From: Richard Hanks (ccieingroup@hotmail.com)
Date: Fri Jan 03 2003 - 03:14:52 GMT-3
Hi Friends,
I have a question here about the 3550 Port Priority. Please refer to the
"Catalyst 3550 Multilayer Switch Software configuration Guide.pdf" Chapter
10-26 Configuring VLANs (Load Sharing Using STP) and Chapter 14-15 configuring
STP( Configuring the port priority).
My question is if two 3550 connected by two trunk links like this one.
Switch A (Root Bridge)
0/1| |0/2
1/1| |1/2
Switch B.
I want to use the "spanning-tree vlan 20 port-priority ..." to make the Switch
B's 1/1 in forwarding state for vlan 20 but 1/2 in the block state. Where
should I put the "spanning-tree vlan .. port-priority" command on? I mean
whether on Switch A's port 0/1 and 0/2 or Switch B's 1/1 and 1/2. I mean
whether the upstream switch or downstream switch directly.
I also refer to the "CCIE Professional Development Cisco LAN Switching" Page
249: Port/VLAN Priority- "set spantree portvlanpri" can be used to load
balance between back-to-back switches. This technique allows network
administrators to modify port ID values(Port ID=Port priority + Port number)
on upstream switches to influence forwarding and blocking decisions on
neighboring downstream switches."
But I can't find any such description in the 3550 configuration guide. From
the example of page 10-26. Though it mentioned where to put the commands on,
but it didn't mention which switch is the root.
Appreciate for any help.
Rgds,
Richard
.
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