MSTP compliant & vlan 1002 1003 1004 1005

Unanswered Question
Nov 13th, 2009

Hi all.

I am going to set up MSTP using cisco & hp.

But in my cisco 6500 switch I have those vlan 1003 1004 1004 1005 wath do i do with them? do I create them in all switch (cisco & Hp) and then I add them to MST instance?


I have this problem too.
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Giuseppe Larosa Fri, 11/13/2009 - 04:44

Hello Osvaldo,

these are legacy Vlans to be used for FDDI and token ring.

actually a modern IOS switch without FDDI or TR ports cannot use these vlans.

leave them on instance 0 and don't use them.

Hope to help


languedoc Fri, 11/13/2009 - 05:12


I thank you very much for your answer.

But i have read that for proper MSTP functioning all switch must have the sames vlan even if they do not use them all, even if somes are denied with switchport trunk allow command. Am I rigth?

Thanks again.

Giuseppe Larosa Fri, 11/13/2009 - 05:43

Hello Osvaldo,

that's correct make a coherent choice on all your devices associate the legacy vlans to the same MST instance.

This is needed to avoid unwanted partitioning of MST regions.

As I wrote in first post you cannot use the legacy vlans on Cisco devices.

Hope to help


Francois Tallet Fri, 11/13/2009 - 08:20


Don't worry about the vlans. For MST, what count is the vlan to instance mapping. Basically, the lines in the "mst configuration" and that is used to define the region. If the region definition match, you can use several instance, if they don't, all your vlans will follow the topology of instance 0 (thus no load balancing possible).

MST does not care about whether a vlan is defined or not. MST does not run on a vlan, does not use vlan. It computes the topologies of MST instances independently of vlans. Then vlans are mapped to those topologies.




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