asynchronous mode


Quidway(config-if-Serial0)# physical-layer async

! Configure IP address of synchronous/asynchronous interface

Quidway(config-if-Serial0)# ip address 10.110.0.1 255.0.0.0

! Configure the incoming and outgoing call authorities of Modem

Quidway(config-if-Serial0)# modem

! Enable DDR

Quidway(config-if-Serial0)# dialer in-band

! Configure the Dialer String to router B

Quidway(config-if-Serial0)# dialer string 8810026

! Encapsulate SLIP protocol

Quidway(config-if-Serial0)# encapsulation slip

! Specify Dialer Group

Quidway(config-if-Serial0)# dialer-group 1

! Configure the default route to Route B

Quidway(config)# ip route 0.0.0.0 0.0.0.0 10.110.0.2

l Configure Quidway router B:

! Configure Dialer List


! Configure the synchronous/asynchronous interface to asynchronous mode





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Quidway(config-if-Serial0)# physical-layer async

! Configure IP address of synchronous/asynchronous interface


! Configure the incoming and outgoing call authorities of Modem

Quidway(config-if-Serial0)# modem

! Enable DDR

Quidway(config-if-Serial0)# dialer in-band

! Configure the Dialer String to router A

Quidway(config-if-Serial0)# dialer string 8810003

! Encapsulate SLIP protocol

Quidway(config-if-Serial0)# encapsulation slip

! Specify Dialer Group

Quidway(config-if-Serial0)# dialer-group 1

! Configure the default route to Route A

Quidway(config)# ip route 0.0.0.0 0.0.0.0 10.110.0.1




Chapter 3Configuring ISDN Protocol

3-1

Chapter 3 Configuring ISDN Protocol

3.1 ISDN Protocol Overview

ISDN (Integrated Services Digital Network), developed from telephone integrateddigital network (IDN), provides end-to-end digital connection, so as to support widerange of services (including voice and non-voice services).

ISDN provides the user with a group of standard multifunctional user-network

interfaces. In ITU-T I.412 recommendations, two types of user-network interfaces arespecified: basic rate interface (BRI) and primary rate interface. The bandwidth of BRI is2B+D, and that of PRI is 30B+D or 23B+D. Here:

l B channel is a user channel, used to transmit the voice, data and other user information with the transmission rate 64kbit/s.

l D channel is a control channel and used to transmit the common channel signaling,controlling the calls on B channels of the same interface. The rate of D channel is64kbit/s (PRI) or 16kbit/s (BRI). ITU-T Q.921, the data link layer protocol of Dchannel, defines the rules by which the information is exchanged between layer-2 entities on the user-network interface through D channel. Meanwhile, it supportsthe access of layer-3 entity. ITU-T Q.931, the network layer protocol of D channel,provides methods to establish, maintain and terminate the network connectionbetween communication application entities.

3.2 Configuring ISDN

3.2.1 ISDN Configuration Task List

ISDN protocol configuration task includes:

l Set the called number or sub-address to be checked in digital incoming call.

3.2.2 Setting the Called Number or Sub-Address to be Checked

Table LLC-3-1 Set the called number or sub-address to be checked in digital incoming call

Operation Command

Set the called number or sub-address to be checked in digital incoming callisdn answer1 [called-party][:subaddress]

Cancel the called number or sub-address to be checked in digital incoming call no isdn answer1

Set the additional called number or sub-address to be checked in digitalincoming call

isdn answer2 [called-party][:subaddress]

Cancel the additional called number or sub-address to be checked in digitalincoming call

no isdn answer2

By default, no called number or sub-address is configured.

The two commands are used to set the items to be checked in the digital incoming call.If the sub-address is set, call of the opposite will be rejected when the sub-address isnot sent or is sent incorrectly. The above two commands are independent commands





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and function separately. An incoming call will be accepted as long as it satisfies one of the items.

3.3 Monitoring and Maintenance of ISDN ConfigurationIn privileged mode, execute the following command to monitor the current state of ISDN in real time.

Table LLC-3-2 Maintain and monitor ISDN

Operation Command

Show the current activated call information of ISDNinterfaceShow all the information or the information of specifiedinterface

show isdn active [ interface interface-type

interface-number ]

Show the called number and sub-address to be checked on

ISDN interfaceShow all the information or the information of specifiedinterface

show isdn answers [ interface interface-typeinterface-number ]

Show the current state of ISDN interfaceShow all the information or the information of specifiedinterface

show isdn status [ interface interface- type

interface-number ]

Show the value of ISDN timer show isdn timer

Enable the debugging of ISDN CCdebug isdn cc [ interface interface-typeinterface-number ]

Disable the debugging of ISDN CCno debug isdn cc [ interface interface-type

interface-number ]

Enable the debugging of ISDN q921 protocoldebug isdn q921 [ interface interface-typeinterface-number ]

Disable the debugging of ISDN q921 protocolno debug isdn q921 [ interface interface-type

interface-number ]Turn on the debugging of ISDN q931 protocol

debug isdn q931 [ interface interface-typeinterface-number ]

Disable the debugging of ISDN q931 protocolno debug isdn q931 [ interface interface-type

interface-number ]

! Show the current activated call information of ISDN interface

Quidway# show isdn active interface bri 0

Bri0 ___________________________________________________________________Channel Call Call Calling Calling Called calledInfo Property Type Number Subaddress Number subaddress__________________________________________________________________

B1 Digital Out 8810124B2 Analog In 8810118 380 8810150 2201

The information shown above indicates that currently there are two activated calls onthe ISDN Bri0 interface:

l The outgoing digital call from B1 channel to 8810124.l The incoming analog calls from the terminal with the number 8810118 and sub-

address 380 to B2 channel.

! Show the called number and sub-address to be checked on ISDN interface

Quidway# show isdn answers interface bri 0

Bri0:ISDN Answer1 66668888ISDN Answer2 :sub2000





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The information shown above indicates that in the case of incoming digital call on theinterface Bri0, the called number to be checked is 66668888, the sub-address to bechecked additionally is sub2000.

! Show the current status of ISDN interfaceQuidway# show isdn status interface bri 0

Bri0:Layer 2 Status:TEI = 64, State = MULTIPLE_FRAME_ESTABLISHEDLayer 3 Status:2 Active Layer 3 Call(s)CCIndex = 0x0001 , State = Setup , CES = 1 , Channel =0x00000002Calling_Num=661003,Calling_Sub=,Called_Num = 660066,Called_Sub =CCIndex = 0x0000,State = Active , CES = 1 , Channel = 0x00000001Calling_Num=661004,Calling_Sub=,Called_Num=660066 , Called_Sub =

The information shown above indicates that layer-2 link TEI of ISDN interface Bri0 is 64,and the status is that multiple frames are established. The number of active calls of

layer 3 is 2, the call with the index number 0x0001 is being set up, CES is 1, the channelis 0x00000002, the calling and called numbers are respectively 661003 and 660066,and both the calling and called sub-addresses are empty. The call with the indexnumber 0x0000 is active, CES is 1, the channel is 0x00000001, the calling and callednumbers are respectively 661004 and 660066, and both the calling and called sub-addresses are empty.

! Show the value of ISDN timer

Quidway# show isdn timer

ISDN Layer 2 values K = 1 Outstanding I-frames on BRI port N200 = 3 Max number of retransmits T200 = 1 Seconds T202 = 2 Seconds T203 = 10 SecondsISDN Layer 3 values T301 = 240 Seconds T302 = 15 Seconds T303 = 4 Seconds T304 = 30 Seconds T305 = 30 Seconds T308 = 4 Seconds T309 = 90 Seconds T310 = 10 Seconds T313 = 4 Seconds T314 = 4 Seconds T316 = 120 Seconds T317 = 10 Seconds T318 = 4 Seconds

T319 = 4 Seconds T321 = 30 Seconds T322 = 4 Seconds

& Note:

If there is only one type of ISDN interface (BRI or PRI) in the router, only the K value of correspondinginterface is shown.





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3.4 Typical ISDN Configuration Example


Router A is connected with router B via WAN, as shown in the following diagram.


Router A

ISDN switchingnetwork 8810154

cE1/PRI

202.38.154.2

202.38.154.1

8810152

cE1/PRI

Router B

Figure LLC-3-1 Networking diagram of ISDN protocol configuration example


l Configure Router A:

! Configure the timeslot binding of B channel of PRI interface

Quidway(config)# controller e1 0

Quidway(config-if-e1-0)# pri-group timeslots 1-31

Quidway(config-if-e1-0)# exit

! Configure D channel of PRI interface


! Configure IP address

Quidway(config-if-Serial2: 15)# ip address 202.38.154.1 255.255.0.0

! Configure dialer

Quidway(config-if-Serial2: 15)# dialer map ip 202.38.154.2 8810154

Quidway(config-if-Serial2: 15)# dialer-group 1

Quidway(config-if-Serial2: 15)# exit


l Configure Router B:

! Configure the timeslot binding of B channel of PRI interface

Quidway(config)# controller e1 0

Quidway(config-if-e1-0)# pri-group timeslots 1-31





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Quidway(config-if-e1-0)# exit

! Configure D channel of PRI interface


! Configure IP address

Quidway(config-if-Serial2: 15)# ip address 202.38.154.2 255.255.0.0

! Configure dialer

Quidway(config-if-Serial2: 15)# dialer map ip 202.38.154.1 8810152

Quidway(config-if-Serial2: 15)# dialer-group 1

Quidway(config-if-Serial2: 15)# exit


Either ping 202.38.154.2 on Router A or ping 202.38.154.1 on Router B can besuccessful.

3.5 Fault Diagnosis and Troubleshooting of ISDN

Fault: In the typical configuration example, cannot ping through the two routers.

Troubleshooting:

l Execute the command show isdn status and “ there is no isdn port” is displayed, itindicates that ISDN BRI or PRI port is not configured. Configure with the method inthe configuration example.

l If the information debugging of Q.921 is enabled and “ ISDN-D send data error” is

displayed, it indicates that the physical layer is not activated. Try the followingmethods to shut down and reopen the related interface:


Quidway(config-if-Serial2:15)# shutdown

Quidway(config-if-Serial2:15)# no shutdown

l For BRI interface, the corresponding process is as follows:

Quidway(config)# interface bri 0

Quidway(config-if-Bri0)# shutdown

Quidway(config-if-Bri0)# no shutdown

l Check whether the dialer is configured correctlyl If the dialer is configured correctly and no “ ISDN-D send data error” is displayed,

then it's possible the ISDN line is not connected well.




Chapter 4Configuring LAPB, X.25 and X.25 Switching

4-1

Chapter 4 Configuring LAPB, X.25 and X.25

Switching

4.1 X.25 and LAPB Protocols Overview

X.25 protocol is the interface procedure between the data terminal equipment (DTE)

and data circuit-terminating equipment (DCE). In 1974, CCITT issued the first draft of X.25, whose initial files were based on the experiences and recommendations of Telenet and Tymnet of USA and Datapac packet-switched networks of Canada. It wasrevised in 1976, 1978, 1980 and 1984, added many optional service functions andfacilities.

With X.25, two DTE can communicate with each other via the existing telephonenetwork. X.25 sessions are established when one DTE device contacts another torequest a communication session. The DTE device that receives the request can either accept or refuse the connection. If the request is accepted, the two systems beginfull-duplex information transfer. Either DTE device can terminate the connection. After the session is terminated, any further communication requires the establishment of anew session.

X.25 is the protocol of point-to-point interaction between DTE and DCE. DTE usuallyrefers to the host or terminal at the user side, and DCE usually refers to thesynchronous modem. DTE is connected with DCE directly, DCE is connected to a portof packet switching exchange, and some connections are established between the

packet switching exchanges, thus forming the paths between different DTE. In an X.25network, the relation between entities is shown in the following diagram:

DCEDTE

DCE

DCE

DTE

DTE

PSE

PSE

PSE

PSN

Figure LLC-4-1 X.25 network model

In the above figure, DTE stands for Data Terminal Equipment, DCE for Data Circuit-

terminating Equipment, PSE for Packet Switching Equipment, and PSN for PacketSwitched Network.

The X.25 protocol suite maps to the lowest three layers of the OSI (Open SystemInterconnection) reference model. The following protocols are typically used in X.25implementations: Packet-Layer Protocol (PLP), Link Access Procedure Balanced(LAPB), and those among other physical-layer serial interfaces. X.25 layer 3 (packet-layer protocol) describes the format of packet used by the packet layer and theprocedure of packet switching between two 3-layer entities. X.25 layer 2 (link-layer

protocol), also called LAPB (Link Access Procedure Balanced), defines the format and





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procedure of interactive frames between DTE and DCE. X.25 layer 1 (physical-layer protocol) defines some physical and electrical characteristics in the connectionbetween DTE and DCE. The above relation is shown in the following diagram.

OSI reference model

7

6

5

4

3

2

1

X.25

Packet layer interface

Link layer interface

Physical layer

interface

DTE DCE

X.25

Physical layer

X.25

Link layer

X.25

Packet layer

X.25

Physical layer

X.25

Link layer

X.25

Packet layer

Figure LLC-4-2 DTE/DCE interface

A virtual circuit is a logical connection created to ensure reliable communicationbetween two network devices. A virtual circuit denotes the existence of a logical, bi-directional path from one DTE device to another across an X.25 network. Two types of X.25 virtual circuits exist: permanent virtual circuit (PVC) and switched virtual circuit(SVC). PVCs are permanently established connections used for frequent andconsistent data transfers, whereas SVCs are temporary connections used for sporadic

data transfers.

Once a virtual circuit is established between a pair of DTEs, it is assigned with a uniquevirtual circuit number. When one DTE is to send a packet to the other, it numbers thispacket (with virtual circuit number) and sends it to DCE. According to the number onthe packet, DCE determines the method to switch this packet within the switchingnetwork, so that this packet can reach the destination. A link established between DTEand DCE by X.25 layer X.25 layer 3 multiplexes 2 (LAPB), and those finally presentedto users are several usable virtual circuits.

The relation between packets and frames in various X.25 layers is shown in thefollowing diagram.

Packet

header User data

DataFrameheader

FCSFramedelimiter

Bit stream

X.25 layer 3 Packet

X.25 layer 2 Frame

X.25 layer 1

Framedelimiter

Figure LLC-4-3 X.25 packet and LAPB frame

X.25 link layer specifies the frame switching process between DTE and DCE. In terms

of hierarchy, the link layer seems to bridge the packet layer interface of DTE and that of





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DCE. Through this bridge, the packets can be transmitted continuously between thepacket layer of DTE and that of DCE. The link layer has such main functions as follows:

l Transmit the data effectively between DTE and DCEl Ensure the synchronization of information between the receiver and transmitter l Detect and correct the error in the transmissionl Identify and report the procedure error to the higher layer protocoll Inform the packet layer of the link layer state

As specified in international standards, X.25 link layer protocol LAPB adopts the framestructure of high-level data link control (HDLC) and the frame structure is a subset of LAPB. The bi-directional link will be established when either site sends an SABM (Set Asynchronous Balanced mode) command and the other replies with UA.

Defined as X.25 layer-2 protocol, LAPB is actually a separate link layer protocol, whichcan transmit the data with LAPB bearing non-X.25 upper layer protocol. Quidway seriesrouter can directly employ LAPB protocol to encapsulate the serial port and performsimple local data transmission. Meanwhile, X.25 of Quidway series router hasswitching function, that is to say, the router can be used as a small X.25 packet switch.

The following diagram shows the relations among LAPB, X.25 and X.25 switching.

Inter-network protocol

X.25switching

X.25

LAPB

Figure LLC-4-4 Relations among LAPB, X.25 and X.25 switching

4.2 Configuring LAPB

4.2.1 LAPB Configuration Task List

To directly encapsulate the synchronous serial port as LAPB protocol, perform thefollowing configuration tasks:

l Configure encapsulation LAPB protocoll Configure LAPB protocol parameters

4.2.2 Configuring Encapsulation LAPB Protocol

In the interface configuration mode, perform the following task to configure the linklayer protocol encapsulated for interface as lapb.

Table LLC-4-1 Configure encapsulation LAPB protocol

Operation Command

Configure encapsulation LAPB protocol encapsulation lapb [dte |dce ] [ ip ]

If not specified, the working mode of LAPB is DTE by default. Besides, when LAPBprotocol is directly encapsulated, the upper layer protocol can be specified (IP issupported currently).





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4.2.3 Configuring LAPB Protocol Parameter

After specifying the encapsulation mode of LAPB, configure LAPB protocol parameter.

LAPB corresponds to the data link layer of OSI reference mode. LAPB specifiesmethods for exchanging data (frames), detecting out-of-sequence or missing frames,redirecting frames, and acknowledging frames. Several protocol parameters can bemodified to change LAPB protocol performance on a particular link. Modifyingparameters is mainly according to the indexes such as the reliability and delay of theconnection.

I. Configuring LAPB operating mode (also called modulo)

There are two LAPB modulos: Modulo 8 and Modulo128. Each data frame (I frame) isnumbered by sequence, the number can be any from 0 to modulo minus 1, and thesequence number is selected cyclically within the range of the modulo.

Modulo 8 (basic mode) is widely available because it is required for all standard LAPBimplementations and is sufficient for most links. Modulo128 (extended mode) canachieve greater throughput on high-speed links that have a low error rate by increasingthe number of frames that can be sent before the sending device must wait for acknowledgment (as configured by LAPB parameter K). The maximum value of LAPBwindow parameter K is modulo minus 1

In the interface configuration mode, configure as follows:

Table LLC-4-2 Configure LAPB frame numbering mode

Operation Command

Configure LAPB frame numbering mode (also called modulo) lapb modulo { 128 |8 }

By default, the LAPB modulos is Modulo 8.

II. Configuring LAPB parameter K

LAPB parameter K must be at most one less than the operating modulo. Modulo 8 linkscan send seven frames before an acknowledgment must be received by the sendingdevice; modulo 128 links can send as many as 127 frames. By default, LAPB links usethe basic mode with a window of 7.

In the interface configuration mode, configure as follows:

Table LLC-4-3 Configure LAPB window parameter K

Operation Command

Configure LAPB window parameter K lapb k k-value

Restore the default value of LAPB window parameter K no lapb k

By default, k is 7.

III. Configuring LAPB N1, N2

LAPB N1 is the maximum number of bits in a LAPB frame, which determines themaximum size of an X.25 packet. When you use LAPB over leased lines, the N1





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parameter should be eight times the hardware MTU size plus lapb protocol headlength.

The transmitting counter (N2) is the number of unsuccessful transmitting attempts thatare made before the link is declared down.

Table LLC-4-4 Configure LAPB N1, N2

Operation Command

Configure LAPB parameter N1 lapb n1

n1-value

Restore the default value of LAPB parameter N1 no lapb n1

Configure LAPB parameter N2 lapb n2 n2-value

Restore the default value of LAPB parameter N2 no lapb n2

By default, n1 is 12032, and n2 is 10.

IV. Configuring LAPB T1, T2, T3

LAPB T1, the retransmission timer (T1) determines how long a sent frame can remainunacknowledged before retransmission. The timer setting must be large enough topermit a maximum-sized frame to complete one round trip on the link.

LAPB T2, the receiving timer (T1) determines when to send a confirmation frame to theopposite DCE (or DTE) before T1 runs out (T2<T1).

LAPB T3, the idle channel timer, determines when to report the long-time idle channelstate to the packet layer. The timer setting must be larger than T1 in DCE (T3>T1). If T3is 0, it indicates that the timer is not in function.

Table LLC-4-5 Configure LAPB system timer T1, T2, T3

Operation Command

Configure LAPB system timer T1 lapb t1 t1-value

Restore the default value of LAPB system timer T1 no lapb t1

Configure LAPB system timer T2 lapb t2 t2-value

Restore the default value of LAPB system timer T2 no lapb t2Configure LAPB system timer T3 lapb t3

t3-value

Restore the default value of LAPB system timer T3 no lapb t3

By default, T1 is 2000ms; T2 is 1000ms and T3 is 0ms.

4.3 Configuring X.25

4.3.1 X.25 Configuration Task List

To transmit data between two routers, you only need to perform simple serial interface

encapsulation using LAPB. If the router is to transmit the data through X.25 publicnetwork, X.25 protocol must be used to encapsulate the serial interface, and X.25protocol should be configured according to the parameters provided by the networkservice provider. Here, we will introduce each of X.25 configuration tasks in detail.





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I. Configuring X.25 interface

l Configure X.25 working model Configure virtual circuit rangel

Configure packet numbering modulol Configure X.121 addressl Configure default flow control parameter (including the setting of window size and

packet length)

II. Configuring X.25 interface supplementary parameter

1) Configure the time delay of X.25 layer 3 timer 2) Configure the attributes related to X.25 address, including the following

configuration items:l Configure the alias of interface addressl Configure to skip the calling or called addressl Configure whether to check the address code block in call accepting packet.l Configure whether to carry the address code block in call accept packet

l Configure default upper layer protocoll Prohibit the restart of X.25 layer 3

III. Configuring X.25 datagram transmission

1) Create the mapping from the protocol address to X.121 address, including thefollowing configuration items:

l About the encapsulation of protocol datagraml About the protocol identifier l Create the address mapping2) Create the permanent virtual circuit

IV. Configuring the supplementary parameters of X.25 datagram transmission

1) Specify the maximum idle time of SVC2) Specify the maximum number of SVCs that is associated with the same address

mapping3) Specify the pre-acknowledgement of packet4) Configure X.25 user facility5) Set the length of virtual circuit queue6) Broadcast via X.257) Restrict the use of address mapping8) Configure the interface with the backup center

Transmit the data with X.25. Choose one task or any task combination according to

specific condition of the employed X.25 public network. Before performing anyconfiguration task, the X.25 protocol parameter corresponding to this task is defaultvalue. Contact the service provider for the parameter values. The X.25 supported byQuidway series router also provides other configuration methods. Besides, appropriatemodification to some LAPB parameters in certain cases can also optimize theperformance of X.25.

4.3.2 Configuring X.25 Interface

Only when configured as an X.25 interface, can an interface transmit data with X.25protocol.





4-7

& Note:

In the following configuration commands, only “Configure X.25 working mode” is obligatory, and other configuration items are optional, depending on the specific condition of X.25 network that is accessed.

I. Configuring X.25 working mode

To configure X.25 working mode, perform the following task in the interfaceconfiguration mode.

Table LLC-4-6 Set X.25 working mode

Operation Command

Set the working mode and encapsulation format of X.25 interfaceencapsulation x25 [ [dte | dce ] | [bf e |cisco-compatible | ddn | ietf ] ]

Layer 3 of X.25 supported by Quidway series router can work in both DTE mode andDCE mode. It can also specify the datagram encapsulation format among the four optional encapsulation formats: BFE, Cisco-compatible, DDN and IETF.

Note that generally speaking, public X.25 packet switching network requires the router to access at DTE side and requires the IETF encapsulation format. Therefore, theworking mode of X.25 should be DTE and the encapsulation format should be IETF. If apair of serial interfaces of two routers is directly connected for data transmission, makesure the two transmission ends are DTE and DCE and the encapsulation formats arethe same.

For X.25 supported by Quidway series router, default working mode is DTE and defaultencapsulation format is IETF.

II. Configuring X.25 virtual circuit range

X.25 protocol can multiplex multiple virtual connection over a real physical link between

DTE and DCE, also called virtual circuit (VC) or logic channel (LC). X.25 can establishup to 4095 virtual connections numbered from 1 to 4095. The number that can beemployed to identify each virtual circuit (or logic channel) is called logic channelidentifier (LCI) or virtual circuit number (VCN).

& Note:Strictly speaking, virtual circuit and logic channel are two different concepts. However, they are notdifferentiated so strictly at the user side.

An important part of X.25 operation is the virtual circuit channel sequence. Thissequence is a range of virtual circuit channel numbers broken into four ranges (listedhere in numerically increasing order):

l Permanent virtual circuits (PVCs)l Incoming-only circuitsl Two-way circuitsl

Outgoing-only circuits





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The incoming-only, two-way, and outgoing-only ranges define the VC numbers over which a switched virtual circuit (SVC) can be established by the placement of an X.25call. The permanent virtual circuits must be set in the PVCs range.

According to ITU-T Recommendation X.25, the rules about DCE and DTE devicesinitiating calls are as follows:

l Only the DCE device can initiate a call in the incoming-only range.l Only the DTE device can initiate a call in the outgoing-only range.l Both the DCE device and the DTE device can initiate a call in the two-way range.l DCE always uses the lowest available logic channel.l DTE always uses the highest available logic channel.

Thus, we can avoid the case that one side of the communication occupies all thechannels, and minimize the possibility of call collision.

In X.25 protocol, six parameters are employed to delimit the four sections, as shown inthe diagram below.

1

LTC

LIC

HTC

HIC

LOC

HOC

4095

Permanent virtual circuit

Incoming-only channel

Unused

Two-wa channel

Unused

Outgoing-only channel

Unused

Figure LLC-4-5 X.25 channel delimitation

For the meanings of these six parameters, please refer to Table 4-4.

Table LLC-4-7 X.25 channel delimitation parameters

Parameter Meaning

LIC Lowest Incoming-only ChannelHIC Highest Incoming-only Channel

LTC Lowest Two-way Channel

HTC Highest Two-way Channel

LOC Lowest Outgoing-only Channel

HOC Highest Outgoing-only Channel

Perform the following task in the interface configuration mode:





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Table LLC-4-8 Set/cancel X.25 virtual circuit range

Operation Command

Set the lowest incoming-only channel number Default value: 0 x25 lic circuit-number

Cancel the set lowest incoming-only channel number no x25 lic

Set the highest incoming-only channel number Default value: 0

x25 hic circuit-number

Cancel the set highest incoming-only channel number no x25 hic

Set the lowest two-way channel number Default value: 1

x25 ltc circuit-number

Cancel the set lowest two-way channel number no x25 ltc

Set the highest two-way channel number Default value: 1024

x25 htc circuit-number

Cancel the set highest two-way channel number no x25 htc

Set the lowest outgoing-only channel number Default value: 0

x25 loc circuit-number

Cancel the set lowest outgoing-only channel number no x25 locSet the highest outgoing-only channel number Default value: 0

x25 hoc circuit-number

Cancel the set highest outgoing-only channel number no x25 hoc

The above shows that each section (except the permanent virtual circuit section) isdefined by two parameters: upper limit and lower limit, the value of which rangesbetween 1 and 4095 (including 1 and 4095). Correct configuration must satisfy thefollowing conditions:

l In strict numerically increasing order, i.e. 1lic hic<ltc htc<loc hoc 4095.l If the upper limit (or lower limit) of a section is 0, then the lower limit (or upper limit)

shall also be 0, (which indicates this section is prohibited to use).

Finally, the following should be noted:

l At the two sides (i.e. DTE and DCE) of a physical connection, the six parametersof X.25 must be equal correspondingly, otherwise, the procedure will possibly tooperate abnormally, resulting in data transmission failure.

l During the configuration, after ensuring the numerically increasing order, payattention to the default values of various parameters, and set the parametersaccording to actual condition.

l Because X.25 protocol requires DTE and DCE to have the same virtual circuitrange parameters, the new configuration can not take effect immediately after successful X.25 protocol negotiation. It is necessary to first execute shutdownand no shutdown commands.

III. Configure X.25 packet sequence numbering modulo

The implementation of X.25 in Quidway series router supports both modulo 8 andmodulo 128 packet sequence numbering. Module 8 is the default.

To set/cancel the packet sequence numbering, perform the following task in theinterface configuration mode:

Table LLC-4-9 Set/Cancel X.25 packet numbering modulo

Operation Command

Set the packet sequence numbering mode x25 modulo { 8 | 128 }

Cancel the set packet sequence numbering mode no x25 modulo





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& Note:

Please note that X.25 procedure requires DTE and DCE to have the same packet numbering mode,therefore the configuration will take effect by executing the shutdown and no shutdown commands.

Besides, the packet sequence numbering mode of X.25 layer 3 is different from the frame sequencenumbering mode of LAPB (X.25 layer 2). When modulo 128 numbering mode is employed in the DTE/DCEinterface with high throughput rate, for LAPB, only the efficiency of local DTE/DCE interface is affected,that is point-to-point efficiency increases. While for X.25 layer 3, the efficiency of end-to-end is affected,that is, the efficiency between two sets of communicating DTE increases.

IV. Configuring X.121 address

If the Quidway series router does not originate or terminate calls but only participates inX.25 switching, this task is optional. However, if the Quidway series router is attachedto a PDN, you must set the interface X.121 address assigned by the X.25 network

service provider. Interfaces that use the DDN or BFE mode will have an X.121 addressgenerated from the interface IP address; for correct DDN or BFE operation, any suchX.121 address must not be modified! You only need to specify an X.121 address for theX.25 interface encapsulated in IETF format.

To set/cancel the X.121 address, perform the following task in interface configurationmode.

Table LLC-4-10 Set/Cancel the X.121 address of the interface

Operation Command

Set the X.121 address of the interface x25 address x.121-address

Cancel the set X.121 address of the interface no x25 address

V. Configuring the default flow control parameter

Setting correct default flow control parameters (window size and packet size) isessential for correct operation of the link because X.25 is a strongly flow controlledprotocol. Mismatched default flow control values will cause X.25 local procedure errors,evidenced by CLEAR and RESET events. However, most public X.25 packet networksuse the default window size and maximum packet size specified in ITU-T X.25Recommendation, which is also true for Quidway series router. Therefore, this taskmay be optional without special requirements of service provider.

After setting default window size and default maximum packet size, the SVCs that can

be established only with call process will use these default values if related parametersare not negotiated in the call process. The PVCs that can be established without callprocess will also use these default values if no window size or packet size option isassigned when specifying PVC.

X.25 transmitting end will fragment the too long data message of upper layer according

to the maximum packet size and mark in the last fragment packet (M bit is not set).When the message reaches the receiving end, X.25 regroups all these fragmentpackets, and judges whether a complete message is received according to M bitmarker. Therefore, too small value of the maximum packet size will consume too muchrouter resources on message fragmenting and repacket, thus lowering efficiency.

Finally, the following two points should be noted:

l Maximum packet size < MTU*8 < LAPB N1.





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l New configuration will take effect only after executing shutdown and no shutdowncommands

To set/cancel the default flow control parameter, perform the following tasks.

Table LLC-4-11 Set the default flow control parameter

Operation Command

Set the default receiving window size of virtual circuitDefault value: 2

x25 win packets

Cancel the set default receiving window size of virtual circuit no x25 win

Set the default sending window size of virtual circuitDefault value: 2

x25 wout packets

Cancel the set default sending window size of virtual circuit no x25 wo ut

Set the default receiving maximum packet lengthDefault value: 128

x25 ips bytes

Cancel the set default receiving maximum packet length no x25 i ps

Set the default sending maximum packet length

Default value: 128

x25 ops bytes

Cancel the set default sending maximum packet length no x25 op s

4.3.3 Configuring X.25 Interface Supplementary Parameter

It's necessary to configure certain supplementary X.25 parameters in some specialnetwork environments.

I. Configuring the delay of X.25 layer 3 timer

X.25 protocol defines a series of timers to facilitate its procedure. After X.25 sends a

control message, if it does not receive the response before the timeout of thecorresponding timer, X.25 protocol will take corresponding measure to handle thisabnormal event. The names and corresponding procedures of these timers are shownin the following table.

Table LLC-4-12 X.25 layer 3 timer

Timer nameProcedure name

DTE side DCE side

Restart T20 T10Call T21 T11

Restore T22 T12

Clear T23 T13Register T28

In the table, T28 is the timer of “ sending register request” , and is only defined at the

DTE side. It is used to dynamically apply for or stop the selective services in thenetwork. Its reference value is 300 seconds, and cannot be modified. Perform thefollowing tasks in the interface configuration mode.





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Table LLC-4-13 Set X.25 layer 3 timer delay

Operation Command

Set the timer delay value of restart procedureDefault value (second):DTE 180 DCE 60 x25 tx0 seconds

Cancel the set timer delay value of restart procedure no x25 tx0

Set the timer delay value of call procedureDefault value (second):DTE: 200 DCE: 180

x25 tx1 seconds

Cancel the set timer delay value of call procedure no x25 tx1

Set the timer delay value of restore procedureDefault value (second):DTE: 180 DCE: 60

x25 tx2 seconds

Cancel the set timer delay value of restore procedure no x25 tx2

Set the timer delay value of clearing procedureDefault value (second):DTE: 180 DCE: 60

x25 tx3 seconds

Cancel the set timer delay value of clearing procedure no x25 tx3

II. Configuring the attribute related to X.25 address

To establish a SVC with a call, X.25 address is needed, which adopts the addressformat specified in ITU-T Recommendation X.121. X.121 address consists of a string of Arabic numerals from 0 to 15.

1) Configure an alias for the interface

When an X.25 call is forwarded across the network, different networks will likely tomake some modifications on the called address according to their own needs, such asadding or deleting the prefix. In such cases, the destination address of a call thatreaches X.25 interface may be inconsistent with X.121 address of the destinationinterface (because the destination address of this call is modified within the network),still the interface will accept this call. At this time, one or multiple aliases should be

specified for this interface by performing the following tasks in the interfaceconfiguration mode:

Table LLC-4-14 Specify/Cancel an alias for the interface

Task Command

Specify an alias for the interface x25 alias match-type alias-string

Cancel the specification of an alias for the interface no x25 alias match-type alias-string

To satisfy the requirements of different networks, nine matching modes and the formatsof corresponding alias strings are defined for X.25 in Quidway series router, as shownin the following table.

Table LLC-4-15 Alias match modes and meanings

Matching mode Meaning Example

FreeFree matching, the alias string is in theform of 1234

1234 will match with 561234, 1234567 and956123478, but will not match with 12354.

free-extExtended free matching, the alias stringis in the form of …0.1234..

…1234.. will match with 678123459, but willnot match with 68123459, 67812345 and6781234591.

LeftLeft-justified matching mode, the aliasstring is in the form of $1234

$1234 will match with 1234567 and 12346790,but will not match with 3123478 and 123784.

left-extExtended left-justified matching mode,the alias string is in the form of $1234…

$1234…will match with 1234679 and1234872, but will not match with 123468 and

12346890.





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Matching mode Meaning Example

RightRight-justified match mode, the aliasstring is in the form of 1234$

1234$ will match with 791234 and 6901234,but will not match with 7912345 and 6212534.

right-ext Extended right-justified matching mode,the alias string is in the form of ….1234$

….1234$ will match with 79001234 and

86901234, but will not match with 7912345 and506212534.

StrictStrict matching mode, the alias string isin the form of $1234$

$1234$ can only match with 1234

WholeWhole matching mode, the alias string isin the form of ........

........ will match with all the valid X.121addresses with the length of 8

whole-extExtended whole matching mode, thealias string can only be *

* will match with all the valid X.121 addresses

2) Configure the attributes related to the address code block in the call packet or callaccept packet

As specified in X.25 protocol, the call packet must carry the information set of both the

calling DTE address (source address) and the called DTE address (destinationaddress). This address information set is called the address code block. While in callaccept packet, some networks require that both (the calling DTE address and thecalled DTE address) be carried, some networks require that only one of the two becarried, while some others require that neither should be carried. X.25 in Quidwayseries router enables users to make choices according to the requirement of specificnetwork. Perform the following task in interface configuration mode.





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Table LLC-4-16 Configure/Cancel the attributes related to the address code block in the call packet or callaccept packet

Operation Command

Not carrying the called DTE address information when a call is originatedDefault: carry

x25 suppress-called-address (bydefault)

Cancel not carrying the called DTE address information when a call isoriginated

no x25 suppress-called-address

Not carrying the calling DTE address information when a call is originatedDefault: carry

x25 suppress-calling-address (bydefault)

Cancel not carrying of the calling DTE address information in a call no x25 suppress-calling-address

Not carrying the called DTE address information when the originated call isacceptedDefault: not carry

x25 respons e-called-address

Cancel not carrying of the called DTE address information when theoriginated call is accepted

no x25 response-called-address

(by default)Not carrying the calling DTE address information when the originated call is

acceptedDefault: not carry x25 response-calling-address

Cancel not carrying the calling DTE address information when theoriginated call is accepted

no x25 response-calling-address

(by default)Check the address code block after the response of the call is receivedDefault: not check

x25 check-response-address

Cancel check the address code block after the response of the call isreceived

no x25 check-response-address(by default)

By default, the upper protocol carried by X.25 is IP protocol.

3) Configure default upper layer protocol

In the X.25 call request packet, there is a field called Call User Data (CUD). The first

few bytes of this domain differentiate the message type of upper layer protocol this callis bearing. When the router is the destination host, it will refuse to receive a call withunrecognizable CUD. But an upper layer protocol can be specified as the defaultprotocol borne on the X.25 of the Quidway series router. When the X.25 of the Quidwayseries router receives a call with an unrecognizable CUD, it will treat it as the defaultupper layer protocol specified by user.

In the interface configuration mode, perform the following task to set/cancel the defaultupper layer protocol borne on X.25.

Table LLC-4-17 Set/Cancel the default upper layer protocol borne on X.25

Operation Command

Specify the default upper layer protocol borne on X.25Default: IPx25 default [ ip | ipx ]

Cancel the specifying of the default upper layer protocolborne on X.25

no x25 default [ i p | ipx ]

4) Prohibit the restart of X.25 layer 3

Generally, when the X.25 layer 2 (LAPB) is restarted, the X.25 layer 3 will also berestarted. This is essential for the correct running of the protocol procedure. However,user can also disable this function so that the X.25 layer 3 does not restart even after the X.25 layer 2 is restarted. In the interface configuration mode, perform the followingtask to prohibit the restart of X.25 layer 3.





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Table LLC-4-18 Permit/Prohibit the restart of X.25 layer 3

Operation Command

Enable the restart of X.25 layer 3 x25 linkrestart

Disable the restart of X.25 layer 3 no x25 linkrestart

By default, enable the restart of X.25 layer 3.

& Note:

Do not run this command unless absolutely necessary. It is recommended to enable the restart of X.25layer 3.

4.3.4 Configuring X.25 Datagram Transmission

In the most frequently used X.25 service, data is transmitted remotely between twohosts using the X.25 protocol via X.25 public packet network. As shown in the figurebelow, LAN A and LAN B are far apart, and X.25 packet switching network can be usedto realize information exchange between them.

X.25LAN A

LAN B

Router A

Router B

Figure LLC-4-6 LAN interconnection via X.25

The datagram uses IP address to communicate data and information between LAN A

and LAN B, whereas X.121 address is used inside X.25. Therefore, we setup correctmapping between the IP address and X.121 address.

I. Creating the mapping from the protocol address to X.121 address

An X.25 interface has its own X.121 address and inter-network protocol (such as IP

protocol) address. When X.25 initiates a call through this interface, the source address(calling DTE address) it carries in the call request packet is the X.121 address of thisinterface.

For a datagram with a definite destination IP address, its corresponding X.121

destination address is located by the configured address mapping. The call destination, just like a calling source, also has its own protocol address and X.121 address.Establish the mapping between the destination protocol address and the X.121address at the calling source, you can find the destination X.121 address according tothe destination protocol address, and successfully initiate a call.

In the interface configuration mode, perform the following commands to create/deletean address mapping.





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Table LLC-4-19 Create/Delete the mapping from the protocol address to X.121 address

Operation Command

Create the mapping from the destination protocoladdress to X.121 address

x25 map protocol protocol-address x.121-address

[ option ]

Delete the mapping from the destination protocoladdress to X.121 address

no x25 map protocol protocol-address

& Note:

The protocol-address and x.121-address in the command line refer to the protocol address and X.121address of the destination, not those of the source.

An address mapping should be created for every destination.While creating an address mapping, specify its attributes with the option items. The meanings and specificcontent of these options will be described in subsequent sections.

For the address mapping configuration example, refer to subsequent sections.

II. Creating the permanent virtual circuit (PVC)

A permanent virtual circuit can be created for large-traffic and stable data transmissionon leased line. Permanent virtual circuits (PVCs) do not need any call process and italways exists. An address mapping will be created implicitly while a permanent virtualcircuit is created.

To create/delete a permanent virtual circuit, perform the following tasks in interfaceconfiguration mode.

Table LLC-4-20 Create/Delete permanent virtual circuit

Operation Command

Create a permanent virtual circuitx25 pvc pvc-number protocol protocol-address x.121-address[ option ]

Delete a permanent virtual circuit no x25 pvc pvc-number

The format of this command shows that while a permanent virtual circuit is created, anaddress mapping is also created for it. Similarly, the protocol-address and x.121-

address in the command also refer to the destination address. While creating apermanent virtual circuit, some attributes of the PVC can also be selected via the option.This [option] is a subset of [option] in the command "x25 map...... [option]".

For configuration example of permanent virtual circuit, refer to subsequent sections.

4.3.5 Configuring Additional Parameters of X.25 Datagram Transmission

The X.25 of Quidway series router allows adding some additional characteristics,including a series of optional user facilities stipulated in ITU-T Recommendation X.25.

This section shows how to configure such additional characteristics, including theoptions in the two commands of "x25 map ......" and " x25 pvc......". Please select andconfigure these additional characteristics according to the actual needs, X.25 network

structure and the services provided by service provider.





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I. Configuring SVC maximum idle time

Specify a time period, and if SVC is idle within this period (no packet interaction), thenX.25 of the Quidway series router will automatically clear this SVC to avoid

unnecessary expenses. Before the data packet is sent next time, this SVC will bereestablished. So the activation of this characteristic will not affect data transmission.

In the interface configuration mode, this task can be accomplished in two different ways.For details, refer to the table as follows.

Table LLC-4-21 Specify/Cancel SVC maximum idle time

Operation Command

Specify maximum idle time for all the SVCs on an interface x25 idle minutes

Specify maximum idle time for SVC associated with anaddress mapping

x25 map protocol protocol-address x.121-address idle minutes

Cancel specify maximum idle time for all the SVCs on aninterface

no x25 idle

II. Configuring the maximum number of SVCs that are associated with thesame address mapping

The maximum number of virtual circuits to be set up on the same address mapping can

be specified. The X.25 of Quidway series router can establish up to 8 virtual circuits onone address mapping. In case of large traffic and low line rate, this parameter can beincreased properly to reduce data loss. By default, one address mapping is associatedwith only one virtual circuit.

In the interface configuration mode, perform the following commands.

Table LLC-4-22 Specify/Cancel the maximum number of SVCs associated with the same addressmapping

Operation Command

Specify the maximum number of SVCs associated with all addressmappings on an X.25 interface

x25 nvc count

Specify the maximum number of SVCs associated with an addressmapping

x25 map protocol protocol-address

x.121-address nvc count

Cancel the maximum number of SVCs associated with all addressmappings on an X.25 interface

no x25 nvc

III. Configuring the pre-acknowledgment of packets

According to X.25 protocol, the receiving party will send an acknowledgment only after the receiving window is full (the number of received packets equals the win value).However, in some X.25 networks, the delays may be long, resulting in low efficiency of sending and receiving. Therefore, we specify a value. Each time the number of received packets reach the value, the acknowledgment will be sent to the peer, thusimproving receiving and sending efficiency. This value, called a "threshold", rangesbetween 0 and win . If it is set to 1, every packet will be acknowledged. If it is set to win ,the acknowledgment will be sent only after the receiving window is full. In applicationsrequiring a high response speed, this function is especially important.

In the interface configuration mode, perform the following task.





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Table LLC-4-23 Specify/Cancel packet pre-acknowledgement

Operation Command

Set packet acknowledgment value x25 threshold packet-count

Cancel packet acknowledgment value no x25 threshold

IV. Configuring X.25 user facility

The X.25 in the Quidway series router supports the user facility options defined inITU-T Recommendation X.25, such as reverse charging negotiation and flow controlparameter negotiation. These configurations can be modified in two ways:

Configuration based on X.25 interface (use "x25 facility....." command); configurationbased on address mapping (use "x25 map......" command).

The configuration based on X.25 interface will be effective in every call originated fromthis X.25 interface, while the configuration based on address mapping will be effectiveonly in the calls originated from this address mapping.

In the interface configuration mode, perform the following task.





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Table LLC-4-24 Configure X.25 user facility

Operation Command

Specify CUG (Closed User Group)

x25 facility cug group-number

Or x25 map protocol protocol-address x.121-address cuggroup_number

Cancel CUG number no x25 facility c ug

Perform flow control parameter negotiation whileinitiating a call

x25 facility packetsize in-size out-size 1

Or x25 map protocol protocol-address x.121-addresspacketsize in-size out-size 1

x25 facility w indowsize in-size out-size 1

Or x25 map protocol protocol-address x.121-address

windowsize in-size out-size 1

Cancel flow control parameter negotiation whileinitiating a call

no x25 facility packetsizeOr no x25 facility windo wsize

Request reverse charging while initiating a callx25 facili ty reverse

Or x25 map protocol protocol-address x.121-address reverse

Cancel the request of reverse charging whileinitiating a call

no x25 facility reverse

Receive calls with reverse charging requests

x25 accept-reverse

Or x25 map protocol protocol-address x.121-address accept-

reverse

Request throughput-level negotiation whileinitiating a call

x25 facility through put in out

Or x25 map protocol protocol-address x.121-address

throughput in outCancel the request of throughput-level negotiationwhile initiating a call

no x25 facility throug hput

Carry transmission delay request while initiating acall

x25 facility transit-delay millisecondsOr x25 map protocol protocol-address x.121-address transit-

delay milliseconds

Cancel the carrying of transmission delay requestwhile initiating a call

no x25 facility transit-delay

Specify the use of ROA (Recognized operating Agency)

x25 facility roa name 2

Or x25 map protocol protocol-address x.121-address roa name 2

Cancel the use of ROA no x25 facility roa

Here:

windowsize and packetsize options are also supported in x25 pvc command.However, in x25 pvc command, these two options specify the window size andmaximum packet length of the set PVC. If these two options are not selected in the x25pvc command, the set PVC will choose the default value of X.25 interface.

name is the name of the ROA ID list configured by the command x25 roa in the globalconfiguration mode, for example:

Quidway(config)# x25 roa list1 12 34 567

In the serial port configuration mode, list1 can be quoted:





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Quidway(config-if-Serial0)# x25 facility roa list1

V. Configuring the sending queue length of virtual circuit

The sending and receiving queue lengths of the virtual circuit can be specified for theX.25 of the Quidway series router to adapt to different network environments. Thedefault queue length can contain 500 packets, but if data flow is very large, or thetransmission rate of the X.25 network is low, the queue length can be increased toavoid unexpected data packet loss.

In the interface configuration mode, perform the following tasks to specify the length of virtual circuit queue.

Table LLC-4-25 Configure the sending queue length of virtual circuit

Operation Command

Set the length of X.25 virtual circuit queue x25 hold -queue queue-size

Cancel set the length of X.25 virtual circuit queue no x25 hold-queue

VI. Broadcasting via X.25

Generally, inter-network protocols will need to send some broadcast datagrams for specific purposes. On the broadcasting physical networks (such as Ethernet), suchrequirements are naturally supported. But for non-broadcasting networks like X.25,how to realize the broadcasting?

The X.25 of the Quidway series router enables decision of whether to duplicate andsend a broadcasting data packet to a destination. This is very important. For instance,the broadcast-based application layer routing protocol will request broadcasting

datagram sent by X.25 to exchange routing information on the X.25 network.

It can be specified whether to send broadcasting data packets on the related virtualcircuits of both SVC and PVC.

Table LLC-4-26 Set broadcasting via X.25

Operation Command

Enable to send broadcasting data packets to the peer of theSVC associated with this address mapping

x25 map protocol protocol-addressx.121-address broadcast

Enable to send broadcasting data packets to the peer of thisPVC

x25 pvc pvc-number protocol protocol-address

x.121-address broadcast

VII. Restricting the use of address mapping

X.25 calls are closely related to address mapping: before a destination is called, this

destination must be found in the address mapping table. Before a call is received, thesource of this call must also be found in the address mapping table. But in some cases,some address mappings are used for calling out only, while others are used for callingin only.

The X.25 of the Quidway series router allows restricting the use of this addressmapping addition by adding some option items, as shown in the following table.





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Table LLC-4-27 Restrict the use of address mapping

Operation Command

Inhibit outgoing call through this address mappingx25 map protocol protocol-address

X.121-address no-outgoing

Inhibit incoming call through this address mappingx25 map protocol protocol-addressX.121-address no-incoming

VIII. Configuring interface with backup center

The powerful backup function of Quidway series router is provided by the "backup

center". To add an X.25 interface into the backup center, perform the following task inthe interface configuration mode (for details of the "backup center", refer to the chapter about “Backup Center” ).

Table LLC-4-28 Set interface with backup center

Operation Command

Set the logic interface number of this address mapping in thebackup center

X25 map protocol protocol-address x.121-

address lin logical-interface-number

4.3.6 Configuring X.25 Sub-Interface

X.25 sub-interface is a virtual interface with its own protocol address and virtual circuit.Multiple sub-interfaces can be created on a physical interface, so the networks can beinterconnected via one physical interface. The sub-interface of X.25 falls into two types:

point-to-point sub-interface, used to connect a single remote end and point-to-multipoint sub-interface, used to connect multiple remote ends in the same networksegment.

In the interface configuration mode, perform the following task to configure X.25 sub-interface.

Table LLC-4-29 Configure X.25 sub-Interface

Operation Command

Create X.25 sub-interfaceinterface serial number.subinterface-number {multipoint|point-to-point}

Configure address mapping

Or Configure permanent virtual circuit

x25 map protocol protocol-address x.121-address [option]

or x25 pvc pvc-number protocol protocol-address

x.121-address [option]

4.3.7 Configuring X.25 Switching

I. X.25 switching function

A packet network consists of many nodes interconnected in a certain topological

structure. From the source to its destination, a packet will pass through many nodes,each of which must have packet switching capability.





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To put it simply, X.25 packet switching means to receive packets from one X.25 port,and send them out from the X.25 port selected according to related destination addressinformation contained in the packets. X.25 switching enables the Quidway series router to perform packet switching function in the packet layer, and to be used as a small

packet switching exchange.

Quidway series router provides such X.25 switching functions as follows:

l SVC switching functionl Support parameter negotiation on window size and packet sizel PVC switching

The following describes how to configure X.25 switching tables for PVC and SVC.

PCPC

Quidway Router

X.25 host X.25 host

Figure LLC-4-7 X.25 switching networking diagram

II. Enabling or disabling X.25 switching

In the global configuration mode, perform the following task to enable or disable X.25switching.

Table LLC-4-30 Enable or disable X.25 switching

Operation Command

Enable X.25 switching x25 routing

Disable X.25 switching no x25 routing

III. Adding or deleting a PVC route

Table LLC-4-31 Add or delete a PVC route

Operation Command

Add a PVC route x25 pvc number interface serial port-number pvc number

Delete a PVC route no x25 pvc number interface serial port-number pvc number

Example: Set to encapsulate X.25 on a router's serial port 0 and serial port 1, add PVCvirtual circuit route into the virtual circuit route table, so that packets can be switchedbetween the 1st PVC of serial port 0 and the 1st PVC of serial port 1.

Quidway(config)# x25 routing






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Quidway(config-if-Serial0)# encapsulation x25 dce

Quidway(config-if-Serial0)# x25 lic 10

Quidway(config-if-Serial0)# x25 hic 20

Quidway(config-if-Serial0)# x25 ltc 30

Quidway(config-if-Serial0)# exit






Quidway(config-if-Serial1)# x25 pvc 1 interface serial 0 pvc 1

In the configuration of PVC switching, the two connected ports must be encapsulatedinto X.25, and there should be valid Permanent virtual circuits (PVCs). After configuration, the show x25 vc command can be used to show the virtual circuit routetable. For this command, refer to the section about X.25 configuration.

IV. Adding/Deleting an SVC route

In the global configuration mode, the commands in the following table can be used toadd or delete an SVC route.

Table LLC-4-32 Add or delete an SVC route

Operation Command

Add an SVC route x25 route

x.121-addr interface serial interface-number

Delete an SVC route no x25 route x.121-addr interface serial interface -number

Example: Set to encapsulate serial port 0 and serial port 1 as X.25, add into the X.25switching route table SVC switching routes: 1S0, 2 S1.

Then the two hosts connected to this router can directly communicate with each other on X.25 by calling 1 and 2.


Quidway(config-if-Serial0)# encapsulation x25 dce ietf



Quidway(config-if-Serial1)# encapsulation x25 dce ietf

Quidway(config)# x25 route 1 interface serial 0






4-24

& Note:

The window size and packet size of the two hosts switched via the Quidway series router can be different.The smaller value of the two can be negotiated via the switching module.

In the configuration of SVC switching, the two connected ports do not have to beencapsulated as X.25, but during communication they must be encapsulated. After theconfiguration, use show x25 route command to show the switching route table.

4.3.8 Configuring XOT

I. Introduction to XOT Protocol

XOT (X.25 Over TCP) is a protocol that is supported by TCP, and implements the

connection of two X.25 networks through IP network. The practical applicationenvironment is shown in the following figure.

X.25 IP X.25

Quidway A Quidway B Quidway C Quidway D

Figure LLC-4-8 XOT typical application diagram

Since the application of IP network is broader and broader, the practical applications of

supporting X.25 data through IP net and connecting X.25 networks are becoming moreand more. The conventional X.25 protocol is the third layer of the OSI seven-layer

model, i.e., the network layer, for which the LAPB protocol provides reliable datatransmission link. Because TCP has the mechanism of error redirection and windowflow controlling to guarantee the reliability of links, it can be applied by X.25. XOT buildsa TCP tunnel connection between the two X.25 networks, and the X.25 packets aresupported by TCP as data of application layer, i.e., TCP serves as the “ link layer” of X.25. You can regard the middle QuidwayB, QuidwayC and IP net as a big “ X.25switch”, and data is directly switched from QuidwayA to QuidwayD through this“switch”.

The XOT features implemented in VRP accords with RFC1613 recommendation, and itpossess the following features:

l Supporting SVC application. The two routers can dynamically set up a SVC bysending call packet, and the VC will automatically be cleared when no data is

transmitted.l Supporting PVC application. After the two routers configure a PVC, they directly

enter the data transmission status without the process of call establishing. If nodata is transmitted, this VC will not be cleared dynamically.

l Supporting the Keepalive attribute of TCP. If Keepalive is not configured, TCPconnection will not be cleared or be cleared after a long period of time when theline is disconnected. If Keepalive is configured, TCP check the usability of the linksin time, and it will automatically clear the TCP connection if it does not receive theanswer of the opposite side for many times.

Implementing theory of XOT (taking SVC as an example):

As shown in the former figure, when it has data to transmit, QuidwayA first send arequest packet to set up a VC. After QuidwayB receive the call packet and know that it

is XOT application through judging, it first set up a TCP connection with QuidwayC, and





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then stick the XOT packet header to X.25 call packet packet which is encapsulated inTCP to send to QuidwayC. QuidwayC takes off the TCP and XOT packet headers andsend the call request packet to QuidwayD through X.25 local switch. After QuidwayDreceives the call request packet, it answers the call to confirm until the link is completely

set up and enters the data transmission status. To QuidwayA and QuidwayD, the wholeprocess of setting up and applying TCP connection is transparent, and they do not andcannot care whether the data is forwarded through IP net or X.25 net.

II. Configuring XOT

1) XOT configuration task list

XOT configuration task list is as follows:

l Start X.25 switchingl Configure IP side interfacel Configure local switching (SVC)l Configure XOT routel Configure Keepalive and xot-source attributes (optional)2) Start X.25 switching

Because the XOT is the extension of X.25 switch, first you have to start X.25 switch.

Perform the following tasks in global configuration mode.

Table LLC-4-33 Start X.25 switching

Operation Command

Start X.25 switching x25 routing

By default, do not start X.25 switch.

3) Configure IP side interfaceBecause the XOT implements the connection of two X.25 nets through IP net, first you

should ensure that the IP net is expedite. For the specific configuration, refer tochapters of “ Network protocol configuration” in this manual.

4) Configure local switching (SVC)

For SVC, when it receives the packets from the remote side, it must send out thepackets through local switch interface, so you have to configure local switching.

The following commands determine: In SVC, through which switch interface thepackets getting to local side will be sent out.

Perform the following tasks in global configuration mode.

Table LLC-4-34 Configure local switching

Operation Command

Configure X.25 local switching x25 route X.121-address interface serial interface-number

Delete X.25 local switching no x25 route X.121-address interface serial interface-number

5) Configure XOT route

The following configuration determines how the X.25 side packets received areforwarded through IP net. There are different configuration modes for SVC and PVC.

For SVC, perform the following tasks in global configuration mode.





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Table LLC-4-35 Configure SVC XOT switching

Operation Command

Add a SVC XOT route x25 route dest-address xot ip-address

Delete a SVC XOT route no x25 route dest-address xot ip-address

& Note

The local X.25 route must be configured in the SVC mode.

For PVC, perform the following tasks in interface configuration mode.

Table LLC-4-36 Configure PVC XOT switching

Operation Command

Add a PVC XOT route x25 pvc vc number xot ip address interface type number

Delete a PVC XOT route no x25 pv c vc number

6) Configure Keepalive and xot-source attributes (optional)

After the TCP link is established, TCP will not be easily cleared even if the link isdisconnected. But after configuring Keepalive, the router will send checking packets intime to check the usability of the link. If it cannot get confirmation after sending outpackets several times, it will consider the link failure and clear it automatically.

Table LLC-4-37 Configure Keepalive and xot-source attributes

Operation Command

Configure SVC Keepalive and xot-source attributes

x25 route x.121 address xot ip address xot-keepalive-period period

xot-keepalive-tries times xot-source interface type number

Configure PVC Keepalive and xot-source attributes

x25 pvc vc number xot ip address interface serial number xot-

keepalive-period period xot-keepalive-tries timesxot-source interfacetype number

III. Monitoring and Maintenance of XOT

In privileged user mode, the system provides XOT debugging commands to show theestablishment of TCP and the status of X25 VC.

Table LLC-4-38 Monitoring and Maintenance of XOT

Operation Command

Show the establishment of TCP show tcp brief

Show the status of X25 VC show x25 vc

Enable X25 information debugging(transceiving packets, timer, event,limited state machine)

debug x25 xot

1) Check X.25 VC table

The command show x25 vc is used to show all the virtual circuits in effect on all the

X.25 interfaces.





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Quidway# show x25 vc

SVC 1024, State: TRANSFER, Interface: Serial11/0/2Started: 2001-9-30 13:48:29, Last input: 0:0:18, Last output: 0:0:18

Connects: X.121 <--> ietf10.1.1.2 vc 1024 cud pid, no Tx data PIDWindow size: input 2 output 2Packet Size: input 128 output 128PS: 0 PR: 0 ACK: 0 Remote PR: 0 RCNT: 0RNR: FALSE Reset times: 0input/output: DATA 5/5 INTERRUPT 0/0 Bytes 420/420 RR 0/0 RNR 0/0 REJs 0/0Snd Queue: Current length 0 Max length 500 Drops 0Rcv Queue: Current length 0 Max length 500 Drops 0

SVC 1024, State: TRANSFER, Interface: 10.1.1.2Started: 2001-9-30 13:48:29, Last input: 0:0:18, Last output: 0:0:18

Connects: X.121 <--> ietfSerial11/0/2 vc 1024 cud pid, no Tx data PIDWindow size: input 2 output 2Packet Size: input 128 output 128PS: 0 PR: 0 ACK: 0 Remote PR: 0 RCNT: 0RNR: FALSE Reset times: 0input/output: DATA 5/5 INTERRUPT 0/0 Bytes 420/420 RR 0/0 RNR 0/0 REJs 0/0Snd Queue: Current length 0 Max length 500 Drops 0Rcv Queue: Current length 0 Max length 500 Drops 0

The upper information indicates: On X.25 interface Serial11/0/2, there is a temporaryVC in effect with the serial number 1024.





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Table LLC-4-39 Information about X.25 virtual circuit

Field Meaning

SVC 1The type and number of the virtual circuit. SVC stands for the switched virtual circuit, andPVC for the permanent virtual circuit

State Current state of the virtual circuitInterface Name of the interface on which the virtual circuit is established

Started Time elapsed since the VC was created. Format: : year-month-day hour: minute: second

Last inputTime of last input (when the show x25 vc is executed) on the virtual circuit. Format: hour:minute: second

Last outputShows time of the last output (when the show x25 vc is executed) on the virtual circuit.Format: hour: minute: second

Connects

If the router is the start / end point (that is, the router does not work in X.25 switchedmode), this field indicates the address map attached to this virtual circuit. If the virtualcircuit is set up for switching (that is, the router works in switched mode), this fielddescribes the type and number of the VC on another X.25 interface attached to this VC.For example, “Serial1 SVC 1024” indicates that this VC is attached to SVC1024 on theX.25 interface Serial1

Window size The incoming window size and outgoing window size of this VCPacket size The maximum packet size of this VC

Vs Variable currently sent on this VCVr Variable current received on this VC

ACK Current acknowledgement variable on this VCRemote Vr Last acknowledgement from the far end on this VCRCNT Count of unacknowledged output packets

RNRIf this VC is in the “Receiver Not Ready” status. TRUE indicate that it is in this status, andFALSE indicates that it is not in this status

Reset times Number of VC reset timesinput/output:DATA...REJ 0/0

Statistics about this VC, including the input and output packets, and the total bytes of allthe data packets

Snd QueueCurrent status of the output queue of this VC: maximum hold size, current queue length,and packets dropped due to a full queue

Rcv QueueCurrent status of the input queue of this VC: maximum hold size, current queue length,and packets dropped due to a full queue

2) In privileged user mode, the command show tcp brief is used to show theestablishment of TCP.

Quidway# show tcp brief LocalAddress LocalPort ForeignAddress ForeignPort State010.001.001.002 1998 010.001.001.001 1034 ESTABLISHED000.000.000.000 23 000.000.000.000 0 LISTEN000.000.000.000 1998 000.000.000.000 0 LISTEN

The upper information indicates: local 10.1.1.2 and the opposite 10.1.1.1 establish TCPconnection. This side uses port 1998 and the opposite side uses port 1034.

4.4 Monitoring and Maintenance of LAPB, X.25 and X.25Switching

In the privileged mode, perform the following tasks to enable real-time monitoring of thecurrent status of LAPB, X.25 and X.25 switching.





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Table LLC-4-40 Maintenance and monitoring of LAPB, X.25 and X.25 switching

Operation Command

Show interface information show interface [ type number ]

Show X.25 alias table show x 25 alias

Show X.25 address mapping table show x 25 mapShow X.25 switching route table show x25 route

Show X.25 switching virtual circuit table show x25 switch-vc-table

Show X.25 virtual circuit show x25 vc lci-number

Enable X.25 information debugging debug x25 all [interface interface-type interface-number ]

Disable X.25 information debugging no debug x25 all [interface interface-type interface-number ]

Enable X.25 event debugging debug x25 event [interface interface-type interface-number ]

Disable X.25 event debugging no debug x25 event [interface interface-type interface-number ]

Enable X.25 packet debugging debug x25 packet [interface interface-type interface-number ]

Disable X.25 packet debugging no debug x25 packet [interface interface-type interface-number ]

4.4.1 Displaying the Information of Interface Encapsulated LAPB

The following tasks can encapsulate interface Serial0 as LAPB protocol, and displayinterface information after encapsulation:

Quidway# configure


Quidway(config-if-Serial0)# encapsulation lapb

Quidway(config-if-Serial0)# show interface serial 0

Serial0 is down, line protocol is downphysical layer is synchronous, baudrate is 64000 bpsinterface is DCE, clock is DCECLK, no cableEncapsulation LAPBLAPB DTE, module 8, k 7, N1 12032, N2 5timer: T1 2000, T2 1000, T3 0 (milliseconds)state DISCONNECT, VS 0, VR 0, Remote VR 0IFRAME 0/0, RR 0/0, RNR 0/0, REJ 0/0FRMR 0/0, SABM 0/0, DM 0/0, UA 0/0DISC 0/0, Invalid Ns 0, Invalid Nr 0, Link Resets 00 packets input, 0 bytes, 0 no buffers0 packets output, 0 bytes, 0 no buffers0 input errors, 0 CRC, 0 frame errors0 overrunners, 0 aborted sequences, 0 input no buffers

After inputting the command serial, the above information will display. The parts in bold

are related to the LAPB protocol, and the meaning of each field is as follows.





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Table LLC-4-41 LAPB information shown byshow interface command

Field Meaning

Encapsulation LAPB Current encapsulation protocol of this interface is LAPB protocol

LAPB DTE LAPB of this interface works in DTE mode

module 8Information frame and monitoring frame sent by this interface LAPB arenumbered in the modulo 8 mode

k 7 Window size of this interface LAPB is 7

N1 12032 The maximum length of frame sent by the interface LAPB is 12032 bits

N2 5 Maximum re-sending times of information frame of this interface LAPB is 5timer: Delay value of timers of this interface LAPB, in unit of millisecond

state Current status of this interface LAPB

VS Sending variable of this interface LAPB

VR Receiving variable of this interface LAPB

Remote VRPeer’ s last acknowledgment on information frame received by this interfaceLAPB

IFRAME 0/0 ... DISC 0/0Statistics information of frames sent and received by this interface LAPB,

format: received quantity/sent quantityInvalid Ns

Error statistics of this interface LAPB: total of received information framescarrying erroneous sequence numbers

Invalid Nr Error statistics of this interface LAPB: total of received information framesand monitoring frames carrying erroneous acknowledgment numbers

Link Resets Restarting times of this interface LAPB link

4.4.2 Displaying the Information of Interface Encapsulated X.25

The following command series encapsulates interface Serial1 with X.25 protocol, andexits to the privileged user mode to show the interface information after encapsulation:

Quidway# configure


Quidway(config-if-Serial1)# encapsulation x25


Quidway(config)# exit

Quidway# show interface serial 1

Serial1 is down, line protocol is downphysical layer is synchronous, baudrate is 9600 bpsinterface is DCE, clock is DCECLK, no cable

Encapsulation X.25 DTE IETF, address is , state Ready, modulo 8input/output: window sizes 2/2, packet sizes 128/128Channels: Incoming-only 0-0, Two-way 1-1024, Outgoing-only 0-0Timers: T20 180, T21 200, T22 180, T23 180, T28 300, Idle_Timer 0

New configuration (will be effective after restart): modulo 8input/output: window sizes 2/2, packet sizes 128/128Channels: Incoming-only 0-0, Two-way 1-1024, Outgoing-only 0-0Statistic: Restarts 0 (Restart Collisions 0)Refused Incoming Call 0, Failing Outgoing Call 0input/output: RESTART 0/0 CALL 0/0 DIAGNOSE 0/0 DATA 0/0 INTERRUPT 0/0 Bytes 0/0 RR 0/0 RNR 0/0 REJ 0/0Invalid Pr: 0 Invalid Ps: 0 Unknown: 0LAPB DTE, module 8, k 7, N1 2104, N2 5timer: T1 2000, T2 1000, T3 0 (milliseconds) state DISCONNECT, VS 0, VR 0, Remote VR 0 IFRAME 0/0, RR 0/0, RNR 0/0, REJ 0/0





4-31

FRMR 0/0, SABM 0/0, DM 0/0, UA 0/0 DISC 0/0, invalid ns 0, invalid nr 0, link resets 05 minutes input rate 0.00 bytes/sec,0.00 packets/sec5 minutes output rate 0.00 bytes/sec,0.00 packets/secInput queue:(size/max/drops)

0/1000/0Queueing strategy:FIFO

Output queue:(size/max/drops

0/1000/00 packets input, 0 bytes, 0 no buffers0 packets output, 0 bytes, 0 no buffers0 input errors, 0 CRC, 0 frame errors0 overrunners, 0 aborted sequences, 0 input no buffersDCD=UP DTR=DOWN DSR=UP RTS=DOWN CTS=UP

After inputting the command serial, the above information will be displayed. The boldparts are related to LAPB and X.25 protocol. LAPB has already been introduced in theprevious section. For meanings of various fields related to X.25 protocol, refer to thefollowing table.

Table LLC-4-42 X.25 information shown by show interface command

Field Meaning

Encapsulation X.25 DTE IETFCurrent encapsulation protocol of this interface is X.25 protocol. X.25 works inDTE mode, and the data packet encapsulation format is IETF

address isX.121 address of this X.25 interface; this field will be empty if there is noaddress

state Current status of this X.25 interface

moduloData packets and flow control packets sent by this X.25 interface arenumbered in modulo 8 mode

input/output : window sizes ...Flow control parameters of this X.25 interface, including receiving windowsize, sending window size, maximum received packet length (in bytes), andmaximum sent packet length (in bytes)

Channels :Channel range division of this X.25 interface, sequentially as incoming-onlychannel section, two-way channel section, outgoing-only channel section; if both demarcating values of an section are 0, this section is disabled

Timers : Delay values of various timers of this X.25 interface, in unit of second

New ConfigurationNew configuration of this X.25 interface taking effect after next restart; if thisconfiguration is wrong, the default value will be restored

Restarts 0 ( Restart Collision 0)Statistics information of this X.25 interface: times of restart (including restartcollision)

Refused Incoming Call Statistics information of this X.25 interface: times of call refusalsFailing Outgoing Call Statistics information of this X.25 interface: times of call failures

input/output : RESTART 0/0 ...REJ 0/0

Statistics information of this X.25 interface: quantities of received and sentpackets, format: received quantity/sent quantity

Invalid PsError statistics information of this X.25 interface: total of received data packetscarrying erroneous sequence numbers

Invalid Pr Error statistics information of this X.25 interface: total of received data packetsand flow control packets carrying erroneous acknowledgement numbers

UnknownError statistics information of this X.25 interface: total of received non-analyzable packets

4.4.3 Displaying X.25 Alias Table

Perform the following task to display all aliases of all X.25 interfaces:

Quidway# show x25 alias

Alias for Serial0:Alias for Serial1:Alias- 1: $20112405$ strict





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Alias- 2: $20112450 leftAlias- 3: 20112450$ right

The information shown above indicates: X.25 interface Serial0 is not set with an alias;X.25 interface Serial1 is set with 3 aliases: $20112405$ (matching mode is strict

matching), $20112405 (matching mode is left-justified matching), and 20112405$(matching mode is right-justified matching).

4.4.4 Displaying X.25 Address Mapping Table

Perform the following task to display all address mappings of all X.25 interfaces:

Quidway# show x25 mapSerial0: X.121 20112450 <--> ip 202.38.165.19 SVC_MAPNo VC attachedFacility:ACCEPT_REVERSE;BROADCAST;

PACKET_SIZE: I 512 O 512;Serial1: X.121 20112451 <--> ip 202.38.166.20 PVC_MAP1 VC: 3*Facility:BROADCAST;WINDOW_SIZE: I 5 O 5

The table below describes the detailed meanings of various fields of the above addressmapping information:

Table LLC-4-43 X.25 address mapping information

Field Meaning

Serial0 Name of the X.25 interface in which this address mapping is locatedX.121 20112451 Destination X.121 address of this address mapping

ip 202.38.165.19 Destination protocol type and protocol address of this address mapping

SVC_MAPType of this address mapping, SVC_MAP means temporary virtual circuit addressmapping, PVC_MAP means permanent virtual circuit address mapping

1 VC: 3*There is one virtual circuit associated with this address mapping, numbered 3; if no virtualcircuit is associated with this address mapping, this field will be "No VC attached"

FacilityOption of this address mapping, for example, "Broadcast" indicates to "permit tobroadcast through this address mapping"

4.4.5 Displaying X.25 Switching Route Table

Quidway(config)# Show X25 routeNumber X.121 CUD FowardTo# 1 1 Serial0# 2 2 Serial1

The information above means that the call with a destination X.121 address of 1 will be

switched to interface Serial0 for output; and the call with a destination X.121 address of 2 will be switched to interface Serial1 for output.

4.4.6 Displaying X.25 Virtual Circuit Table

Perform the following task to display all the current virtual circuits of all X.25 interfaces:

Quidway# show x25 vc





4-33

SVC 1, State: TRANSFER, Interface: Serial0Started: 1998-1-1 1:48:11, Last input: 0:45:57, Last output: 0:45:59Connects: X.121 20112450 <--> ip 202.38.165.19Window size: input 5 output 5Packet Size: input 128 output 128

PS: 0 PR: 0 ACK: 0 Remote PR: 0 RCNT: 0RNR: FALSE Reset times: 0input/output: DATA 1154/1022 INTERRUPT 0/0 Bytes 1569732/1435638RR 143/165 RNR 0/0 REJ 0/0Snd Queue: Current length 0 Max length 50 Drops 0Rcv Queue: Current length 0 Max length 50 Drops 0PVC 3, State: TRANSFER, Interface: Serial1Started: 1998-1-1 1:48:11, Last input: 0:30:09, Last output: 0:30:17Connects: X.121 20112451 <--> ip 202.38.166.20Window size: input 5 output 5Packet Size: input 128 output 128PS: 0 PR: 0 ACK: 0 Remote PR: 0 RCNT: 0RNR: FALSE Reset times: 0input/output:DATA 0/0 INTERRUPT 0/0 Bytes 0/0RR 0/0 RNR 0/0 REJ 0/0Snd Queue: Current length 0 Max length 50 Drops 0Rcv Queue: Current length 0 Max length 50 Drops 0

The information above indicates that on the X.25 interface Serial0, there is onetemporary virtual circuit numbered 1; on the X.25 interface Serial1, there is onepermanent virtual circuit numbered 3. The following table shows the detailed meaningof each field of the above information.

Table LLC-4-44 X.25 virtual circuit information

Field Meaning

SVC 1Type and number of this virtual circuit; SVC means temporary virtual circuit, and PVCmeans permanent virtual circuit

State Current status of this virtual circuit

Interface Name of interface where this virtual circuit is locatedStarted Time when this virtual circuit is set up, format: year-month-day h: m: s

Last inputTime interval from last receipt of data packet on this virtual circuit till now (executing theshow x25 vc command), format: hh:mm:ss

Last outputTime interval from last sending of data packet on this virtual circuit till now (executing theshow x25 vc command), format: hh:mm:ss

Connects

If the router is the start or end point for a data transmission (i.e., the router does not work inX.25 switching mode), this field refers to the address mapping associated with this virtualcircuit. If this virtual circuit is set up for switching (i.e., the router works in the switchingmode), this field indicates the type and number of virtual circuit on another X.25 interfaceassociated with this virtual circuit. For example, "Serial1 SVC 1024" indicates this virtualcircuit is associated with the temporary virtual circuit 1024 on the X.25 interface Serial1

Window size Receiving window size and sending window size of this virtual circuit

Packet size Maximum lengths of receiving packet and sending packet of this virtual circuit

Vs Current sending variable of this virtual circuitVr Current receiving variable of this virtual circuit

ACK Current acknowledgement variable of this virtual circuit

Remote Vr Last acknowledgment received from the peer by this virtual circuit

RCNT Quantity of data packets sent by this virtual circuit but not yet acknowledged by the peer

RNRWhether this virtual circuit currently is in the status "receiving not ready"; TRUE means it isin this status, while FALSE means not

Reset times Times of resetting of this virtual circuit

input/output:DATA ... REJ 0/0

Statistics information of this virtual circuit, including quantities of received and sent packetsand total bytes of all data packets

Snd QueueCurrent status of the sending queue of this virtual circuit: maximum holding length, currentqueue length, quantity of data packets lost due to full queue

Rcv QueueCurrent status of the receiving queue of this virtual circuit: maximum holding length, currentqueue length, quantity of data packets lost due to full queue





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4.5 Typical LAPB Configuration Example


Two routers are directly connected via serial ports with LABP protocol encapsulated totransmit IP data packets directly.


V.35 cable

Serial 0 Serial 1Router Router

Figure LLC-4-9 Direct connection between two routers via serial ports


As shown in the diagram above, perform the following configuration tasks:


! Select interface

Quidway# configure


! Specify IP address for this interface

Quidway(config-if-Serial0)# ip address 202.38.160.1 255.255.255.0! Encapsulate this interface as LAPB interface and specify its working mode as DTE

Quidway(config-if-Serial0)# encapsulation lapb dte

! Configure other Lapb parameters (if the link is of good quality, and a higher rate is

required, the flow control parameter modulo can be increased to 128, k to 127, but theymust be the same for both ends in the direct connection)

Quidway(config-if-Serial0)# lapb module 128

Quidway(config-if-Serial0)# lapb k 127


! Select interface

Quidway# configure




! Encapsulate this interface as LAPB interface and specify its working mode as DCE

Quidway(config-if-Serial1)# encapsulation lapb dce





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! Configure other LAPB parameters (if the link quality is good, and a higher rate isrequired, the flow control parameter modulo can be increased to 128, k to 127, but theymust be the same for both ends in the direct connection)

Quidway(config-if-Serial1)# lapb modulo 128Quidway(config-if-Serial1)# lapb k 127

4.6 Typical X.25 Configuration Example

This section describes some typical X.25 configuration examples.

4.6.1 Back to Back Direct Connection of Two Routers via Serial Ports


As shown in the diagram below, if two routers are to be directly connected back to back,

the X.25 protocol is encapsulated between the serial ports for IP data packettransmission, configure the two routers as follows.


V.24/V.35 cable

Router Serial 1Serial 0 Router

Figure LLC-4-10 Direct connection of two routers via serial ports



! Select interface

Quidway# configure




! Encapsulate this interface as X.25 interface and specify its working mode as DTE

Quidway(config-if-Serial0)# encapsulation x25 dte

! Specify X.121 address of this interface

Quidway(config-if-Serial0)# x25 address 20112451

! Specify address mapping to the peer

Quidway(config-if-Serial0)# x25 map ip 202.38.160.2 20112452

! As this is a direct connection, the flow control parameters can be increased slightly

Quidway(config-if-Serial0)# x25 ips 1024





4-36

Quidway(config-if-Serial0)# x25 ops 1024

Quidway(config-if-Serial0)# x25 win 5

Quidway(config-if-Serial0)# x25 wout 5


! Select interface

Quidway# configure




! Encapsulate this interface as X.25 interface and specify its working mode as DCE


! Specify X.121 address of this interface


! Specify address mapping to the peer


! As this is a direct connection, the flow control parameters can be increased slightly





4.6.2 Connecting the Router to X.25 Public Packet Network


As shown in the diagram below, three routers A, B and C are connected to the sameX.25 network for mutual communication. The requirements are:

l IP addresses of the interfaces Serial0 of three routers are 168.173.24.1,168.173.24.2 and 168.173.24.3 respectively.

l X.121 addresses assigned to the three routers by the network are 30561001,30561002 and 30561003 respectively.

l Standard window size supported by the packet network: both receiving windowand sending window are 5.

l Standard maximum packet length: both maximum receiving packet length andmaximum sending packet length are 512.

l Channel range: permanent virtual circuit section, incoming-only channel sectionand outgoing-only channel section are disabled, two-way channel section is [1,31].





4-37


RouterA

RouterB

RouterC

Serial0

Serial0

Serial0

IP: 168.173.24.1X.121: 30561001

IP: 168.173.24.2X.121: 30561002

X.25 windowsize: 5 5

packetsize: 512 512

Figure LLC-4-11 Connect the router to X.25 public packet network



! Configure interface IP address

Quidway# configure

Quidway(config)# interface Serial 0


! Connect to public packet network, make the router as DTE side







Quidway(config-if-Serial0)# x25 htc 32





Quidway# configure









4-38









l Configure Router C:


Quidway# configure













4.6.3 Configuring Virtual Circuit Range


The router's interface Serial0 is encapsulated into X.25 protocol, with the virtual circuitrange: permanent virtual circuit section [1, 8], incoming-only channel section [9, 16],two-way channel section [17, 1024], and the outgoing-only channel section is disabled.

II. Configuration procedure

Quidway# configure








4-39



4.6.4 Transmitting IP Datagram via X.25 PVC


In the following diagram, the permanent virtual circuit section allowed by the packetnetwork is [1,8], the PVC numbers assigned to Router A and Router B are 3 and 4respectively. The IP network addresses of Ethernets A and B are 202.38.165.0 and196.25.231.0 respectively. It is required to exchange routing information betweenEthernets A and B with RIP routing protocol, so that PC A and PC B can exchangeinformation without adding static route.


X.25

windowsize: 5 5

packetsize: 512 512RouterA RouterB

IP: 192.149.13.1

X.121: 1004358901

IP: 192.149.13.2

X.121: 1004358902

PVC 3 PVC 4

EtherNet A EtherNet B

PC BPC A

Serial 0 Serial 0

Figure LLC-4-12 X.25 PVC bearing IP data packet



Quidway# configure

Quidway(config)# interface ethernet 0

Quidway(config-if-Ethernet0)# ip address 202.38.165.1 255.255.255.0

Quidway(config-if-Ethernet0)# interface serial 0





Quidway(config-if-Serial0)# x25 pvc 3 ip 192.149.13.2 1004358902 broadcastpacketsize 512 512 windowsize 5 5


Quidway(config)# router rip






4-40

Quidway# configure

Quidway(config)# interface ethernet 0

Quidway(config-if-Ethernet0)# ip address 196.25.231.1 255.255.255.0

Quidway(config-if-Ethernet0)# interface serial 0





Quidway(config-if-Serial0)# x25 pvc 4 ip 192.149.13.1 1004358901 broadcastpacketsize 512 512 windowsize 5 5


Quidway(config)# router rip

In above configuration, the permanent virtual circuit numbers of routers A and B are

different: 3 and 4 respectively. Virtual circuit refers to the end-to-end logic link betweenthe calling DTE and the called DTE, while logic channel refers to the logic link betweentwo directly connected devices (either between DTE and DCE, or between the ports of two packet switching exchanges). A virtual circuit consists of several logic channels,and each logic channel has a separate number. The virtual circuit between routers Aand B is shown in Figure 4-12 (suppose this virtual circuit passes four packet switchingexchanges in the network).

RouterA

RouterB

PBX

PBX

PBX

LC 3

LC 4

LC 243

LC 24

LC 3

PBX

Figure LLC-4-13 A virtual circuit consisting of several logic channels

Therefore, the PVC 3 and PVC 4 mentioned above actually refer to the numbers of the

logic channels between the router and the switch directly connected to it. However, onone side of this virtual circuit, the logic channel number can be used to identify thisvirtual circuit without causing misunderstanding. This is why no strict distinction ismade between "virtual circuit" and "logic channel".





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4.6.5 Typical X.25 Sub-Interface Configuration Example


Multiple sub-interfaces are configured on a physical interface to connect with multiplepeers of different network sections. In the following diagram, Router A is configuredwith two sub-interfaces, respectively interconnected with Router B and Router C.


S0

S0

S0 S0

S2

RouterB RouterC

RouterD

RouterA

S1

Figure LLC-4-14 Diagram of X.25 sub-interface configuration



Quidway# configure




Quidway(config-if-Serial0)# interface serial 0.1

! Create sub-interface serial 0.1

Quidway(config-if-Serial0.1)# ip address 10.1.1.2 255.255.0.0

Quidway(config-if-Serial0.1)# x25 map ip 10.1.1.1 200

! Create sub-interface serial 0.2

Quidway(config-if-Serial0.1)# interface serial 0.2

Quidway(config-if-Serial0.2)# ip address 20.1.1.2 255.255.0.0

Quidway(config-if-Serial0.2)# x25 map ip 20.1.1.1 300


Quidway# configure










4-42

Quidway# configure





l Configure Router D:

Quidway# configure



Quidway(config-if-Serial0)# interface serial 1


Quidway(config-if-Serial1)# interface serial 2







4.6.6 SVC Application of XOT


Router B and C connect through Ethernet interface, and build TCP connection betweenthem. X.25 packets forward through TCP, and configure SVC to implement the SVCfunction.

II.Networking diagram

PC1

S0

S0

S0

S0

E0

E0

PC2

E0 E0

Router B

Router A

Router C

Router D

Figure LLC-4-15 SVC application networking diagram of XOT





4-43


l Configure Quidway A router

! Basic X.25 Configuration

QuidwayA# config

QuidwayA(config)# interface serial 0

QuidwayA(config-if-Serial0)# encapsulation x25 dte ietf

QuidwayA(config-if-Serial0)# x25 address 1

QuidwayA(config-if-Serial0)# x25 map ip 1.1.1.2 2

QuidwayA(config-if-Serial0)# ip address 1.1.1.1 255.0.0.0

l Configure Quidway D router


QuidwayD# config

QuidwayD(config)# interface serial 0

QuidwayD(config-if-Serial0)# encapsulation x25 dte ietf

QuidwayD(config-if-Serial0)# x25 address 2

QuidwayD(config-if-Serial0)# x25 map ip 1.1.1.1 1

QuidwayD(config-if-Serial0)# ip address 1.1.1.2 255.0.0.0

l Configure Quidway B router

! Start X.25 switching

QuidwayB# config

QuidwayB(config)# x25 routing

! Configure X.25 local switching

QuidwayB(config)# x25 route 1 interface serial 0

! Configure XOT switching

QuidwayB(config)# x25 route 2 xot 10.1.1.2

! Configure ethernet 0.

QuidwayB(config)# interface ethernet 0

QuidwayB(config-if-Ethernet0)# ip address 10.1.1.1 255.0.0.0

! Configure Serial 0

QuidwayB(config)# interface serial 0

QuidwayB(config-if-Serial0)# encapsulation x25 dce ietf

l Configure Quidway C router


QuidwayC# config

QuidwayC(config)# x25 routing





4-44

! Configure X.25 local switching

QuidwayC(config)# x25 route 2 interface serial 0

! Configure XOT switching

QuidwayC(config)# x25 route 1 xot 10.1.1.1

! Configure Ethernet 0

QuidwayC(config)# interface ethernet 0

QuidwayC(config-if-Ethernet0)# ip address 10.1.1.2 255.0.0.0

! Configure Serial 0

QuidwayC(config)# interface serial 0

QuidwayC(config-if-Serial0)# encapsulation x25 dce ietf

4.6.7 PVC Application of XOT


Router B and C connect through Ethernet interface, and build TCP connection betweenthem. X.25 packets forward through TCP, and configure PVC to implement the PVCfunction.

II.Networking diagram

PC1

S0

S0

S0

S0

E0E0

PC2

E0 E0

Router B

Router A Router D

Router C

Figure LLC-4-16 PVC application networking diagram of XOT

III.Configuration procedure

l Configure Quidway A router


QuidwayA# config

QuidwayA(config)# interface serial 0

QuidwayA(config-if-Serial0)# encapsulation x25 dte ietf

QuidwayA(config-if-Serial0)# x25 address 1

QuidwayA(config-if-Serial0)# x25 lic 10





4-45

QuidwayA(config-if-Serial0)# x25 hic 20

QuidwayA(config-if-Serial0)# x25 ltc 30

QuidwayA(config-if-Serial0)# x25 pvc 1 ip 1.1.1.2 2

QuidwayA(config-if-Serial0)# ip address 1.1.1.1 255.0.0.0

l Configure Quidway RouterD

! Basic X.25 configuration

QuidwayD# config

QuidwayD(config)# interface serial 0

QuidwayD(config-if-Serial0)# encapsulation x25 dte ietf

QuidwayD(config-if-Serial0)# x25 address 2

QuidwayD(config-if-Serial0)# x25 lic 10

QuidwayD(config-if-Serial0)# x25 hic 20

QuidwayD(config-if-Serial0)# x25 ltc 30

QuidwayD(config-if-Serial0)# x25 pvc 1 ip 1.1.1.1 1

QuidwayD(config-if-Serial0)# ip address 1.1.1.2 255.0.0.0

l Configure Quidway B router


QuidwayB# config

QuidwayB(config)# x25 routing

! Configure Ethernet 0.

QuidwayB(config)# interface ethernet 0

QuidwayB(config-if-Ethernet0)# ip address 10.1.1.1 255.0.0.0

! Configure Serial 0.

QuidwayB(config)# interface serial 0

QuidwayB(config-if-Serial0)# encapsulation x25 dce ietf

QuidwayB(config-if-Serial0)# x25 lic 10

QuidwayB(config-if-Serial0)# x25 hic 20

QuidwayB(config-if-Serial0)# x25 ltc 30

QuidwayB(config-if-Serial0)# x25 pvc 1 xot 10.1.1.2 interface serial 0 pvc 1

l Configure Quidway C router


QuidwayC# config

QuidwayC(config)# x25 routing

! Configure Ethernet 0.

QuidwayC(config)# interface ethernet 0





4-46

QuidwayC(config-if-Ethernet0)# ip address 10.1.1.2 255.0.0.0

! Configure Serial 0.

QuidwayC(config)# interface serial 0

QuidwayC(config-if-Serial0)# en x25 DCE IETF

QuidwayC(config-if-Serial0)# x25 lic 10

QuidwayC(config-if-Serial0)# x25 hic 20

QuidwayC(config-if-Serial0)# x25 ltc 30

QuidwayC(config-if-Serial0)# x25 pvc 1 xot 10.1.1.1 interface serial 0 pvc 1

4.7 Fault Diagnosis and Troubleshooting of LAPB

Fault 1: Two connected sides are encapsulated with X.25 (or directly encapsulated withLAPB), but the protocol is always disconnected. Turn on the debugging switch, it isfound that one end sends SABM frame, while the other end sends FRMR framecircularly.

Troubleshooting: this is because both sides are encapsulated in the same workingmode (DTE or DCE). Change the working mode of one side to solve the problem.

Fault 2: Two connected sides are encapsulated with X.25, and the protocol is already in

UP status, but cannot ping through the peer. Turn on the debugging switch and it isfound that the received frames are discarded on one end instead of being forwarded upto the packet layer.

Troubleshooting: The maximum frame bits of this end may be too small. Change the

configuration.

4.8 Fault Diagnosis and Troubleshooting of X.25

This section describes some common faults and the troubleshooting methods.

Assuming that the connection of the X.25 layer 2 (LAPB) is completely correct.

Fault 1: LAPB is already in "Connect" status, but the X.25 protocol can not enter "UP"status.

Troubleshooting: It is possible that the local working mode has been configured wrong,

for example, both sides of a connection are DTE or DCE. Try again after changing theencapsulation working mode.

Fault 2: X.25 protocol is "UP", but virtual circuit can not be established, i.e., unable toping through.

This may be caused by one of the following:

l Local X.121 address not configuredl Address mapping to the peer not configuredl Opposite X.121 address not configuredl Address mapping from peer to local not configuredl Channel range not correctl Facility options inhibited by network have been carried.





4-47

Troubleshooting: if the address is configured incorrectly, change the configuration. For the last two causes, please consult the network management department for correctchannel range and permissible facility options.

Fault 3: the virtual circuit can be set up, but is frequently reset or cleared during datatransmission.

Troubleshooting: It is very likely that the flow control parameters are set incorrectly. For the back to back direct connection, check the sending window and receiving window of the local and peer to see whether they match each other. In case it is connected topublic packet networks, consult the network management department. about correctflow control parameters.

Fault 4: the request to set Permanent virtual circuits (PVCs) is rejected.

Troubleshooting: if the channel section of the permanent virtual circuit is disabled, the

X.25 will reject the request to set a permanent virtual circuit. In this case, simply enablethe permanent virtual circuit channel section.

Fault 5: after configuring SVC application of XOT, you cannot ping through

Troubleshooting: there are various reasons. You may first check if the physical andprotocol statuses of the interface are UP. If the interface status is DOWN, check if thephysical connection and bottom configuration are correct. If the interface is properlyconfigured, then check the SVC configuration. If SVC is also properly configured, checkthe XOT configuration.

Fault 6: after configuring PVC application of XOT, you cannot ping through

Troubleshooting: there are various reasons. You may first check if the physical and

protocol statuses of the interface are UP. If the interface status is DOWN, check if thephysical connection and bottom configuration are correct. If the interface is properly

configured, then check the PVC configuration. If PVC is also properly configured, checkthe XOT configuration.




Chapter 5Configuring Frame Rela

5-1

Chapter 5 Configuring Frame Relay

5.1 Frame Relay Protocol Overview

Frame-Relay protocol is a fast-packaging switching technology, which develops on thebasis of X.25 technology. Compared with X.25 protocol, Frame-Relay only implementsthe core function of the link layer, easily and efficiently.

A frame relay network provides capacity of data communication between user

equipment (such as routers and hosts), also called data terminal equipment (DTE). Theequipment that provides access for DTE is data circuit-terminating equipment (DCE). Aframe relay network can be a public network, a private enterprise network, or a network

formed by direct connection between data equipment.

The frame relay protocol is a statistics multiplexing protocol, providing multiple virtualcircuits on a single physical transmission line. Each virtual circuit is identified by a DLCI(Data Link Connection Identifier), which is valid only on the local interface and thecorresponding opposite interface. This means that in the same frame relay network, thesame DLCI on different physical interfaces does not indicate the same virtualconnection. A user interface in the frame relay network supports up to 1024 virtualcircuits, among which the DLCI range available to the user is 16~1007. As a framerelay virtual circuit is connection oriented, different local DLCIs are connected todifferent opposite equipment. Therefore, the local DLCI can be considered as the"frame relay address" of the opposite equipment.

Frame relay address mapping associates the opposite equipment’ s protocol addresswith its frame relay address (local DLCI), so that the upper layer protocol can locate theopposite equipment by using its protocol address. Frame relay mainly bears IP. Insending IP message, only the next hop address of the message can be obtained fromthe route table, so this IP address must be used to determine the corresponding DLCIbefore sending. This process can be performed by searching for the frame relayaddress mapping table, because the mapping relation between the opposite IPaddress and the next hop DLCI is stored in the address mapping table. The addressmapping table can be manually configured, or maintained dynamically by the Inverse ARP protocol.

Virtual circuits can be divided into permanent virtual circuit and switching virtual circuit,according to their different configuration method. Virtual circuits configured manuallyare called Permanent virtual circuits (PVCs), and those created by protocol negotiation

are called switching virtual circuits, which are automatically created and deleted byInverse ARP protocol. At present, the most frequently used in frame relay is thepermanent virtual circuit mode, i.e., manual configured virtual circuit.

In the permanent virtual circuit mode, test the availability of the virtual circuit, which is

accomplished by the local management interface (LMI) protocol. VRP supports threeLMI protocols: LMI complying with ITU-T Q.933 Appendix A, LMI complying with ANSIT1.617 Appendix D and Gang of Four LMI (also called Cisco LMI). Their basic workingmode is: DTE sends one Status Enquiry message to query the virtual circuit status atcertain interval, after the DCE receives the message, it will immediately use the Statusmessage to inform DTE the status of all the virtual circuits on current interface.

The status of Permanent virtual circuits (PVCs) on DTE is completely determined by

DCE. And the network determines the status of Permanent virtual circuits (PVCs) of





5-2

DCE. In case that the two network devices are directly connected, the equipmentadministrator sets the virtual circuit status of DCE. In VRP, the quantity and status of the virtual circuits are set at the same time when address mapping is set (with theframe-relay map command). They can also be configured with the frame relay local

virtual circuit configuration command (frame-relay local-dlci) or inter-frame relay sub-interface virtual command (frame-relay interface-dlci).

5.2 Configuring Frame Relay

5.2.1 Frame Relay Configuration Task List

The frame relay configuration task list is as follows:

l Configuring Interface Encapsulation as Frame Relayl Configuring Frame Relay Terminal Type

l Configuring Frame Relay LMI Typel Configuring Frame Relay Protocol Parametersl Configuring Frame Relay Address Mappingl Configuring Frame Relay Local Virtual Circuitl Configuring Frame Relay Sub-Interfacel Configuring Frame Relay PVC Switchingl Enable/Disable TCP/IP Header Compression on Interfaces

5.2.2 Configuring Interface Encapsulation as Frame Relay

In the interface configuration mode, perform the following task to configure the interfaceencapsulation as frame relay.

Table LLC-5-1 Configure interface encapsulation as frame relay

Operation Command

Configure interface encapsulation as frame relay encapsulatio n frame-relay [cisco-compatibl e | ietf ]

By default, the interface is encapsulated with link layer protocol PPP and the defaultencapsulating format is ietf.

Note the following points:

1) The interface can be encapsulated with Frame-Relay only when it operates in thesynchronous mode.

2) When SLIP is encapsulated on the interface, the physical attributes of theinterface cannot be modified to synchronous mode. At this time, you should firstmodify the link layer encapsulation of the interface to PPP and then you maychange the interface attribute to synchronous mode.

3) After the interface is encapsulated with Frame-Relay its upper layer still can carryIP and IPX protocols.





5-3

& Note:

1) In VRP, the IETF standard can be selected to encapsulate the frame relay protocol in the formatstipulated in RFC1490. The format compatible with CISCO router dedicated encapsulation format can also

be selected.2) The default encapsulation format is ietf encapsulation.3) The frame relay interface can send the message in either of the encapsulation formats, while it canrecognize and receive messages in both formats. That is, even if the encapsulation format of frame relayof opposite equipment is different from that of the local, the equipment at the two ends can communicatewith each other as long as the opposite equipment can recognize the two formats automatically. But whenthe opposite equipment can not recognize the two formats automatically, the frame relays of equipment atthe two ends must be set to the same format.

5.2.3 Configuring Frame Relay Terminal Type

In frame relay, the two sides in communication are classified into user side and network

side. The user side is called DTE, and the network side is called DCE. The equipmentresponse interface should be configured as DTE or DCE format according to itslocation in the network. In frame relay networks, Network-to-Network Interface (NNI) isused between the frame relay switches.

In the interface configuration mode, perform the following task to configure the type of frame relay interface as DTE, DCE or NNI.

Table LLC-5-2 Configure frame relay interface type

Operation Command

Configure frame relay interface type frame-relay intf -type { dce | dte | nni }Restore the frame relay interface type to the default value,i.e. DTE mode

no frame-relay intf-typ e

The default type of frame relay interface is DTE.

Note the following point: If the terminal type of Frame-Relay interface is changed toDCE or NNI, frame-relay switching should be enabled in the global configurationmode.

5.2.4 Configuring Frame Relay LMI Type

The LMI protocol is used to maintain the PVC lists of frame relay protocol, includingadding PVC records, deleting the records about disconnected PVCs, monitoring thechange of PVC status, and verifying the link integrity. VRP supports three standard LMIprotocols: LMI complying with ITU-T Q.933 Appendix A, LMI complying with ANSIT1.617 Appendix D and Gang of Four LMI (also called Cisco LMI)

In the interface configuration mode, perform the following task to configure the type of LMI protocol of frame relay interface.





5-4

Table LLC-5-3 Configure frame relay LMI protocol type

Operation Command

Configure frame relay LMI protocol typeframe-relay lmi-type { ansi | cisco-

compatible | q933a }

When the frame relay interface type is DCE or NNI, this command willrestore the frame relay interface LMI protocol type to the default q933a;when the frame relay interface type is DTE, this command will set theinterface and the LMI protocol type for peer negotiation.

no frame-relay lmi-typ e

When the frame relay interface type is DCE or NNI, the default type of LMI protocol of interface is Q933a.

When the frame relay interface type is DTE, the default LMI protocol of interface is null.

5.2.5 Configuring Frame Relay LMI Protocol Parameters

LMI protocol specification is as follows:

l DTE sends a Status-Enquiry message at certain interval (determined by T391).There are two types of Status-Enquiry messages: link integrity verificationmessage and link status enquiry message. Parameter N391 defines the ratio of the two types of messages sent, i.e. number of link integrity verification messages :number of link status enquiry packet messages = N391-1: 1. DTE sends aStatus-Enquiry message to query the link integrity and all the PVC status or FullSatus Message Polling.

l DCE immediately sends a Status response after receiving the message. If theDTE does not receive any response within a specified time, it will record this error.

l If the error number exceeds the threshold, DTE will regard the physical channeland all virtual circuits as unavailable. N392 and N393 together define "error threshold".

l N392 and N393 together define "error threshold". In other words, if errors reachN392 among the N393 Status-Enquiry messages sent by DTE, DTE will consider that error number has reached the threshold and the physical channel and allvirtual circuits are unavailable.

l The meanings of “ N392 and N393” of DCE are similar to those of N392 and N393of DTE. The difference is: the fixed time interval at which DCE requires DTE tosend the Status-Enquiry message is determined by T392, while that in DTE isdetermined by T391.

Frame relay protocol parameters and their configurations are respectively shown in

Table LLC-5-4 and LLC-5-5.

Table LLC-5-4 Meanings of frame relay protocol parameters

Working mode Meaning of parameter Value range Default value

Request PVC status counter (N391) 1~255 6Error threshold (N392) 1~10 3

Event counter (N393) 1~10 4DTE

User side polling timer (T391), the value 0indicates that LMI protocol is disabled

0~32767(Unit: second)

10(Unit: second)

Error threshold (N392) 1~10 3Event counter (N393) 1~10 4

DCE

Network side polling timer (T392)5~30(Unit: second)

15(Unit: second)





5-5

These parameters are stipulated by Q.933 Appendix A, with the meanings as follows:

Meanings of parameters related to DTE working mode:

l T391DTE: the interval of link full status message polling of the devices at the DTE

sidel N391: DTE sends a Status-Enquiry message at certain interval (determined by

T391). There are two types of Status-Enquiry messages: link integrity verificationmessage and link status enquiry message. Parameter N391 defines the ratio of the two types of messages sent, i.e. number of link integrity verification messages :number of link status enquiry packet messages = N391-1: 1

l N392DTE: it indicates the threshold for errors among the observed events.l N393DTE: it indicates the total of observed events.

DTE sends a Status-Enquiry message at certain interval (determined by T391) to querythe link status. DCE immediately sends a Status response after receiving the message.If the DTE does not receive any response within a specified time, it will record this error.If the error number exceeds the threshold, DTE will regard the physical channel and allvirtual circuits as unavailable. N392 and N393 together define "error threshold". In

other words, if errors reach N392 among the N393 Status-Enquiry messages sent byDTE, DTE will consider that error number has reached the threshold and the physicalchannel and all virtual circuits are unavailable.

Meanings of parameters related to DCE working mode:

l T392DCE: a time variable, which defines the maximum time for DCE to wait for one Status-Enquiry message and should be larger than T391.

l N392DCE: it indicates the threshold for errors among the observed events.l N393DCE: it indicates the total of observed events.

Note the following points: N392 should be less than or equal to N393 and T391DTEshould be less than the peer T392DCE.





5-6

Table LLC-5-5 Configure frame relay protocol parameters

Operation Command

Configure user side N391 frame-relay lmi-n391dte n391-value

Restore user side N391 to the default value no frame-relay lmi-n391dte

Configure user side N392 frame-relay lmi-n392dte n392-valueRestore user side N392 to the default value no frame-relay lmi-n392dte

Configure user side N393 frame-relay lmi-n393dte n393-value

Restore user side N393 to the default value no frame-relay lmi-n393dte

Configure user side T391 keepalive t391-valueDisable LMI protocol no keepalive

Configure network side N392 frame-relay lmi-n392dce n392-value

Restore network side N392 to the default value no frame-relay lmi-n392dce

Configure network side N393 frame-relay lmi-n393dce n393-valueRestore network side N393 to the default value no frame-relay lmi-n393dce

Configure network side T392 frame-relay lmi-t392dce t392-value

Restore network side T392 to the default value no frame-relay lmi-t392dce

& Note:

N392 should be less than or equal to N393, and T391 should be less than T392 of the peer.

5.2.6 Configuring Frame Relay Address Mapping

Frame-Relay address mapping means to establish the mapping between the peer

protocol address and the local DLCI. Address mapping of frame relay can either beconfigured statically or set up dynamically.

I. Configure frame relay static address mapping

Static configuration means the manual setup of the mapping relation between the peer

protocol address and local DLCI, and is usually applied when there are few peer hostsor there is a default route.

In interface configuration mode, perform the following task to configure the frame relaystatic address mapping.

Table LLC-5-6 Configure frame relay static address mapping

Operation Command

Add a static address mappingframe-relay map { ip | ipx } protocol-address dlci [ broadcast ][ ci sco-compatible | ietf ] [ lin logical-number ] [ nocompress |tcp header-compress [active | passive ] ]

Delete a static address mapping no frame-relay map [IP|IPX] protocol-address dlci

By default, the dynamic inverse arp is enabled on all the interfaces.

After the frame relay static address mapping is configured, the dynamic inverse arp willbe disabled automatically on the specified DLCI.





5-7

II. Configure frame relay dynamic inverse arp

Dynamic setup means the dynamic setup of mapping relation between peer protocoladdress and local DLCI after running the inverse address resolution protocol (Inverse

ARP), which is applied when the peer router also supports the "inverse addressresolution protocol" and network is complex.

In interface configuration mode, perform the following task to configure the dynamicinverse arp of frame relay.

Table LLC-5-7 Configure frame relay dynamic address mapping

Operation Command

Enable dynamic address mapping frame-relay inverse-arp [ i p | ipx ] [ dlci ]

Disable dynamic address mapping no frame-relay invers e-arp [ ip | ipx ] [ dlci ]

By default, the dynamic inverse arp is enabled on the interface.

5.2.7 Configuring Frame Relay Local Virtual Circuit

In the interface configuration mode, perform the following task to configure the framerelay local virtual circuit.

Table LLC-5-8 Configure frame relay local virtual circuit

Operation Command

Specify a virtual circuit for main interface frame-relay lo cal-dlci dlci

Cancel the virtual circuit specified for main interface no fr ame-relay local-dlci dlci

Assign virtual circuit to interface frame-relay interface-dlci dlciCancel virtual circuit assigned to interface no frame-relay i nterface-dlci dlci

& Note:

1) The command frame-relay interface-dlci dlci can be used to specify virtual circuits for main interface andsub-interface, while the command frame-relay local-dlcidlci can only be used to specify virtual circuits for main interface.2) The number of virtual circuit specified using any of the above commands should be unique, with thevalue range between 16 and 1007, i.e. the virtual circuit number is unique on a physical interface.3) When the frame relay interface type is DCE or NNI, the interface (either main interface or sub-interface)should be configured manually with virtual circuits. When the frame relay interface type is DTE, for the

main interface, the system will determine the virtual circuit automatically according to the oppositeequipment; the sub-interface must be configured with virtual circuits manually.

5.2.8 Configuring Frame Relay Sub-Interface

The Frame-Relay interface is a kind of NBMA (Non-Broadcast Muti-Access) interface,which supports sub-interfaces. The frame relay module has two types of interfaces:main interface and sub-interface. The sub-interface is of logical structure and can beused to configure protocol address and virtual circuit PVC. One physical interface caninclude multiple sub-interfaces, which do not exist physically. However, for the network





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layer, both the sub-interface and main interface can be used to configure the PVC toconnect to remote equipment.

The sub-interface of frame relay falls into two types: point-to-point sub-interface, used

to connect a single remote object and point-to-multipoint sub-interface, used to connectmultiple remote objects in the same network segment. Multiple PVCs can beconfigured on one point-to-multipoint sub-interface, and a MAP (address mapping) isset up between each PVC and the connected remote protocol address. In this way,different PVCs can reach different remotes without confusion. MAP can be set up withmanual configuration or set up dynamically using inverse address resolution protocol.Point-to-point sub-interface is applied similarly, where one sub-interface is connectedto one opposite equipment only, and the opposite equipment can be determineduniquely by configuring a PVC on the sub-interface, without configuring a MAP.

1) Creating Sub-Interface

In the interface configuration mode, perform the following task to create a sub-interface.

Table LLC-5-9 Create frame relay sub-interface

Operation Command

Enter interface configuration mode (globalconfiguration mode or interface configuration mode)

interface type number

Configure interface encapsulation as frame relay encapsulati on frame-relay

Clear IP address configuration of main interfaceinterface type number .subinterface-number [multipoint |point-to-point ]

Create sub-interface no interface type number .subinterface-number

2) Configuring virtual circuit of frame relay sub-interface

In interface configuration mode, perform the following task to configure the virtual

circuit of frame relay sub-interface.

Table LLC-5-10 Configure virtual circuit of frame relay sub-interface

Operation Command

Configure a virtual circuit frame-relay interface-dlci dlciRemove a virtual circuit no frame-relay interface-dlci

3) Configuring Sub-Interface PVC and Establish Address Mapping

Since there is only one peer address for point-to-point sub-interface, the peer address

is determined when a PVC is configured for the sub-interface. For point-to-multipointsub-interface, the peer address and local DLCI can be determined by configuring staticaddress mapping or using inverse address resolution protocol.

l Establishing static address mapping of frame relay sub-interface

Table LLC-5-11 Establish static address mapping

Operation Command

Establish address mapping frame-relay map [i p |ipx] protocol-address dlci [option ]

Delete an address mappingno frame-relay map [ip |ipx] protocol-address dlci[option]

l Applying dynamic address mapping to the sub-interface





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Table LLC-5-12 Configure frame relay dynamic address mapping

Operation Command

Enable dynamic address mapping frame-relay inverse-arp [ip |ipx] [ dlci ]

Disable dynamic address mapping no frame-relay invers e-arp [ip |ipx] [dlci ]

By default, all the sub-interfaces are enabled to use dynamic inverse-arp.

5.2.9 Configuring Frame Relay PVC Switching

Perform the following task to configure frame relay PVC switching. “ Enable/disableframe relay PVC switching” is executed in global configuration mode, while all the other commands are executed in interface configuration mode.

Table LLC-5-13 Configure frame relay PVC switchingOperation Command

Enable frame relay PVC switching frame-relay switching

Disable frame relay PVC switching no frame-relay switching

Set the interface type of frame relay performing framerelay switching to NNI or DCE. If set to DTE, the framerelay switching will be disabled

frame-relay intf-type { dce| dte | nni}

Add frame relay PVC switchingframe-relay route in-dlci interface out-interface

out-dlci

Delete frame relay PVC switching no frame-relay ro ute in-dlci

& Note:1) PVC switching will be enabled only when the type of frame relay interface configured with PVCswitching is NNI or DCE.2) PVC switching will be enabled only when two or more interfaces of the equipment for the frame relayswitching are configured.3) A PVC switching route should be configured after the PVC switching is enabled on the Frame-RelayDCE or NNI interface.

5.2.10 Enable/Disable TCP/IP Header Compression on Interfaces

Frame relay supports TCP/IP header compression. Only when the encapsulation form

of interface frame relay is cisco-compatible, can TCP/IP header compression beexecuted. TCP/IP header compression can be designated both on the interface and onconfiguring static address mapping.

Perform the following task in synchronous interface configuration mode.

Table LLC-5-14 Enable/Disable TCP/IP Header Compression on Interfaces

Operation Command

Enable TCP/IP Header Compression on Interfaces frame-relay ip tcp head-compress [ passi ve ]

Disable TCP/IP Header Compression on Interfaces no frame-relay ip tcp head-compress





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By default, interfaces use initiative compression.

5.3 Monitoring and Maintenance of Frame Relay

In privileged mode, perform the following tasks to monitor the status of frame relay inreal time.

Table LLC-5-15 Frame relay monitoring and maintenance

Operation Command

Show frame relay protocol status of each interface show frame-relay status

Show protocol address and frame relay address mappingtable

show fr ame-relay map

Show receiving/sending statistics information of frame relayLMI type messagesEither all the information or the information of specified

interface can be shown. Only the main interface can bespecified.

show frame-relay lmi [interface interface-typenterface-number ]

Show frame relay data receiving/sending statisticsinformation.Either all the information or the information of specifiedinterface can be shown. Only the main interface can bespecified.

show frame-relay packet [ interface

interface-type interface-number ]

Show frame relay permanent virtual circuit table show fr ame-relay pvc

Show frame relay PVC switching table show frame-relay route

Show statistics information of frame relay inverse addressresolution protocol messages

show frame-relay traffic

Clear all the automatically established frame relay addressmappings

clear frame-relay-inarp

Enable all the debugging of Frame-relaydebug frame-relay all [ interface interface-

type nterface-number ]Disable all the debugging of Frame-relay

no debug frame-relay all [ interface interface-type nterface-number ]

Enable the debugging of Frame-relay arpdebug frame-relay arp [ interface interface-type nterface-number ]

Disable the debugging of Frame-relay arpno debug frame-relay arp [ interface

interface-type nterface-number ]

Enable the debugging of Frame-relay eventdebug frame-relay event [ interface interface-type nterface-number ]

Disable the debugging of Frame-relay eventno d ebug frame-relay event [ interfaceinterface-type nterface-number ]

Enable the debugging of Frame-relay lmidebug frame-relay lmi [ interface interface-type nterface-number ]

Disable the debugging of Frame-relay lmino debug frame-relay lmi [ interface

interface-type nterface-number ]Enable the debugging of Frame-relay packet

debug frame-relay packet [ interfaceinterface-type nterface-number ]

Disable the debugging of Frame-relay packetno debug frame-relay packet [ interfaceinterface-type nterface-number ]

I. Displaying frame relay protocol status of each interface

Quidway# show frame-relay status

Serial0, DTE, physical up, protocol upSerial0.1, multi-point, protocol upSerial0.2, point-to-point, protocol down

Serial1, DCE, physical down, protocol down





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The above information indicates that the type of frame relay interface of serial port S0 isDTE, and both the physical layer and link layer of S0 have been activated.

II. Displaying network protocol address and frame relay address mapping

table

Quidway# show frame-relay map

Map Statistics for interface Serial0 (DTE)IP 2.2.2.2, DLCI = 33, INTERFACE = Serial0created time = 2000/04/02 00:01:58, type = static, status = inactive broadcast,vlinkIP 20.20.20.1, DLCI = 100, INTERFACE = Serial0created time = 2000/04/01 23:57:00, type = dynamic, status = active broadcast,vlinkPoint-to-Point DLCI, DLCI = 200, INTERFACE = Serial0.2created time = 2000/04/02 00:04:36, status = inactiveIP 100.100.0.1, DLCI = 280, INTERFACE = Serial0created time = 2000/04/02 00:00:57, type = static, status = inactive vlink

It can be indicated that the first address mapping is created between the PVC withDLCI=33 on the serial port S0 and the peer IP address 2.2.2.2 at 2000/04/02 00:01:58.Its type is static, i.e. it is created manually (if the type is dynamic, it indicates that it iscreated dynamically with inverse address resolution); the status is inactive, whichindicates that it is not activated and the message broadcast is permitted.

III. Displaying configuration information and statistics information of LMIprotocol

LMI protocol is used to maintain the current frame relay link status and the relatedmessages include Status Enquiry message and status message.

Quidway# show frame-relay lmi

Frame relay LMI statistics for interface Serial0 (DTE, CISCO)T391DTE = 10 (keepalive 10) N391DTE = 6, N392DTE = 3, N393DTE = 4 out statusenquiry = 96, in status = 85 status timeout = 3, discarded messages = 3Frame relay LMI statistics for interface Serial1 (DCE, ANSI)T391DTE = 0 (no keepalive)T392DCE = 15, N392DCE = 3, N393DCE = 4 in status enquiry = 0, out status = 0status enquiry timeout = 0, discarded messages = 0

The above information indicates that the type of frame relay interface of serial port S0 isDTE, LMI protocol is CISCO compatibility protocol. At DTE side, T391 is set to 10,N391 set to 6, N392 set to 3, and N393 set to 4. 96 Status Enquiry messages havebeen sent and S0, 3 status messages timeout, and 3 discarded messages havereceived 85 status messages.

IV. Displaying frame relay receiving/sending statistics information

Quidway# show frame-relay packet

Frame relay packet statistics for interface Serial0 (DTE)in packets = 84, in bytes = 1333out packets = 92, out bytes = 1217discarded in packets = 13, discarded out packets = 0Frame relay packet statistics for interface Serial1 (DCE)in packets = 0, in bytes = 0out packets = 0, out bytes = 0discarded in packets = 0, discarded out packets = 0

The above information indicates that the type of frame relay interface of serial port S0 isDTE; S0 has received 84 messages with 1333 bytes, and sent 92 messages with 1217bytes; 13 received messages are discarded and no sent message is discarded.





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V. Displaying frame relay permanent virtual circuit table

Quidway# show frame-relay pvc

PVC statistics for interface Serial0 (DTE, physical UP)

DLCI = 100, USAGE = UNUSED (0000), INTERFACE = Serial0create time = 2000/04/01 23:55:39, status = activein BECN = 0, in FECN = 0in packets = 0, in bytes = 0out packets = 0, out bytes = 0DLCI = 102, USAGE = LOCAL (0010), INTERFACE = Serial0.1create time = 2000/04/01 23:56:14, status = activein BECN = 0, in FECN = 0in packets = 0, in bytes = 0out packets = 0, out bytes = 0

The above information indicates that the PVC with DLCI=100 is unavailable and it is

configured on serial port S0. The creation time is 2000/04/01 23:55:39 and PVC isactive. No “ in FECN” message or “ in BECN” message is received; no frame is receivedor sent; and no byte is received or sent.

VI. Displaying frame relay PVC switching table

Quidway# show frame-relay route

% Frame-relay switching is onFrame relay switch statisticsIn Interface In DLCI Out Interface Out DLCI StatusSerial1 100 Serial0 100 Inactive

Meanings of fields in PVC switching table:

In Interface: input interface unit

In DLCI: input DLCI

Out Interface: output interface unit

Out DLCI: output DLCI

Status: connection status

VII. Displaying inverse address resolution protocol message statisticsinformation

Quidway# show frame-relay traffic

Frame relay InverseARP statistics for interface Serial0 (DTE)in ARP request = 0, out ARP reply = 0out ARP request = 1, in ARP reply = 1Frame relay InverseARP statistics for interface Serial1 (DCE)in ARP request = 0, out ARP reply = 0out ARP request = 0, in ARP reply = 0

The above information shows the statistics information of inverse address resolutionprotocol message.

The above information indicates that on the serial port S0, no ARP request is received,no ARP response is sent, 1 ARP request is sent, and 1 ARP response is received.





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5.4 Typical Frame Relay Configuration Example

5.4.1 Interconnecting LANs via Frame Relay Network


Interconnect LANs via the public frame relay network. In this mode, the router can onlywork as user equipment in the frame relay DTE mode.


FR

Router C

Router B

DLCI=50

DLCI=60

DLCI=80

DLCI=70

Quidway Router A

IP:202.38.163.253

IP:202.38.163.251IP:202.38.163.252

Figure LLC-5-1 Interconnect LANs via frame relay network






! Configure interface encapsulation as frame relay

Quidway(config-if-Serial1)# encapsulation frame-relay

Quidway(config-if-Serial1)# frame-relay intf-type dte

! If the opposite router supports inverse address resolution function, configure dynamicaddress mapping

Quidway(config-if-Serial1)# frame-relay inverse-arp

! Otherwise configure static address mapping

Quidway(config-if-Serial1)# frame-relay map ip 202.38.163.252 50









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! Otherwise, configure static address mapping


5.4.2 Interconnecting LANs via Private Line


Two Quidway routers are directly connected via a serial port. Router A works in theframe relay DCE mode, and Router B works in the frame relay DTE mode.


Quidway Router A Quidway Router B

IP:202.38.163.251 IP:202.38.163.252

DLCI=100

Figure LLC-5-2 Interconnect LANs via private line





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Quidway(config-if-Serial1)# frame-relay intf-type dce

! Configure local virtual circuit

Quidway(config-if-serial1) # frame-relay local-dlci 100
















5.5 Fault Diagnosis and Troubleshooting of Frame Relay

1) Fault 1: the physical layer in DOWN status.

Troubleshooting:

Check whether the physical line is normal.

Check whether the opposite equipment runs normally.

2) Fault 2: the physical layer is already UP, but the link layer protocol is DOWN.

Troubleshooting:





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Check whether both local equipment and opposite equipment have been encapsulatedwith frame relay protocol.

If two sets of equipment are directly connected, check the local equipment and

opposite equipment to see whether one end is configured as frame relay DTE interfaceand the other end as frame relay DCE interface.

If everything is OK, turn on the monitoring switch for the frame relay LMI message tosee whether the Status Enquiry messages correspond to the Status message. If not, itindicates the physical layer data is not received/sent correctly. Check the physical layer.Command debug frame-relay lmi is used to turn on the monitoring switch for framerelay LMI information.

3) Fault 3: link layer protocol is UP, but cannot Ping through the peer.

Troubleshooting:

Check whether the link layer protocols of the equipment at both ends are UP.

Check whether the equipment at both ends have configured (or created) correctaddress mapping for the peer.

Check the route table to see whether there is a route to the peer.




Chapter 6Configuring HDLC

6-1

Chapter 6 Configuring HDLC

HDLC (High Data Link Control), is a kind of bit-oriented link layer protocol. Its mostprominent feature is that it can transparently transmit any kind of bit flow without therestriction that the data must be character set. Protocols of standard HDLC protocolgroup all operate upon the synchronous serial lines, e.g., DDN. The address field of HDLC is 8 bytes and its control field is 8 bits, which is used to implement all kinds of control information of HDLC protocol and to mark whether they are data. VRP supportsthe HDLC protocol encapsulation and can interconnect with HDLC protocol of other popular devices.

6.1 Configuring HDLC

6.1.1 HDLC Configuration Task List

HDLC protocol can be configured with two commands:

l Encapsulate interface with HDLC protocol

l Set keepalive time delay

6.1.2 Encapsulating Interface with HDLC Protocol

In interface configuration mode, perform the following task to encapsulate the interfacewith HDLC protocol.

Table LLC-6-1 Configure interface with HDLC protocol

Operation Command

Encapsulate interface with HDLC protocol encapsulation hdl c

By default, the link layer protocol encapsulated on the interface is PPP.

Things should be noted:

Only when the interface operates in the synchronous mode, can it be encapsulatedwith HDLC.

When the interface is encapsulated with SLIP, its physical property cannot be changedto synchronous mode. At this time, you should first change the link layer encapsulationof the interface to PPP, and then you may change the interface property to synchronousmode.

After the interface is encapsulated with HDLC, the upper layer can still support IP andIPX.




Chapter 6Configuring HDLC

6.1.3 Setting Keepalive Time Delay

The keepalive parameter of HDLC protocol is used to set the polling interval of status

polling timer. keepalive of the equipment at both ends should be set to the same value.Perform the following task to set the parameter keepalive.

Table LLC-6-2 Set parameter keepalive

Operation Command

Set keepalive, with value range 0~32767 and in the unit of second;the default value is 10 seconds

keepalive value

Set keepalive to 0, i.e. to disable the link detection function no keepalive

By default, the delay of keepalive is 10 seconds.

Note the following point: the delay of keepalive set for the devices of the two ends mustbe the same.

6.2 Monitoring and Maintenance of HDLC

In privileged mode, perform the following task to monitor the current status of HDLC inreal time and carry out maintenance efficiently.

Table LLC-6-3 Monitoring and Maintenance of HDLC

Operation Command

Enable all the information debugging of HDLC protocol debug hdlc all [ interface type number ]

Enable HDLC event debugging debug hdlc event [ interface type number ]Enable HDLC packet debugging debug hdlc packet [ interface type number ]

03llc(link layer protocol configuration guide)

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