LAN Switching and Wireless

CH4: VLAN TRUNKING PROTOCOL (VTP)

Abdelkhalik Mosa

If you found any mistake’s’ on these slides or if

you have any other questions or comments,

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Thanks, Abdelkhalik Elsaid Mosa

Suez Canal University Faculty of Computers and Informatics - Ismailia - Egypt

Note !

What is VTP

• VLAN Trunking Protocol (VTP) is a Cisco proprietary protocol that allows a network manager to configure a switch so that it will propagate VLAN configurations to other switches in the network.

What is VTP

• VTP maintains VLAN configuration consistency by managing the addition, deletion, and renaming of VLANs across multiple Cisco switches in a network.

VTP advertisements will not be exchanged if the trunk between the switches is inactive.

VTP Components: VTP Domain

• VTP Domain: Consists of one or more interconnected switches. All switches in a domain share VLAN configuration details using VTP

advertisements. A router or Layer 3 switch defines the boundary of each domain.

VTP Components: VTP Advertisements

• VTP Advertisements: VTP uses a hierarchy of advertisements to distribute and synchronize VLAN configurations across the network.

VTP Components: VTP Modes

• VTP Modes: A switch can be configured in one of three modes: server, client, or transparent.

VTP Components: VTP Modes

• VTP Server: advertises the VTP domain VLAN information to other VTP-enabled switches in the same VTP domain. VTP servers store the VLAN information for the entire domain in NVRAM. The server is where VLANs can be created, deleted, or renamed for the

domain.

• VTP Client: functions the same way as VTP servers, but you cannot create, change, or delete VLANs on a VTP client. A VTP client only stores the VLAN information for the entire domain while

the switch is on, a switch reset deletes the VLAN information.

• VTP Transparent: forwards VTP advertisements to VTP clients and VTP servers. Transparent switches do not participate in VTP. VLANs that are created,

renamed, or deleted on transparent switches are local to that switch only.

VTP Components: VTP Pruning

• VTP Pruning: increases network available bandwidth by restricting flooded traffic to those trunk links that the traffic must use to reach the destination devices.

Relax and Refresh

Default VTP Configuration

S# show vtp status

VTP Domains

• VTP allows you to separate your network into smaller management domains to help reduce VLAN management.

• VTP domains limit the extent to which configuration changes are propagated in the network if an error occurs.

• A switch can be a member of only one VTP domain at a time. • Until the VTP domain name is specified you cannot create or modify VLANs on

a VTP server, and VLAN information is not propagated over the network.

VTP Advertisements

• VTP advertisements (or messages) distribute VTP domain name and VLAN configuration changes to VTP-enabled switches.

• VTP Header generally contains: Domain name, Domain name length, version, Message type, and revision number

VTP Message Contents

VTP Revision Number

• The configuration revision number is a 32-bit number that indicates the level of revision for a VTP frame. The default configuration number for a switch is zero. Each time a VLAN is added or removed, the configuration revision number

is incremented. Changes in VTP domain name, resets the revision number to zero.

Types of VTP advertisements: Summary Advertisement

• The summary advertisement contains the VTP domain name, the current revision number, and other VTP configuration details.

Types of VTP advertisements: Subset Advertisement

• A subset advertisement contains VLAN information.

Types of VTP advertisements: Request Advertisement

• When a request advertisement is sent to a VTP server in the same VTP domain, the VTP server responds by sending a summary advertisement and then a subset advertisement.

Summary details

• Version: Displays the VTP version, on Catalyst 2960 v1 or v2.• Code: Identifies the type of advertisement ‘0X01’.• Followers: Identifies that this packet is followed by a subset advertisement.• MgmtD Len: The length of domain name.• Management Domain Name: The domain name.• Configuration Rev. num.: The Rev. Num. of the VTP server sending the msg.• Updater Identity: the IP add. Of the switch that is the last to have incremented the

configuration revision.• Update Timestamp: Date & time of the last increment of the configuration revision.• MD5 Digest: carries the VTP Password.

Subset details

• Version: Displays the VTP version, on Catalyst 2960 v1 or v2.• Code: Identifies the type of advertisement, “0x02”.• Seq-Number: The sequence of the packet in the stream of packets that follow a

summary advertisement, starts with 1.• MgmtD Len: The length of domain name.• Management Domain Name: The domain name.• Configuration Rev. num.: The Rev. Num. of the VTP server sending the msg.

Request details

• Version: Displays the VTP version, on Catalyst 2960 v1 or v2.• Code: Identifies the type of advertisement, “0x03”.• Rsvd: A reserved field.• MgmtD Len: The length of domain name.• Management Domain Name: The domain name.• Start Value: is used when there are several subset advertisements.

VTP Modes

• Cannot create, change, or delete VLANs

• Forwards advertisements after taking a copy.

• Not saved in NVRAM

• Creates VLANs• Modifies VLANs• Deletes VLANs• Sends and forwards advertisements• Saved in NVRAM• Default mode

• Creates local VLANs only• Modifies local VLANs only • Deletes local VLANs only• Doesn’t advertise local

configuration.• Sends and forwards

advertisements without being affected

• Saved in NVRAM

VTP in Action

VTP in Action

VTP in Action

VTP in Action

VTP in Action

VTP in Action

VTP in Action

VTP in Action

VTP in Action

VTP in Action

VTP Pruning

• VTP pruning prevents unnecessary flooding of broadcast information from one VLAN across all trunks in a VTP domain.

VTP Configuration

• scu_fci# show vtp status• scu_fci# conf t• scu_fci(config)# vtp domain <domain-name> • scu_fci(config)# vtp mode [ server | client | transparent ]• scu_fci(config)# vtp version <I or 2>• scu_fci(config)# vtp password <password>• scu_fci# show vtp counters

Troubleshooting VTP Connections

Troubleshooting VTP Connections: Incompatible VTP Versions

Troubleshooting VTP Connections: Incorrect VTP Domain Name

Troubleshooting VTP Connections: Switches Set to VTP Client Mode

Troubleshooting VTP Connections: Incorrect Revision Number

Managing VLANs on a VTP Server

Thank You..