VTP Domains

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Sep 14th, 2010
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I have an environment in which i have 10 switchs  & 2 domains - Domain A and Domain B

I want to know If i create Vlan 3 in Domain A and Domain B, can vlan 3 data be carried across both domains on a trunk configured with vlan 3, even though vtp advertisements will not cross domains?

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Peter Paluch Tue, 09/14/2010 - 08:52
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Yes, if you create the VLAN 3 in both domains and also allow the VLAN 3 on the trunk interconnecting these two domains then the VLAN 3 will span both domains and will be fully functional.

The only caveat to watch out for is that if you are using VTP Pruning then you must declare the VLAN 3 on the trunk between the two VTP domains as ineligible for pruning. The reason is that the VTP Join messages sent from either side of a trunk will be ignored on the other end because of the VTP domain name mismatch, thus no information about used/unused VLANs will be accepted by either switch, and as a result, all VLANs will be pruned off this trunk. Therefore it is necessary to force the VTP Pruning to leave the VLAN 3 alive on this trunk.

Best regards,



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