Cisco CCNA Certification – Cisco VTP VLAN Trunking Protocol

(VTP) is a Cisco Layer 2 messaging protocol that manages the addition, deletion, and renaming of VLANs on a network-wide foundation. Digital Native AreaNetwork (VLAN) Trunk Protocol (VTP) reduces administration in a switched community. If you configure a brand new VLAN on one VTP server, the VLAN is distributed via all switches within the area. This reduces the necessity to configure the identical VLAN in all places. VTP is a Cisco-proprietary protocol that’s obtainable on a lot of the Cisco Catalyst Household merchandise. VTP ensures that each one switches within the VTP area are conscious of all VLANs. There are events, nonetheless, when VTP can create pointless visitors. All unknown unicasts and broadcasts in a VLAN are flooded over all the VLAN. All switches within the community obtain all broadcasts, even in conditions the place few customers are related in that VLAN. VTP pruning is a function used to get rid of (or prune) this pointless visitors. By default, all Cisco Catalyst switches are configured to be VTP servers. That is appropriate for small-scale networks the place the dimensions of the VLAN data is small and simply saved in all switches (in NVRAM). In a big community, a judgment name have to be made in some unspecified time in the future when the NVRAM storage wanted is wasted, as a result of it’s duplicated on each change. At this level, the community administrator ought to select just a few well-equipped switches and maintain them as VTP servers. All the pieces else collaborating in VTP might be become a shopper. The variety of VTP servers needs to be chosen in order to supply the diploma of redundancy desired within the community.

Modes of OperationServer

In VTP server mode, you may create, modify, and delete VLANs and specify different configuration parameters (comparable to VTP model and VTP pruning) for all the VTP area. VTP servers promote their VLAN configuration to different switches in the identical VTP area and synchronize their VLAN configuration with different switches based mostly on commercials obtained over trunk hyperlinks. VTP server is the default mode.


VTP clear switches don’t take part in VTP. A VTP clear change doesn’t promote its VLAN configuration and doesn’t synchronize its VLAN configuration based mostly on obtained commercials. Nevertheless, in VTP model 2, clear switches do ahead VTP commercials that they obtain out their trunk ports.


VTP purchasers behave the identical approach as VTP servers, however you can not create, change, or delete VLANs on a VTP shopper.

Commercials Abstract Commercials

When the change receives a abstract commercial packet, it compares the VTP domainname to its personal VTP area identify. If the identify is totally different, the change merely ignores the packet. If the identify is similar, the change then compares the configuration revision to its personal revision. If its personal configuration revision is increased or equal, the packet is ignored. Whether it is decrease, an commercial request is distributed.

Subset Commercials

If you add, delete, or change a VLAN in a change, the server change the place the modifications have been made increments the configuration revision and points a abstract commercial, adopted by one or a number of subset commercials. A subset commercial incorporates an inventory of VLAN data. If there are a number of VLANS, multiple subset commercial could also be required with a view to promote all of them.

Commercial Requests

A change wants a VTP commercial request within the following conditions:

The change has been reset. The VTP area identify has been modified. The change has obtained a VTP abstract commercial with a better configuration revision than its personal. Upon receipt of an commercial request, a VTP system sends a abstract commercial, adopted by a number of subset commercials.

Configuration To configure an IOS based mostly change to be a VTP server, problem the next instructions: SwitchA# vlan database

SwitchA(vlan)# vtp area CiscoKits

SwitchA(vlan)# vtp server

SwitchA(vlan)# exit

These instructions configure the change to be a VTP server within the VTP area CiscoKits. The modifications are saved and the revision quantity is incremented when the exit command is issued. To configure a VTP shopper, run the next instructions:

SwitchB# vlan database

SwitchB(vlan)# vtp area CiscoKits

SwitchB(vlan)# vtp shopper

SwitchB(vlan)# exit

To disable VTP, set the vtp mode to clear as such:

SwitchC# vlan database

SwitchC(vlan)# vtp clear

SwitchC(vlan)# exit

To observe the VTP operation and standing, use both:

SwitchA# present vtp standing

SwitchA# present vtp counters.

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