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Cisco VTP: VLAN Trunking Protocol/H2>VLAN Trunking Protocol (VTP) is a Cisco Layer 2 messaging protocol that manages the addition, deletion, and renaming of VLANs on a network-wide basis. Virtual Local Area Network (VLAN) Trunk Protocol (VTP) reduces administration in a switched network. When you configure a new VLAN on one VTP server, the VLAN is distributed through all switches in the domain. This reduces the need to configure the same VLAN everywhere. VTP is a Cisco-proprietary protocol that is available on most of the Cisco Catalyst Family products. VTP ensures that all switches in the VTP domain are aware of all VLANs. There are occasions, however, when VTP can create unnecessary traffic. All unknown unicasts and broadcasts in a VLAN are flooded over the entire VLAN. All switches in the network receive all broadcasts, even in situations where few users are connected in that VLAN. VTP pruning is a feature used to eliminate (or prune) this unnecessary traffic. By default, all Cisco Catalyst switches are configured to be VTP servers. This is suitable for small-scale networks where the size of the VLAN information is small and easily stored in all switches (in NVRAM). In a large network, a judgment call must be made at some point when the NVRAM storage needed is wasted, because it is duplicated on every switch. At this point, the network administrator should choose a few well-equipped switches and keep them as VTP servers. Everything else participating in VTP can be turned into a client. The number of VTP servers should be chosen so as to provide the degree of redundancy desired in the network. Modes of Operation
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ConfigurationTo configure an IOS based switch to be a VTP server, issue the following commands: SwitchA# vlan database SwitchA(vlan)# vtp domain vtpdom SwitchA(vlan)# vtp server SwitchA(vlan)# exit These commands configure the switch to be a VTP server in the VTP domain vtpdom. The changes are saved and the revision number is incremented when the exit command is issued. To configure a VTP client, run the following commands: SwitchB# vlan database SwitchB(vlan)# vtp domain vtpdom SwitchB(vlan)# vtp client SwitchB(vlan)# exit To disable VTP, set the vtp mode to transparent as such: SwitchC# vlan database SwitchC(vlan)# vtp transparent SwitchC(vlan)# exit To monitor the VTP operation and status, use either: SwitchA# show vtp status SwitchA# show vtp counters Note: I will populate this section later on with better examples from a running network as I finish revamping my network at my job. This page was created in 0.17606 seconds Comments and Questions
Last modified: October 03 2004. |