VTP Transparent Mode in 2924XL/3524XL

[alwhitlow]

I have a 2924XL ver12.0(5)WC11 connected to two 3550 ver12.1(22)EA5 via 802.1Q trunks. They are all in the same VTP domain. The 2924XL is in VTP Client mode & the two 3550s are in VTP Server mode. There are only 6 vlans - 1, 223, 1002, 1003, 1004, & 1005. I am attempting to change all switches to VTP Transparent mode.

Starting w/the 2924XL, when I change mode from VPT Client mode to VTP Transparent mode, the interfaces w/the trunk links immediately bounce & when they come back up, communication is only established thru VLAN1 & am no longer to communicate to devices in VLAN223.

Connection was restored when I reconfigured the 2924XL back to VTP Client mode.

What is causing this problem & what is the proper way to convert to Transparent mode w/o interruption of service?

Thanks!

[glen.grant]

Why because the server supplied the vlan info to the 2924 in client/server mode and when you change it it is no longer there . All you should have to do is create the layer 2 vlan info manually on the 2924 in the vlan database . Not sure if you can do this without downtime because I believe you have to be in transparent mode to create the layer 2 vlan . should be a very short outage if you know how to do this though.

[alwhitlow]

But the vlan info is there, when performing a "show vlan" both VLAN 1 & VLAN 223 appears including the ports that are assigned to each VLAN.

Also note, this scenario was reproduced at another site w/the same setup.

[glen.grant]

Does the vlan show active when displaying the vlans , sometimes they can get into a suspended or inactive state and you just have to reenable them .

[ariela]

Humm ...

well, please help me to understand the problem.

The VTP Client saves the vlan infos in RAM, and not in NVRAM like VTP Server ... when you change the VTP mode Client to Transparent, why you lose you vlan infos?

If you do a "sh vlan" on one of your switches that is in client mode, then change it to be in transparent mode, none of them would disappear.

It will simply stop listening to vtp messages regarding the creation and deletion of vlans.

Then, of course, you have to create the vlan database in NVRAM ...

Thanks for your support

Regards

Andrea

[ananddiwakar · Accepted solution]

To add to the above posts, one more place you should look for the issue is trunks between 2924 and 3550s. If you have only these 3 switches in the network, and if you have enabled pruning, better disable it on both the servers and check your trunk configuration.

[alwhitlow]

That appeared to be the problem. After I disabled VTP pruning on the server, (you can only disable pruning in server mode & it auto propogates to the clients) I was able to convert both server/clients to transport mode w/o any interruption of service.

Thanks for all the suggestions!!