[nsp] Speaking of Multicast

[Gert Doering]

Hi,

On Tue, May 18, 2004 at 10:45:56AM -0400, christopher_a_kane at bankone.com wrote:
> I was wondering what lessons some people have learned. Not in regards to 
> implementation or design but rather, operations support. What are some of 
> the common problems seen (mostly application related?), what 
> troubleshooting methods have worked best, etc...

Inter-AS multicast seems to be dying a slow and painful death.

It's nearly impossible to debug, as all major telcos seem to have lost all
multicast clue - and unlike unicast (where you can run a traceroute to
and from your network) multicast debugging really needs some to take a
close look into all intermediate networks - "is the MSDP SA visible?  Is it 
being sent? Have PIM joins built a tree?  If not, why not?".

Inside a single PIM RP domain, multicast usually "just works", unless
someone forgot to switch on PIM on an intermediate link between source
and receiver, or someone is injecting bogus RP announcements... (and yes,
both tend to be painful to debug).

gert
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Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de