Default VLANs in VTP Domains

[mthomas]

Here's the question: Take ten switches, put five in one VTP domain (VTP1) and five in another (VTP2). If they are all in the same VLAN (vlan 1 for instance), can there be a root bridge for switches NOT in the same VTP domain? So could the five in VTP domain 1 have a root switch in VTP 2?

[tstevens]

VTP config has little to do with spanning tree. The answer to your question is, there will be one root for all switches in a given vlan, provided you have an access or trunk link with that vlan interconnecting the two domains.

[fkseow]

Hi Steven, as you mentioned that something need to be done in the STP, so is there any configuration sample over the Cisco website or else you have one which be shared with us ?

Thank you.

[mthomas]

Okay, let's take this a bit further. Lets say the five switches are in vtp1 are in the default vlan (vlan1) on a cisco switch, and the other five switches are in vtp2 also in the default vlan (vlan 1). Under that scenario, you are saying VTP would not come into play, and the root bridge for all of the switches (including those in the named vtp domain vtp1) could be a switch in the named vtp2 domain. Is this correct? This is what you've said could happen, correct?

Finally, let's say the first five switches are in vtp1, default vlan (vlan1) on a cisco switch, and the other five switches are in vlan 1 from some other company......then it wouldn't work for sure, don't you think?