VTP

 Before you add any switch to the network you need to get in the habit of checking the VTP configuration and make sure the VTP Configuration Revision number is set to 0. You can do this by console in to the switch and type in sho vtp status, if the revision is not 0 then do write erase and reload. This will put your switch to manufacture default. If you don’t do that and the Configuration Revision on your network switches is lower then your new switches  your  Vlan nodes will be down and you just created a big problem.

SW1#sho vtp status
VTP Version                     : 2
Configuration Revision          : 0
Maximum VLANs supported locally : 255
Number of existing VLANs        : 5
VTP Operating Mode              : Server
VTP Domain Name                 : ciscosteps
VTP Pruning Mode                : Disabled
VTP V2 Mode                     : Disabled
VTP Traps Generation            : Disabled
MD5 digest                      : 0x7D 0x5A 0xA6 0x0E 0x9A 0x72 0xA0 0x3A
Configuration last modified by 0.0.0.0 at 0-0-00 00:00:00
Local updater ID is 0.0.0.0 (no valid interface found)

VTP Server:

• Power to change vlan info
• sends and receive VTP updates
• saves Vlan config

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SW2#sho vtp status
VTP Version                     : 2
Configuration Revision          : 0
Maximum VLANs supported locally : 255
Number of existing VLANs        : 5
VTP Operating Mode              : Client
VTP Domain Name                 : ciscosteps
VTP Pruning Mode                : Disabled
VTP V2 Mode                     : Disabled
VTP Traps Generation            : Disabled
MD5 digest                      : 0x7D 0x5A 0xA6 0x0E 0x9A 0x72 0xA0 0x3A
Configuration last modified by 0.0.0.0 at 0-0-00 00:00:00

VTP Client:

• can't change vlan info
• sends and receive VTP updates
• does not save Vlan config

=======================================================

SW3#sho vtp status
VTP Version                     : 2
Configuration Revision          : 0
Maximum VLANs supported locally : 255
Number of existing VLANs        : 5
VTP Operating Mode              : Transparent
VTP Domain Name                 : ciscosteps
VTP Pruning Mode                : Disabled
VTP V2 Mode                     : Disabled
VTP Traps Generation            : Disabled
MD5 digest                      : 0x7D 0x5A 0xA6 0x0E 0x9A 0x72 0xA0 0x3A
Configuration last modified by 0.0.0.0 at 0-0-00 00:00:00

VTP Transparent:

• Power to change vlan info
• forwards VTP updates
• does not listen to VTP updates
• saves Vlan config