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Impact of Changing VTP modes

jim-phillips
Level 1
Level 1

Quick question,

Best practices suggest that having a few core switches set as VTP Servers for redundancy while leaving the remaining switching infrastructure in either Client or Transparent mode. To further reduce the amount of VTP servers within a single VTP domain is it possible to:

1) Set an existing server to “Transparent” mode (to lower the configuration revision to 0, just to be on the safe side)

2) Set it to “Client”, as a client it would then receive vtp information from the remaining servers however nothing would change because the vlan database on that switch would not have changed at all. Only it's vtp mode would have changed.

Thus removing the excess VTP server, but will this cause any downtime to users or between devices? Keep in mind that each server currently has identical outputs of “show vtp status” all having the same configuration revision and number of vlans per switch. I've tested this on a small scale with three 3560 switches and had no loss of connectivity but I'm leery of pitfalls across a larger VTP domain containing 50+ switches.

What are the odds of this working seamlessly? Has anyone tried it on a live network?

Thanks,

Jim

1 Accepted Solution

Accepted Solutions

Edison Ortiz
Hall of Fame
Hall of Fame

Changing the VTP status shouldn't cause a disruption of services.

If you decide to change from VTP server mode to VTP client mode, the client will receive the Vlan information from the remaining VTP servers via its trunked switchports. (Note, please make sure you have trunking configured for VTP exchange between client/server and server/server).

If you decide to change from VTP server mode to VTP transparent mode, the switch will keep the existing Vlan information but it will not receive future Vlan modifications from the VTP server(s). You need to manually add/delete/modify Vlans on this switch. This is often considered as best practice since a change in a switch Vlan database does not affect the remaining switches in your network (Vlan Security).

HTH,

__

Edison.

View solution in original post

2 Replies 2

Edison Ortiz
Hall of Fame
Hall of Fame

Changing the VTP status shouldn't cause a disruption of services.

If you decide to change from VTP server mode to VTP client mode, the client will receive the Vlan information from the remaining VTP servers via its trunked switchports. (Note, please make sure you have trunking configured for VTP exchange between client/server and server/server).

If you decide to change from VTP server mode to VTP transparent mode, the switch will keep the existing Vlan information but it will not receive future Vlan modifications from the VTP server(s). You need to manually add/delete/modify Vlans on this switch. This is often considered as best practice since a change in a switch Vlan database does not affect the remaining switches in your network (Vlan Security).

HTH,

__

Edison.

Thanks for the reply,

It sounds like it won't be a problem to change a switch from server to client but I am curious about how that change effects the vlan database.

When you change from Server mode to Client the switch's vlan.dat already has the same entries as the other vtp server connected to it via trunk. Is the database entirely rebuilt or does vtp just fill in the blanks so to speak? In this case there are no blanks to fill in.

The documentation I've read didn't go into detail in that respect.

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