All things related to multicast

[Bill Nickless <>]

Just yesterday I turned off CEF on a Catalyst 6509 with a MSFC running IOS 
(tm) MSFC Software (C6MSFC-IS-M), Version 12.1(1)E.  I am tunneling 
multicast by way of GRE offsite.  Unicast traffic was failing to be 
forwarded through the tunnel, being dropped on the floor.  Turning of CEF 
fixed the problem instantly.

Last week we discovered a bug with CEF on a Catalyst 8540.  We had two two 
OSPF default routes with different metrics (primary and backup border 
routers).  When anything changed in OSPF, the 8540 would stop forwarding 
packets and start generating ICMP Host Unreachables.  This took about 5 
seconds each time a link state changed on campus.  The bad news is that you 
can't turn off CEF on an 8540.  Making the OSPF default routes have the 
same metric, and carefully adjusting OSPF costs to get things to flow the 
right way, solved that problem.

At 11:16 AM 5/23/2000 -0400, S.Grant wrote:
> I have heard that there have been problems related to enabling multicast
> when cef is enabled.  However, I am unable to find anything related to this
> on the Cisco site.  The platform that is experiencing problems is a Cisco
> Catalyst running 12.1.1.  Any pointers would be greatly appreciated.

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Bill Nickless    http://www.mcs.anl.gov/people/nickless      +1 630 252 7390
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