The answer to this question depends on which Catalyst switch you are talking
about. The 2900XL's can have up to 68 VLANS and therefore you would be able
to have 64 instances of spanning tree running. Show vtp stat will show you
the possible number of vlans on your hardware.
You your second question regarding how many priority numbers: each instance
of spanning tree will have a root bridge chosen by the priority and mac
address. Therefor, whichever switch wins the root war, will be root for all
instances of spanning tree. You can force this per instance with a
spanning-tree priority command and set the cost and the assigned vlan #.
Clark & Hamilton in the Cisco Lan Switching book recommend 100 for your root
bridge and 200 for your backup root bridge.
HTH
MikeN
Network Engineer
""Ash Aslam"" wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> How many STP are possible to have on one Catalyst Switch?
>
> Can anyone confirm if each VLan has it's own Spanning Tree priority
number?
>
> The above (second) question is in reference to Bruce Caslow's explanation
in
> BRS Vol. 1, Page 821, last sentence in Paragraph 2.
>
> Any thoughts!
>
> Thanks & Regards,
> Ash
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=10761&t=10724
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