mstp interoperability between sr4134 and ers8600

Secure Router 4134

Ethernet Routing Switch 8600

Engineering

Multiple Spanning Tree Protocol (MSTP) Interoperability between Secure Router 4134 and Ethernet Routing Switch 8600 Technical Configuration Guide

Core Systems Engineering Document Date: November 2010 Document Number: NN48500-565 Document Version: 1.1

Multiple Spanning Tree Protocol (MSTP) Interoperability between Secure Router 4134 and Ethernet Routing Switch 8600

Technical Configuration Guide

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Abstract This document describes the Multiple Spanning Tree Protocol (MSTP) and interoperability between the SR 4134 (software release 10.0) and ERS 8600 (software release 4.1.5.4).



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Table of Contents

1. Overview: Spanning Tree Protocol ................................................................................................... 5

1.1 Spanning Tree Protocol Details .................................................................................................... 6

2. Rapid Spanning Tree Protocol .......................................................................................................... 7

2.1 Overview ....................................................................................................................................... 7 2.2 Edge Ports ..................................................................................................................................... 7 2.3 Root Bridge Election/Change ........................................................................................................ 7 2.4 Topology Change .......................................................................................................................... 9

3. Multiple Spanning Tree Protocol .................................................................................................... 10

4. Configuration Example .................................................................................................................... 11

4.1 ERS 8606 Configuration ............................................................................................................. 12 4.2 SR 4134 Configuration ................................................................................................................ 12 4.3 Verification ................................................................................................................................... 13 4.4 Default Configuration .................................................................................................................. 16

5. Conclusion ........................................................................................................................................ 21

6. Customer service ............................................................................................................................. 22

6.1 Getting technical documentation ................................................................................................. 22 6.2 Getting product training ............................................................................................................... 22 6.3 Getting help from a distributor or reseller .................................................................................... 22 6.4 Getting technical support from the Avaya Web site .................................................................... 22

Appendix A - ERS 8606 Configuration (sw release 4.1.5.4) ................................................................. 23

Appendix B - SR 4134A Configuration (sw version 10.0, GA release) ................................................ 25

Appendix C - SR 4134B Configuration (sw version 10.0, GA release) ................................................ 27

Appendix D - Definitions .......................................................................................................................... 29

Appendix E - A poem by Radia Perlman ................................................................................................. 30



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1. Overview: Spanning Tree Protocol

The Spanning Tree Protocol (STP - IEEE Standard 802.1D) was originally developed to allow a switched network to be built with redundant paths while preventing loops.

Difficulties that a loop can cause include forwarding table corruption and broadcast storms. With a loop, the same MAC address will be seen on multiple ports which can cause the switch forwarding algorithm to fail. When a broadcast packet is transmitted, each switch floods that packet out all ports. When that packet traverses the loop and is received back at the original switch, it is flooded out again, resulting in an endless loop, high network utilization and/or saturating system CPUs.

Figure 1 - Spanning Tree Example – normal operation

Through the STP, one port of a redundant link is blocked (see figure 1), preventing data traffic from traversing the network in a loop. If something happened to break one of the active links, the blocked port would automatically resume traffic flow, restoring connectivity (see figure 2).

Figure 2 - Spanning Tree Example – Link Failure, Traffic Restored



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1.1 Spanning Tree Protocol Details

The heart of the Spanning Tree Protocol (STP) is election of a root bridge. The root bridge is determined based on bridge ID. The bridge ID is 8 bytes. The most significant byte is the bridge priority (set by the administrator), the next 3 bytes are used by MSTP and the final 6-bytes are the system MAC address. The bridge with the lowest numerical ID becomes root.

Information about bridge (note: for purposes of this document the terms bridge and switch are synonymous) configuration and interconnections, including bridge priority and path cost, is shared between the switches using packets known as Bridge Protocol Data Units (BPDUs).

In STP, there are two types of BPDUs, „configuration‟ and „topology change‟. Configuration BPDUs originate at the root bridge and contain root-bridge ID and path-cost information. Topology change BPDUs are used by one bridge to notify the root bridge (and, in turn, all other bridges in the network) that one or more links have changed.

Initially, each bridge in a network assumes it is the root bridge and sends its own identifying information in a Configuration BPDU. When a bridge receives a Configuration BPDU from another bridge with a better preference (lesser Bridge ID), it stops transmitting its own BPDU and starts forwarding the BPDU from this better priority bridge.

The root port for a switch is the port it uses to transmit data in the direction of the root bridge. If a switch receives a Configuration BPDU from the root bridge on more than one port, the port that has the lowest path cost back to the root bridge becomes the root port for that switch. The root port is kept active and any other port with a path to the root bridge is placed into a blocking state. Blocked ports continue to receive and process BPDUs. Data traffic received on blocked ports is discarded and neither data traffic nor BPDUs are transmitted out a blocked port.

Eventually, all bridges share the same root bridge identifying information and have identified one of their ports as a root port. This process is known as root-bridge election.

The root bridge is responsible for originating configuration BPDUs. The BPDU is transmitted out all active interfaces every “Hello Time” interval (default value is 2 seconds). Each switch in the network receives this packet on its root (and possibly other) port and forwards it out all its active ports, adjusting cost information appropriately.

Each bridge listens for BPDUs from other bridges on a LAN segment. The port on the bridge with the lowest cost back to the root bridge is the “designated” port for that LAN segment. The designated port is used for forwarding any traffic from that LAN segment back toward the root bridge. If only one switch is connected to the LAN, its connected port is the designated port for the LAN.

If the root port fails to receive a BPDU for some period of time, the root information will time out and the switch will go through the election process again to determine which, if any, of its other ports will become the root port. If no other port on the bridge has a path to the root bridge, this bridge will attempt to become the root and may be isolated from the rest of the network.

When a bridge detects a change in topology, it sends a Topology Change BPDU to the Root Bridge. The Root Bridge in turn sets the Topology Change (TC) flag in its configuration BPDU to notify all bridges in the network (including the bridge that first detected the topology change) of the topology change. When a bridge receives a TC notification, it changes its MAC aging timer from long to short (default 15 seconds) to age out stations that may now be connected through another port.

In order to prevent temporary loops when a port first becomes active, the port transitions through a series of states. A device is connected to this port. After the port goes through its initialization and any speed/duplex negotiations, it is placed in a blocking state. After some period of time, it will transition to the listening state (processes BPDUs and management traffic only, discards all other traffic). After another period of time, it starts learning station addresses (learning state) and, after another period of



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time, it finally starts forwarding traffic. It can take 30 seconds to transition through these states and start forwarding traffic.

2. Rapid Spanning Tree Protocol

In part, due to the lengthy transition and convergence times of STP, in 1998, the IEEE introduced some changes to the STP, via the 802.1w draft standard. This new standard was known as Rapid Spanning Tree Protocol (RSTP). The standard was approved and incorporated as a replacement to STP in the IEEE 802.1D – 2004 standard.

2.1 Overview

RSTP works similarly to STP. Both reduce a bridged network to a single tree topology by blocking certain ports and computation of the spanning tree is identical in either case. However, there are a number of changes in the protocol that significantly speed up convergence when there is a change in topology. For example, using the original STP, a typical reconvergence can take anywhere from 30 to 50 seconds. RSTP reduces delays such that, in a well designed network, reconvergence can take less than a second. Time for reconvergence is dependent on the failure mode. If a single link fails, recovery will be very fast. If the root bridge fails, recovery will take longer.

RSTP also introduces the concept of „edge ports‟, which speeds up how quickly an end station can communicate with the network.

2.2 Edge Ports

When using STP, a station attaching to the network is isolated for about 30 seconds while STP insures this new connection will not cause a loop.

With RSTP, an administrator can designate ports that connect to end-stations (devices that cannot cause loops) as „edge ports‟ (i.e. FastStart). When an edge port becomes active, it goes immediately into a forwarding state, bypassing the normal state transitions that delay forwarding on a non-edge port. Edge ports continue to listen for BPDUs and will automatically switch the port to a non-edge port, if a BPDU is received.

Note: some vendors implemented a similar feature in STP, before RSTP became a standard.

2.3 Root Bridge Election/Change

Unlike in STP, an RSTP bridge will respond to BPDUs coming from the direction of the root bridge. When a bridge determines that a BPDU received on a port has superior root access, it will respond back with an “acknowledgement” that this is now the designated port and will set its other ports to discarding. The bridge that sent out the superior BPDU will receive the acknowledgement and rapidly transition its port to a forwarding state, bypassing the normal listening/learning states.

While not actively using them, an RSTP switch does keep track of ports that provide an alternate path to the root bridge.



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Figure 3 - RSTP Switches Normal Operation

Each RSTP switch expects to receive a BPDU within 3 Hello times (default Hello time is 2 seconds). If a link fails (See figure 4), switch B will not receive a BPDU on its root port within the allotted time and will declare itself the root bridge and start advertising as root to its neighbor (switch D). Switch D receives this new root bridge proposal and will compare it with its known path information to the original root bridge. Switch D will recognize Switch B‟s proposal as being inferior, activate its alternate port and designate its alternate port as its new root port. Switch D will also advertise this new path back to Switch B. Switch B will accept this data, do a quick handshake with Switch D, designate its port connecting to Switch D as its new root port and immediately start forwarding traffic out this port, resulting in a much quicker convergence than would happen in standard STP.

Figure 4 – Traffic Recovery after Link Failure



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2.4 Topology Change

In normal operation, an RSTP switch originates its own BPDUs (vs. waiting for and forwarding a BPDU from the root bridge). When a topology change is detected, the switch that detects the change will set the TC bit in its BPDU. In addition, it will immediately purge old MAC entries from its forwarding table. Each switch that receives a BPDU, with TC set, will forward that BPDU on and also purge its forwarding entries immediately. No longer requiring a Topology Change Notification to reach the root bridge and be re-propagated out to the network speeds up reconvergence.



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3. Multiple Spanning Tree Protocol

With STP and RSTP, when there is a loop in the network, one of the links is disabled to remove the loop. This limits broadcast storms, but also prevents taking full advantage of all available bandwidth by limiting all traffic to a single path.

In 2002, Multiple Spanning Tree Protocol (MSTP) was proposed as an enhancement to RSTP in the IEEE 802.1s draft. This proposal was incorporated into the 802.1Q-2003 standard.

MSTP enhances RSTP by allowing the administrator to designate separate virtual spanning tree groups (STGs) for different (groups of) VLANs. Using MSTP, links can be blocked for one or more STGs while passing traffic for other STGs, better utilizing all available bandwidth.

MSTP introduces a number of new concepts:

Multiple Spanning Tree Instance (MSTI) - is a single instance of a spanning tree in an MST region. An MSTI can be used for forwarding traffic for one or more VLANs. The SR 4134 supports MSTI numbers 1 - 15. The ERS 8600 supports MSTI numbers 1 - 63. Each MST instance will have its own root bridge. A bridge may be root for more than one MSTI.

MST Region - is a group of bridges that have identical definitions for Region Name, Region Version, VLANs and VLAN to MSTI mappings. I.e. regardless if they are used on a particular switch, all VLANs in the region must be defined on all switches and must be mapped to the same MSTI number. Each region will have a single regional root bridge. The regional root bridge may also be an MSTI root bridge.

Common Internal Spanning Tree (CIST) – is used for sharing topology information among bridges within a region. All topology information is transferred between switches using the CIST. No topology information is transferred through an MSTI.

Common Spanning Tree (CST) – is used for passing topology information among different MST regions and non-MSTP switches.

Topology information for all MSTIs is encoded in a single BPDU format that is transmitted using the CIST. The additional MSTP configuration information is encoded after the standard RSTP BPDU information. This reduces the bandwidth overhead while maintaining backward compatibility with RSTP and STP switches.

This format allows a switch outside of the MST region to view the region as a single switch, regardless of the number of switches in the MST region. Ports at the edge of an MST region connected to either a RSTP or STP bridge or an endpoint are known as boundary ports. As in RSTP, these ports can be configured as edge ports to facilitate rapid changes to the forwarding state when connected to endpoints.



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4. Configuration Example

The following diagram illustrates a testbed that was built to test and verify interoperability. The following sections document the configuration of the ERS 8600 and SR 4134A. The configuration of SR 4134B will be similar to the SR 4134A and is not documented, except as necessary to demonstrate a point. Complete configuration information for the ERS 8600 is included in Appendix A.

In order for the switches to form a region, all switches must be configured with the same region name, version number and VLAN to MSTI mapping. The following information is used for this interoperability test:

Region Name MSTPLAB

Version 1

VLAN Mapping

o VLAN 1104 mapped to MSTI 3



VLAN 1186 is only used on the ERS 8600, so no ports will be mapped to it on the SR 4134s however; it needs to be defined on the SR 4134s to insure the MSTI to VLAN mapping is identical across all switches. All links between the switches are 802.1Q tagged and carrying VLANs 1104 and 1106.

Figure 5 - MSTP Example Network



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4.1 ERS 8606 Configuration

The CLI will be used in this example. JDM could also be used to configure the ERS 8600.

By default, an ERS 8600 will be in Avaya STP mode. To configure MSTP, the boot-config flag “spanning-tree-mode” must be set to “mstp”, the configuration saved and the box rebooted.

Note: Changing the ST mode removes any configured STG and/or VLAN information. It is recommended that configurations be backed-up prior to changing ST modes.

While an ERS 8606 was used for this testing, other Avaya (or competitor) switches that support MSTP could also be used. The configuration of other Avaya switches will be very similar.

To set the region name and revision number, enter the following commands:

ERS-8606:6# config mstp region name MSTPLAB

ERS-8606:6# config mstp region revision 1

Then, define the VLANs and associate them to the MSTIs. On an ERS 8600, the association of VLAN number to MSTI is made when the VLAN is created. For purposes of this paper, the configuration of VLAN 1104 will be fully documented. Complete configuration of other VLANs will be similar. This command creates port-based vlan 1104, and associates it with MSTI 3.

ERS-8606:6# config vlan 1104 create byport-mstprstp 3

There are other configuration parameters available, including name, color etc. Configuration of these parameters is implementation specific and is not addressed in this paper.

After the VLANs have been created, appropriate ports, IP address and other parameters must be associated with the VLAN as required by the network design.

ERS-8606:6# vlan 1104 ports add 3/2,3/14

ERS-8606:6# vlan 1104 ip create 10.104.6.1/255.255.255.0

4.2 SR 4134 Configuration

Configuration of the VLANs on the SR 4134 is a bit different than the ERS 8600. The VLANs need to be defined and then associated with the MSTI. Currently there is no GUI configuration manager for the SR 4134. Using the CLI:

Define the VLANs (note: valid values for VLAN ID on the SR 4134 are 1 through 4000):

vlan database

vlan 1104

vlan 1106

vlan 1186

exit database

Set the region name (the name you specify for the MSTP region) and revision (valid values are 0 to 255 – default is 0). Then associate the VLANs with MSTIs:

bridge

mstp

revision 1

region MSTPLAB

instance 3

vlan 1104

exit instance



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instance 5

vlan 1106

exit instance

instance 10

vlan 1186

exit instance

exit mstp

exit bridge

Note: On the SR 4134, you can explicitly assign a priority to the bridge. This is configured under the bridge configuration context using "priority <value>" command. The lower the priority, the greater the chance that the bridge becomes root for the CST. The default value is 32768 (or hex 0x8000). Valid values are 0 to 61440 and are increments of 4096.

Associate the IP address with the VLAN:

interface vlan vlan1104

ip address 10.104.6.3 255.255.255.0

exit vlan


ip address 10.106.6.3 255.255.255.0

exit vlan

Define the trunk ports to the VLANs;

interface ethernet 7/1

switchport

switchport mode trunk

switchport trunk allowed vlan 1,1104,1106

exit ethernet


switchport



exit ethernet

That completes the MSTP configuration for the ERS 8606 and SR-4134A. SR-4134B will be configured similarly. Complete configurations for the SR 4134s are in Appendix B and C.

4.3 Verification

After configuration, we want to insure that all switches are in the same region and are sharing topology information correctly. To verify, check each switch and insure that the regional root is identical.

If the switches are not in the same region, verify the region name, revision number and VLAN to MSTI mapping. All of this information is displayed on the ERS 8606 and SR 4134, as follows:

From the ERS 8600, issue the command:

ERS-8606:6# show mstp status

=================================================================

MSTP Status

=================================================================------

-----------------------------------------------------------Bridge

Address : 00:16:60:11:70:01

Cist Root : 80:00:00:16:60:11:70:01



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Cist Regional Root : 80:00:00:16:60:11:70:01

Cist Root Port : cpp

Cist Root Cost : 0

Cist Regional Root Cost : 0

Cist Instance Vlan Mapped : 1-1024

Cist Instance Vlan Mapped2k : 1025-1103,1105,1107-1185,1187-2048

Cist Instance Vlan Mapped3k : 2049-3072

Cist Instance Vlan Mapped4k : 3073-4094

Cist Max Age : 20 seconds

Cist Forward Delay : 15 seconds

ERS-8606:6#

This shows the bridge address for the ERS 8606 and the current CIST Root and regional Root bridge IDs.

ERS-8606:6# show mstp config

=================================================================

MSTP Configurations

=================================================================

Mstp Module Status : Enabled

Number of Msti Supported : 64

Cist Bridge priority : 32768 (0x8000)

Stp Version : Mstp Mode

Cist Bridge Max Age : 20 seconds

Cist Bridge Forward Delay : 15 seconds

Tx Hold Count : 3

PathCost Default Type : 32-bit

Max Hop Count : 2000

Msti Config Id Selector : 0

Msti Region Name : MSTPLAB

Msti Region Version : 1

Msti Config Digest :

72:01:b9:09:3e:21:68:93:b9:69:f9:c4:aa:89:02:f8

This shows the MSTI region name and version number. Note the MSTI Config Id Selector. This should be set to 0 and indicates that Region Name and Version are specified according to the standard.

VLAN to MSTI mapping is displayed per instance. Issue the following command for each configured instance (instance 3 is used as an example):

ERS-8606:6# show mstp instance 3

=================================================================

MSTP Instance Status

=================================================================

Instance Id : 3

Msti Bridge Regional Root : 80:00:00:16:60:11:70:01

Msti Bridge Priority : 32768 (0x8000)

Msti Root Cost : 0

Msti Root Port : cpp

Msti Instance Vlan Mapped :

Msti Instance Vlan Mapped2k : 1104

Msti Instance Vlan Mapped3k :

Msti Instance Vlan Mapped4k :



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Note that the only VLAN mapped to instance 3 is 1104, which matches the SR 4134 mappings.

On the SR 4134, issue the following command, this will show the region name, revision number and MSTI to VLAN mappings:

SR4134-A# show spanning-tree detail

Bridge Status : up

Spanning Tree Enabled

CIST Information :

RootId 8000001660117001

Reg RootId 8000001660117001 (Note: Same as ERS-8606)

BridgeId 8000001bba620301

Root Port ethernet7/1

Root PathCost 0

Priority 32768

Fwd Delay 15

Hello Time 2

Max-Age 20

Max-Hops 20

Region MSTPLAB (Note: Same as ERS-8606)

Revision 1 (Note: Same as ERS-8606)

Port Information :

Port Name Instance Priority Role State

PortFast/Filter/Guard

ethernet7/5 CIST 128 Rootport Forwarding Disable

ethernet7/1 CIST 128 Designated Forwarding Disable

Instance Information :

Instance Id 3

Priority 32768

Ports List :

Interface Priority Path Cost role state

ethernet7/5 128 200000 Alternate Discarding

ethernet7/1 128 200000 Rootport Forwarding

Vlan List :

1104

Instance Id 5

Priority 32768

Ports List :




Vlan List :

1106

Instance Id 10

Priority 32768

Ports List :

Port List is NULL



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Vlan List :

1186

Note that the Cist Regional Root on the ERS 8606 matches the Reg RootId on the SR 4134, indicating that they are in the same region.

4.4 Default Configuration

After initial configuration, the network will be as displayed in the following diagram. For the test network, the ERS 8606 becomes the regional root and root bridge for all MSTIs.

Figure 6 - MSTP Example Network Port Status

Following convergence, since the ERS-8606 is the root bridge, all of its ports are designated. The port from each SR 4134 that is connected to the ERS 8606 is the root port for that switch. Port 6/3 on SR 4134-B becomes the designated port for the network between the SR 4134s. Under the default configuration, no traffic will traverse the link between the SR 4134s.

Assume there are a server and end-station attached to each SR 4134. Station 3 and Server 3 are attached to VLAN 1104 (MSTI-3). Station 5 and Server 5 are attached to VLAN 1106 (MSTI-5).

With the default configuration, in order for Station 3 to communicate with Server 3 or Station 5 to communicate with Server 5, the traffic must traverse the 8600, not utilizing the direct path. If both applications require high bandwidth, there could be network contention.

There are a couple of ways to configure the network to utilize the path between the SR 4134s. The simplest would be to change the bridge priority on one of the SR 4134s to make it the root bridge. However, the link from the other SR 4134 to the ERS8606 would not be utilized at all.



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To allow all links to be utilized, we can adjust the bridge priority per instance, so that the link between the SR 4134s is being used for one MSTI, while the path through the ERS 8606 is used for the other MSTI. Adjust the bridge priority for MSTI 3 on SR 4134-A to be 4096 (any value lower than the default 32768 would work):

SR4134-A/configure# bridge

SR4134-A/configure/bridge# mstp

SR4134-A/configure/bridge/mstp# instance 3

SR4134-A/configure/bridge/mstp/instance 3# priority 4096

The network will now look like:

Figure 7 - MSTP Example Network Modified Port Status

Verify the port roles for the ERS 8606 and SR 4134-A:

SR4134-A# show spanning-tree detail

Bridge Status : up

Spanning Tree Enabled

CIST Information :

RootId 8000001660117001

Reg RootId 8000001660117001

BridgeId 8000001bba620301

Root Port ethernet7/1

Root PathCost 0

Priority 32768

Fwd Delay 15

Hello Time 2



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Max-Age 20

Max-Hops 20

Region MSTPLAB

Revision 1

Port Information :

Port Name Instance Priority Role State

PortFast/Filter/Guard

ethernet7/5 CIST 128 Alternate Discarding Disable

ethernet7/1 CIST 128 Rootport Forwarding Disable

Instance Information :

Instance Id 3

Priority 4096

Ports List :


ethernet7/5 128 200000 Designated Forwarding

ethernet7/1 128 200000 Designated Forwarding

Vlan List :

1104

Instance Id 5

Priority 32768

Ports List :




Vlan List :

1106

It is also helpful to look at the instance information to see the root bridge for instance 3:

SR4134-A# show spanning-tree mstp instance 3

Instance Priority Root Root Id Designated Root

PathCost Bridge Id Port

3 4096 0 1003001bba620301 1003001bba620301

Similar information can be displayed on the ERS 8606.

ERS-8606:6/show/ports/info/mstp# mstiinfo

=============================================================

MSTP Inst-Specific Per-Port Information

(Port Priority Vector)

=============================================================

Port Number : 3/1

Instance Id : 10

Msti Port PathCost : 20000

Msti Port Priority : 128 (0x80)

Msti Port Designated Root : 80:00:00:16:60:11:70:01

Msti Port Designated Cost : 20000

Msti Port Designated Bridge : 80:00:00:16:60:11:70:01

Msti Port Designated Port : 80:c0



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(Note: The Designated root for MSTI 3 is now the SR4134A)

Port Number : 3/2

Instance Id : 3



Msti Port Designated Root : 10:00:00:1b:ba:62:03:01


Msti Port Designated Bridge : 10:00:00:1b:ba:62:03:01


Port Number : 3/2

Instance Id : 5







(Note: The Designated root for MSTI 3 is now the SR4134A)

Port Number : 3/14

Instance Id : 3



Msti Port Designated Root : 10:00:00:1b:ba:62:03:01



Msti Port Designated Port : 80:cd

Port Number : 3/14

Instance Id : 5






Msti Port Designated Port : 80:cd

There are some other commands that provide useful information:

ERS-8606:6/show/ports/info/mstp# ?

Current Context:

cistinfo [vlan <value>] [port <value>]

mstiinfo [vlan <value>] [port <value>]

ciststat [vlan <value>] [port <value>]

mstistat [vlan <value>] [port <value>]

cistrole [vlan <value>] [port <value>]

mstirole [vlan <value>] [port <value>]

The ERS 8606 is still the regional root bridge, however, the SR 4134-A is now the root bridge for Instance 3.



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Since SR 4134-A is the root for MSTI-3 (note: all its ports are designated ports for MSTI-3), traffic between Station 3 and Server 3 will traverse the network between the SR 4134s. MSTI-5 traffic will continue to traverse the ERS 8606, as before. Please note that traffic from SR 4134-B that is intended for the ERS 8606 must traverse through SR 4134-A and will not be forwarded over the direct link.

This will now utilize all links for traffic, while providing a failover capability, if one of the links should fail.

For testing purposes, a continuous ping was initiated between Station 3 and Server 3, the link between the SR 4134s was broken and the traffic monitored. When the link was severed, a single ping was lost (~1 to 2 seconds), before traffic flow was restored. When the link was reinserted, traffic flow was interrupted for approximately 2 ping times (~2 to 3 seconds) before traffic flow was restored.

The test was repeated between Station 5 and Server 5. Normal flow for MSTI 5 is through the 8600. Breaking the link between the SR 4134s did not interrupt traffic flow at all.



21 November 2010

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5. Conclusion

This is a very simplistic example. However, it demonstrates the concepts of MSTP and how MSTP can be configured to insure all available links are utilized.

The testing demonstrates the speed with which MSTP reconverges after a link failure or restore. Compare these times to the 30 seconds or more that normal STP would take to restore traffic flow.



22 November 2010

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6. Customer service

Visit the Avaya Web site to access the complete range of services and support that Avaya provides. Go to www.avaya.com or go to one of the pages listed in the following sections.

6.1 Getting technical documentation

To download and print selected technical publications and release notes directly from the Internet, go to www.avaya.com/support.

6.2 Getting product training

Ongoing product training is available. For more information or to register, you can access the Web site at www.avaya.com/support. From this Web site, you can locate the Training contacts link on the left-hand navigation pane.

6.3 Getting help from a distributor or reseller

If you purchased a service contract for your Avaya product from a distributor or authorized reseller, contact the technical support staff for that distributor or reseller for assistance.

6.4 Getting technical support from the Avaya Web site

The easiest and most effective way to get technical support for Avaya products is from the Avaya Technical Support Web site at www.avaya.com/support.

http://www.avaya.com/

http://www.avaya.com/support





23 November 2010

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Appendix A - ERS 8606 Configuration (sw release 4.1.5.4)

Unused sections of the configuration have been removed to simplify this display.

Boot Configuration (from boot.cfg):

# WED DEC 05 21:57:32 2007 UTC

# box type : 8k boot configuration file

#

flags ftpd true

flags savetostandby true

flags spanning-tree-mode mstp

flags sshd true

flags telnetd true

flags tftpd true

choice primary image-file "p80a4154.img"

net mgmt ip 192.168.168.170/255.255.255.0 cpu-slot 5

mezz-image image-name "p80m4154.img"

System Configuration (from config.cfg):

# TUE DEC 11 19:09:14 2007 UTC

# box type : ERS-8006

# software version : 4.1.5.4

# monitor version : 4.1.5.4

#

#

# Asic Info :

# SlotNum|Name |CardType |MdaType |Parts Description

#

# Slot 1 -- 0x00000001 0x00000000

# Slot 2 -- 0x00000001 0x00000000

# Slot 3 8648GTR 0x24220130 0x00000000 RSP=25 CLUE=0 F2I=4 F2E=3 FTMUX=17

CC=3 FOQ=267 DPC=184 BMC=776 PIM=3 MAC=2

# Slot 4 -- 0x00000001 0x00000000

# Slot 5 -- 0x00000001 0x00000000

# Slot 6 8692SF 0x200e0100 0x00000000 CPU: CPLD=19 MEZZ=4 SFM: OP=3

TMUX=2 SWIP=23 FAD=16 CF=28

#

#

# PORT CONFIGURATION - PHASE I

#

ethernet 3/2 perform-tagging enable

ethernet 3/14 perform-tagging enable

#



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# VLAN CONFIGURATION

#

vlan 1 ports remove 3/1-3/8,3/13,3/15-3/18 member portmember

vlan 1104 create byport-mstprstp 3 color 1

vlan 1104 ports remove 3/1,3/3-3/13,3/15-3/48 member portmember

vlan 1104 ports add 3/2,3/14 member portmember

vlan 1104 ip create 10.104.6.1/255.255.255.0 mac_offset 1

vlan 1106 create byport-mstprstp 5 color 1

vlan 1106 ports remove 3/1,3/3-3/13,3/15-3/48 member portmember

vlan 1106 ports add 3/2,3/14 member portmember


vlan 1186 create byport-mstprstp 10

vlan 1186 ports remove 3/2-3/48 member portmember

vlan 1186 ports add 3/1 member portmember


#

# MSTP CONFIGURATION

#

mstp region name MSTPLAB

mstp region revision 1

#

# PORT CONFIGURATION - PHASE II

#

ethernet 3/1 mstp cist forceportstate disable

ethernet 3/1 mstp msti 10 forceportstate disable

ethernet 3/2 default-vlan-id 1104

#

# IP ROUTE POLICY CONFIGURATION

#

ip static-route create 0.0.0.0/0.0.0.0 next-hop 47.17.186.1 cost 10

ip static-route create 47.17.199.232/255.255.255.248 next-hop 47.17.199.226

cost 10 preference 5



25 November 2010

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Appendix B - SR 4134A Configuration (sw version 10.0, GA release)

System Configuration (from system.cfg):

vlan database

vlan 1104

vlan 1106

vlan 1186 name VLAN1186

exit database

bridge

mstp

revision 1

region MSTPLAB

instance 3

priority 4096

vlan 1104

exit instance

instance 5

vlan 1106

exit instance

instance 10

vlan 1186

exit instance

exit mstp

exit bridge


switchport



spanning-tree

exit spanning-tree

gvrp

exit gvrp

ip igmp snooping

exit snooping

qos

module

exit module

exit qos

exit ethernet


switchport



spanning-tree

exit spanning-tree

gvrp

exit gvrp

ip igmp snooping



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exit snooping

qos

module

exit module

exit qos

exit ethernet


ip address 10.106.6.3 255.255.255.0

exit vlan


ip address 10.104.6.3 255.255.255.0

exit vlan

hostname SR4134-A



27 November 2010

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Appendix C - SR 4134B Configuration (sw version 10.0, GA release)

System Configuration (from system.cfg):

vlan database

vlan 1104

vlan 1106

vlan 1186 name VLAN1186

exit database

bridge

mstp

revision 1

region MSTPLAB

instance 3

vlan 1104

exit instance

instance 5

vlan 1106

exit instance

instance 10

vlan 1186

exit instance

exit mstp

exit bridge


switchport



spanning-tree

exit spanning-tree

gvrp

exit gvrp

ip igmp snooping

exit snooping

qos

module

exit module

exit qos

exit ethernet


speed 100 full_duplex

switchport



spanning-tree

exit spanning-tree

gvrp

exit gvrp

ip igmp snooping



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exit snooping

qos

module

exit module

exit qos

exit ethernet


ip address 10.104.6.2 255.255.255.0

exit vlan


ip address 10.106.6.2 255.255.255.0

exit vlan



29 November 2010

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Appendix D - Definitions BPDU – Bridge Protocol Data Unit - A message type used by bridges to exchange management and control information.

MAC – Media Access Control – The physical layer of a network interface.

STP Port states:

* Blocking - A port that would cause a switching loop (if it were transmitting data), no user data is sent or received but it may go into forwarding mode if the other links in use were to fail and the spanning tree algorithm determines the port may transition to the forwarding state. BPDU data is still received in blocking state.

* Listening - The switch processes BPDUs (i.e. sends and receives BPDUs) and awaits possible new information that would cause it to return to the blocking state.

* Learning - While the port does not yet forward frames (packets) it does learn source addresses from frames received and adds them to the filtering database (switching database). This port will send and receive BPDUs.

* Forwarding - A port receiving and sending data, normal operation. STP still monitors incoming BPDUs that would indicate it should return to the blocking state to prevent a loop. This port will send and receive BPDUs.

* Disabled - Not strictly part of STP, a network administrator can manually disable a port, which will stop any packet transmission. Any received packets are discarded.



30 November 2010

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Appendix E - A poem by Radia Perlman For those that may have forgotten the poem that first described Spanning Tree Protocol.

Algorhyme

I think that I shall never see

a graph more lovely than a tree.

A tree whose crucial property

is loop-free connectivity.

A tree that must be sure to span

so packet can reach every LAN.

First, the root must be selected.

By ID, it is elected.

Least-cost paths from root are traced.

In the tree, these paths are placed.

A mesh is made by folks like me,

then bridges find a spanning tree.

Radia Perlman

mstp interoperability between sr4134 and ers8600

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