VTP Modes Explained

My days in semester 3 of the Cisco Networking Academy are drawing to a middle, in just a few hours I will have to take a midterm skills final that will test my knowledge of the Cisco VLAN Trunking Protocol (or VTP), so before I jump into that I will lay down what I have learned here.

VTP is Cisco propritary, Juniper and other switches might have equivlent commands but VTP only works on Cisco equipment. VTP basically advertises and synces information regarding VLANS to all switches on a network or to be more thorough, all switches in the same VTP domain.

SWITCH(config)# vtp domain YOURDOMAIN

Cisco switches running VTP can be configured into one of three modes (that I know of so far) and they are; server, transparent, and client.

SWITCH(config)# vtp mode server

This is the default VTP mode. A VTP domain must have atleast one switch configured as the VTP server so that information regarding VLANs can be propagated to other switches in the domain. On a server you can create, add, edit, and delete VLANs. Any of these changes are sent out to other switches on a VTP domain.
SWITCH(config)# vtp mode transparent

Switches running in transparent mode are said to not participate in the domain, and while that is technically correct they do play a part as a forwarding device between server switches and clients.
SWITCH(config)# vtp mode client
Client switches listen for updates from other switches via VTP advertisements and update their VLAN configs accordingly. This is dependent on a connection to a switch running VTP server mode. Also it is not possible to create, add, delete or edit VLANs on the client.

This is just the very tip of the iceburg regarding VLANS. I have to say that semester 3 cisco is by far the most interesting instruction I have had to date. The content is well writen and presented very clearly, where at times transparent concepts from previous semesters (such as how different routing protocols achieve network convergence) were clear as mud. Love this class, learning alot, wish I had time to write more.

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