From: Venkataramanaiah.R (vramanaiah@gmail.com)
Date: Mon Mar 12 2007 - 06:42:27 ART
Hi, I have a topology as shown below
ABH-C-1 ----------- APC-C-1 --------- Edge-Sw-1 ---- Host A
| | \
| | \
| | \------- Edge-Sw-2 ---- Host B
| |
ABH-C-2 ----------- APC-C-2
I have two MSTP instances running in the network, namely instance 0 and
instance 1.
Vlans 1-500 belong to instance 1 and the rest belong to Instance 0.
Hosts A and B are in Vlan 200 (which means they belong to Instance 1).
ABH-C-1 is the root and APC-C-1 is the backup root for Instance 1.
APC-C-2 is the root and ABH-C-2 is the backup root for Instance 0.
This forces the link between ABH-C-1 and APC-C-1 to be active for Instance 1
and the link between APC-C-2 to ABH-C-2 to be active for Instance 0.
The problem that i have in hand is, RSTP convergence delay when the link
between C1 to C1 fails.
I have continues pings going between Host A and Host B, which are directly
connected to APC-C-1. When the ABH-C1 to APC-C1 link is broken, it takes
about
20 or more seconds for the Spanning tree to converge. Agree the primary link
to the spanning tree is lost, so RSTP has to reconverge, but i am surprised
to see why it should take
20 seconds for this..? RSTP is supposed to reconvergence in sub-seconds.
Fyi, there is no impact when the link between C2 - C2 is broken.
I am puzzled to see that RSTP takes such a long time to converge in such a
small network with 6 switches.
I want to know, is there anything wrong with the topology.. Is this expected
behaviour for this topology..?
Btw, i wont be able to recreate this setup now, because it is dismantled now
and i wont be able to rebuild it for now. So, let us debate just on the
theory why this should fail.
Regards
-Venkat
This archive was generated by hypermail 2.1.4 : Sun Apr 01 2007 - 06:35:51 ART