VLAN Trunking Protocol (VTP) Notes
VLAN Trunking Protocol (VTP)
– Domain name
– Configuration revision number (CRN)
-> 32 bit
-> To maintain synchronization of VLANs
– Version 1 | 2 | 3
– No difference between version 1 and 2
-> contrary to theory
-> Version 1 doesn’t support tolken ring
– Version 1 and 2 can only propagate up to VLAN 1001
– Version 3 supports up to VLAN 4094
– Version 3 more secure
-> Concept of a primary server
-> Only primary server can update VLAN database
VTP messages
-> Summary Advertisement
-> Sent every 300 seconds
-> Domain name
-> CRN
-> MD5 hash
-> Version
-> Number of subset advertisements following
-> No actual VLAN information is present in this message
-> Subset Advertisement
-> VLAN name
-> VLAN ID
-> VLAN MTU
-> Advertisement Request
-> First client that receives the request can respond
-> Sent towards the server
-> Pruning Message
-> Pruning VLAN information
conf t
SW1(config)# vtp version { 1 | 2 | 3 }
vtp domain <name>
vtp password <password>
vtp pruning
-> Default domain name is NULL
-> only the vtp password command is needed on clients
# sh vtp status
MD5 hash = password + CRN
-> make a VLAN change
-> or wait for 5 minutes
Routers do not send pruning advertisements
-> use this to prune VLANs instead
-> SW1(config)# switchport trunk allow vlan <vlan>
Manual disabling of pruning
SW1(config)# int fa0/0
switchport trunk pruning vlan except 40
# sh int trunk
-> lists pruned VLANs
# sh int fa0/0 pruning
