[AG-TECH] multicast config (Nortel) ?

Andrew Daviel advax at triumf.ca
Fri Feb 7 00:41:14 CST 2003

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I'm having some trouble configuring multicast routing and
wondered if anyone had any experience with Nortel equipment
(or just general advice).

We have a Nortel Passport 8600  (8603 ?) router and BayStack 450 switches.
We are connected to CA*net and hence Internet2 via BCnet.
See Fig 1 (attached).
We have a static RP set on the passport using an address supplied by 

We have 3 ports on the router grouped into a VLAN feeding our network 
which is a flat class B. We have SGMP snooping enabled on the switches, 
currently version 2 I think, plus multicast throttling after the SQL 
Slammer fun & games. I think there is PIM sparse mode enabled on the 
router; I am not sure whether IGMP snooping is turned on on the router; I 
have been playing with settings trying to get it to work.

Currently, if I fire up SDR, stations A & B can see announcements from the
Internet, but C and D cannot. (D is my desktop so it's really annoying...)  
If I send simple multicast packets from A,B,C or D then the other stations
can see them (this is a tiny ping-like thing I hacked together from a CS
course assignment somewhere). If I create sessions in SDR on one of the
stations then the others can see them, usually. D will see C immediately,
A will see B immediately, and there may be a delay for A to see C or D.

We recently tried a test to a site on CA*net from B using static 
ip addresses e.g. "vic". We could see them but they could 
not see us. It occurred to me later that I may not have started vic with
a big enough TTL; I think I had set the threshold in the Passport to 15.

Years ago we had the Mbone working with mrouted and a tunnel - only two
parameters, an address and a threshold. Now it is much more complex with 
PIM, IGMP, DVMRP etc. so I am getting a bit confused.

Ideally I would like multicast to work anywhere on site, and we would like 
to restrict the multicast data e.g. AG video from going down branches 
where it is not required, which I think is what IGMP snooping will do for 
us. So I'd like to understand what it is about port 4 and port 6 that 
means one works and one doesn't (I can't see any config differences).
And of course I would like to be able to send offsite.

Suggestions ?

Anyone know a good introduction to multicast networking, preferably 
free & online - though a good book would work too ?

Andrew Daviel, TRIUMF, Canada
Tel. +1 (604) 222-7376
security at triumf.ca
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