Dot Q Trunking betwen two VTP server switches with different VTP Domains

swharvey · ‎10-10-2007

Can 802.1Q trunking be done between two Cisco switches (i.e. 4506's) that reside in different VTP Domains, but have a common vlan that is configured to pass traffic between the two switches?

We have a scenario whereby we need to connect two switches to one another via an 802.1q trunk, and need to pass L2 traffic between the switches. I'm hoping there is a way to override the DTP settings that prevent a trunk from establishing between switches. I have manually defined a common vlan on each VTP switch (each switch is a VTP server but resides in a separate domain/pw). I'm not looking to update vlans between switches, just trying to get the trunk up and to pass traffic over the common vlan that is manually configed on each switch.

Any help is appreciated.

Thanks,

-Scott

Francois Tallet · ‎10-10-2007

Note that if you only need to carry a single vlan between those two switches, you don't need a trunk. You can use an access port and forget about VTP;-)

Else, it's only the trunk negotiation that will fail between switches in different region. By using the on or nonegotiate modes, there should be no problem.

Regards,

Francois

Jonathan Hall · ‎10-11-2007

Be aware if you are running VTP pruning in either of the VTP domains I'd suggest you disable pruning on the trunk that connects the two domains.

I got caught out by this recently.

Jonathan

swharvey · ‎10-11-2007

We are running pruning, but I plan to run the "switchport trunk allowed vlan x, y" command on the interfaces that will be trunking between the two switches in separate vtp domains. Do you see any expected problems usnig this approach?

Thanks,

-Scott