multicast down at ku, may explain utah outage as well

Rogier, Gordon grogier at
Tue Aug 29 15:43:02 CDT 2000

ag-tech list, fyi.  :grogier.

---------- Forwarded message ----------
Date: Tue, 29 Aug 2000 15:41:11 -0500 (CDT)
From: Gordon Rogier <grogier at>
Reply-To: problem at
To: problem at
Cc: problem
Subject: Re: [Req #316] KU Multicast Service Problem

I interacted with Matt Davy (assigned to the GPN ticket opened on this
issue).  Matt understands the technical issue and the cause.

This problem is a know mroute-cache bug that was identified in the recent
Abilene GSR upgrade to 12.0(11.3)S and apparently more specifically in
the micro-code implementation for the line cards (which makes this a more 
dicey issue to diagnose). Abilene has been working exhaustively
with Cisco to resolve this new bug.  This problem intermittently causes
random (S,G) multicast flows to drop packets.  There is no easy work
around.  The only effective work around at this time in Abilene GSR is to
disable the distributed route caching, which pegs the routing processors!!
Not a feasible workaround.

Abilene is expecting (starting tomorrow morning) to try some new

Abilene indicated this multicast problem openly at the
NLANR/I2/CANARIE meetings last week in Toronoto Canada. This problem is
rearing it's ugly head all over Abilene.  I have it on direct words from
several Abilene engineers that they are currently wrestling with the best
resolution to this situation, including possibly falling back on a code
level in the Abilene routers.

So, for tonight pending new information, I am inclined to leave things as
is on this issue and check back with Matt Davy in the morning.

Gordon Rogier                        grogier at            
Network Engineer                     785-864-0381wk 785-550-4468 cell
Great Plains Network                 785-864-9330 FAX

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