multicast down at ku, may explain utah outage as well

Rogier, Gordon grogier at
Wed Aug 30 13:20:11 CDT 2000


I interacted with Matt Davy earlier this morning.  He did not come up with a
workaround this morning to the issue, but in doing his testing he did
effectively resolve access (at least for the moment) for KU and Utah (really
more precisely transit mcast traffic via the KSCY Abilene router).

Side notes, Matt said specifically using the 12.0(11.3)S GSR code, they have
seen these problems on Eng 0 OC-12 ATM, Eng 0 OC-3 POS and Eng 2 OC-48 POS
interfaces within Abilene.

Now I know that Matt is planning on pressing Cisco yet today to see where
they stand on the bug identification and resolution.  I know that it's
Abilene's preference to try to move forward and not go backward.

Again, I know that Abilene is frustrated with this issue and is analyzing if
the best decision is to wait for a bug fix or fallback... clearly falling
back has implications on other services and work within Abilene.

BTW, I am also aware of another mcast bug that Abilene is working on that
relates to mcast across frame-relay on POS.  I have not seen or been aware
of any effect this has had on the AG.... I think it mainly relates to mcast
service points that are not part of the AG sites.


> -----Original Message-----
> From: Bill Nickless [mailto:nickless at]
> Sent: Tuesday, August 29, 2000 4:06 PM
> To: Rogier, Gordon
> Subject: Re: multicast down at ku, may explain utah outage as well
> Gordon, thank you for forwarding this message to ag-tech.
> I'm curious if you know which line card(s) are affected on the GSR.
> I'm running 12.0(12.5)S on my border GSR and haven't seen 
> this problem 
> (yet).  But the only line cards I have are the Engine 0 OC-12 ATM and 
> Engine 1 Single-Port Gigabit Ethernet.  I do not have any POS line 
> cards.  Of course Abilene uses POS for their wide area links.
> Any intelligence you may have on this would be great.
> Thanks again,
>    Bill Nickless
> At 03:43 PM 8/29/2000 -0500, Rogier, Gordon wrote:
> >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
> >workarounds.
> >
> >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
> ===
> Bill Nickless      
> +1 630 252 7390
> PGP:0E 0F 16 80 C5 B1 69 52 E1 44 1A A5 0E 1B 74 F7     
> nickless at
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