[AG-TECH] FYI: Cisco bug causing multicast problems

Tollbom, S Cullen Cullen.Tollbom at pnl.gov
Mon Apr 22 11:30:48 CDT 2002

I've seen this problem here at PNNL as well.

The bug also seems to be present in the Cisco IOS 12.1(8)E through 12.1(11)E,
and the mainline code of 12.1(8) through 12.1(14).  It may extend further.  This
is on Cisco Catalyst 6509 MSFC2s and Cisco 7507s.  The situation worsened as we
started deploying version of Cisco IOS that included fixes for SNMP
vulnerabilities a couple of months back.

I've also run into sometimes severe packet-loss problems routing multicast
packets through VIP2 ATM OC3 ports and or into attached LANE clouds through
Catalyst X6101 ATM LANE cards.

One thing thats seems to help is turning off CEF and DCEF in the routers, but
then so much for performance.

Cullen Tollbom
Network Engineering
Pacific Northwest National Laboratory

-----Original Message-----
From: bernholdtde at ornl.gov [mailto:bernholdtde at ornl.gov]
Sent: Friday, April 19, 2002 12:38 PM
To: ag-tech at mcs.anl.gov
Cc: bernholdtde at ornl.gov
Subject: [AG-TECH] FYI: Cisco bug causing multicast problems

This has bitten us a couple of times in the last few weeks as people upgrade
routers.  I thought I'd mention it here in the hope of helping others recognize
the nature of the problem a little more quickly.

Symptoms: multicast is "one way", i.e. you can see and hear a remote site, but
they can't see or hear you.  The BeaconServer shows it too.

Our local multicast networking expert tells me that the Cisco IOS bug id for the
problem that causes this is CSCdx11848, and it is first found in IOS version

I'm sure that are other things that can cause similar symptoms, but we've had
two or three cases from this source in the last few weeks, sometimes with sites
we talk to regularly on AG.
David E. Bernholdt                   |   Email: bernholdtde at ornl.gov 
Oak Ridge National Laboratory        |   Phone: +1 (865) 574 3147    
http://www.csm.ornl.gov/~bernhold/   |   Fax:   +1 (865) 574 0680    

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