From: Brant Stevens (branto@xxxxxxxxxxxxx)
Date: Fri Oct 05 2001 - 17:36:16 GMT-3
I believe as of version 5.5.x, it supported 2 other STP modes, MISTP+, and
MISTP-PVST+... I haven't done much reading on the latter, but the former is
pretty simple... When using 802.1q, you can have VLANs with the same
topology use the same instance of STP to eliminate loops, as opposed to
having a separate STP instance for each VLAN.
Given the topology below:
+-----+ +-----+
| | | |
| SWa |-----| SWb |
| | | |
+-----+ +-----+
| |
\ /
\ /
+-----+
| |
| |
| SWc |
| |
+-----+
(ASCII Art is a real pain in the ass... have you seen some of the web pages
out there with ASCII Art?!?!?! geez... anyway, I digress...)
If there were 15 VLANs on the above network, numbered 1-15, and SWa was the
root for VLANs 1,3,5,7,9,11,13, and 15 while SWb was the STP root for VLANs
2,4,6,8,10,12, and 14, and all these VLANs had active ports on SWc, when
using PVST+, the Catalyst would create a separate instance of STP for all
these VLANs, when logically the odd VLANs have the same topology, as do all
the even VLANs.
In the above scenario, MISTP+ would create 2 instances of STP, one for the
even VLANs, and one for the odd VLANs.
I don't know the impact this has on switch CPU resources and memory, but it
seems that in an environment with many VLANs this could prove very useful...
HTH,
Brant.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Joseph Ezerski
Sent: Wednesday, October 03, 2001 7:22 PM
To: 'Nabil Bukhari'; ccielab@groupstudy.com
Subject: RE: question regarding support for per VLAN STP in cat 6500
Yes, of course..the 6509 can do just about anything except tell you about
the one day lab ;)
In reality, it has supported that for a long time. If you use ISL, you
automatically get PVST. If you chose to use 802.1q trunking (my choice)
then you automatically get PVST+ which really just tunnels PVST across a
dot1q trunk. I do not know in which particular version they first supported
this, but I would venture to say that anything above 5.1 should suffice.
You may want to check CCO if you are in doubt.
-Joe
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Nabil Bukhari
Sent: Wednesday, October 03, 2001 3:48 PM
To: ccielab@groupstudy.com
Subject: question regarding support for per VLAN STP in cat 6500
hello guys
coudl someone tell me if some software release supports usage of per VLAN
STP on cisco cat 6500
thanx in advance
nabil
This archive was generated by hypermail 2.1.4 : Thu Jun 20 2002 - 22:33:14 GMT-3