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vtp question

When setting up trunks as desirable even in transparent mode the vtp domain name has to match on each end in order for the trunk to form. Our dilemma is this ,each of dist layer boxes has a different vtp domain name so when we setup a switch and it needs dual connections (hsrp) then we can only have the one vtp domain name . Is the only option to force on the trunk on the secondary side and or force on both sides ? We prefer to negotiate the trunks but do not see way around this. Our dist layer is cat 6500 in hybrid mode , believe they are running vtp version 2. I have never been able to get a trunk to come active even in transparent mode without having matched vtp domain names. Am I missing something here ????

Jon Marshall
VIP Community Legend

Hi Glen

As far as i know you need to match the domain name to form a trunk so you will need to set it explicitly. In addtion you need to set it on both ends not just one of them.

Be glad to hear from anyone else if there is a way round this.




AFAIK vtp version 2 supports only single doamin.Even though transperent mode forwards the frame without checking the domain name the other end switch will discard it if unmatched domain.So you have to have same domains on both switches.

Regarding the desirable trunking with different domains i will like to hear more from experts.


shri :)

Hi ,

In DTP,u need to have VTP domain same...then only trunking will be formed...


So I take it from the answers that the only answer in this case is either force both sides on or let one side negotiate and force the other side on due to the vtp domain name issue.

Thanks for the replies..


When i tested this having one side forced to trunk and the other dynamic desirable the trunk failed to come up on the dynamic desirable switch. Tested with 3560 switches.

So i would recommend configuring both ends to be on explicitly.


Thanks Jon , it is the same in all my testing too so i just wanted to verify with smart minds in here just in case I was missing something. thanks for your help..

Jon did a little more testing and I did not see a problem having one as desirable for the ports that were connected to another switch with the same vtp domain. The other side all that has to be done is to set the ports as trunk nonegotiate. On the catos it as simple as "set trunk slot/port nonegotiate. Reloaded multiple times and the trunks always came back up and could ping between everything. Obviously forcing both sides would also work .

Thanks for your input.