From: marvin greenlee (marvin@ccbootcamp.com)
Date: Fri Apr 29 2005 - 12:53:00 GMT-3
You can have multiple instances and map VLANs to each instance. If you have
two instances, for example, you could map the odd VLANs to instance 1 and
the even VLANs to instance 2. The switch only needs to compute two spanning
instances.
With PVST+ (Per VLAN Spanning Tree), the switch needs to compute a spanning
instance for each VLAN.
Cisco - Understanding Multiple Spanning Tree Protocol -
http://www.cisco.com/warp/public/473/147.html
Someone posted a link to a good article on basic configuration of MST a few
weeks back, so check the archives as well.
Marvin Greenlee, CCIE#12237, CCSI# 30483
Network Learning Inc
marvin@ccbootcamp.com
www.ccbootcamp.com (Cisco Training)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
kwasi-ccie@comcast.net
Sent: Friday, April 29, 2005 7:40 AM
To: ccielab@groupstudy.com
Subject: Help understanding MST [bcc][faked-from]
Importance: Low
Hi:
I am trying to understand how MST works. One aspect that I am not clear on
is the fact that for any switch to be part of an MST Region it must have the
same VLAN-to-Instance mapping, beside the same MST name and version #.
Does this mean all VLANs on a switch in an MST region can be mapped to only
one MST instance? For instance can I have VLAN 10 and VLAN 20 (on an MST
switch in an MST region) mapped to say instance s 1 and 2, respectively? Or
do they have to be mapped to only one instance such as instance 1?
If I can only map multiple VLANs to only one instance, then what is the need
for having instances 1 - 15 for internal MST switches?
I have read CCO but the examples are not clear enough for me on this issue.
Your comments are welcome.
Thanks.
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