- VTP is a cisco proprietary protocol.
- VTP is used to share VLAN information automatically between cisco switches.
There are few things that are taken into consideration when configuring VTP.
- The switches need to belong to the same VTP domain if you want them to share VLAN information automatically.
- VTP updates can only be sent via trunk ports, they cannot be sent via access ports.
- VTP has authentication feature, so if authentication is enabled then the passwords must match on all the switches.
- If a switch belongs to VTP domain null (nothing), then such a switch cannot originate VTP messages.
- By default cisco switches are configured with VTP domain NULL.
- A switch can be kept in one of VTP modes.
- VTP server switch
- VTP client switch
- VTP transparent switch
- These modes define how a switch will behave in VTP:
- How the switch will send VTP messages.
- And how the switch will receive VTP messages.
- VTP server switch is that switch we create, delete and modify VLANs.
- VTP server switches send updates with the help of which they provide VLAN information to other switches.
- VTP client switch receives information from VTP server switch, you cannot create, delete and modify VLANs on client switch.
- By default all the switches are in VTP server mode.
- BY default VTP is enabled on cisco switches.
- Configuration revision number value.
- CR number starts from 0 on all the switches, be it server switch, client switch or transparent switch.
- Whenever there is a change in the VLAN database, this value is incremented by 1.
- CR number value always remains 0 on the transparent switch.
- Transparent switches do not process VTP updates themselves, but they do act as a VTP relay agents.
- VTP Transparent switches maintain its own local VLAN database that it does not shares with anyone.
- It does not originate VTP messages itself.
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