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New Member

IGMP Snooping with Multicast (local only)

I have a situation that has been driving me crazy. I would appreciate any advice.

In a few locations we are running old Nortel 450-24T's (with 1.48 / mixed with C2950-24's (with 12.1.22.EA8a).

I'm having a hard time getting Ghosting/ZenImaging to work smoothly on the network.

IGMP Snooping is enabled on both, however the Nortel only supports v1 and v2. The cisco defaults to 2 but supports 1 and 3 (somewhat). I have issues with machines not wanting to join the multicast session. I can issue the "IP IGMP Snooping Group" command and sometimes I see the groups joining and sometimes there's nothing.

Is there a known issue with IGMP between the two products? If there's any Nortel savy people around can you tell me something that's worked for you?

I did read on a newsgroup post somewhere that under the IGMP settings to disable "Proxy" as it causes issues. I did this and it did seem to clean things up somewhat.

I've been trying to read up on igmp snooping and multicasting but most articles keep talking about setups where your using it across wan/routers etc. We're just doing local stuff.

In the locations that I've been able to replace everything with Cisco I've simply enabled the default IGMP Snooping settings and I can image a 100 computers with no problems.

Thanks for any suggestions.

Take care.

New Member

Re: IGMP Snooping with Multicast (local only)

If your LAN gateway is a Cisco Layer 3 device, try enabling IP multicast-routing on the router that serves as the gateway for your LAN. Then on the LAN interface of the router enable ip pim sparse-dense-mode. See if that helps in your case of multi-vendor switches. This should allow the nortel igmp to snoop on the multicast router and get the information needed to help your imaging. When you enable pim on the lan interface only, it will keep multicast traffic inside your lan only.

New Member

Re: IGMP Snooping with Multicast (local only)

Thank you for your reply. I will try working on this later in the week, might be next week. We're working on other projects at the moment.

I'll read up on enabling multicast-routing at the gateway before I do this.

I read a little on the subject but every time I got to the part about using an mrouter I didn't think it was needed (unless I was doing multicasting via wan etc.) However, we're going to be moving to some new system that streams video via the WAN so I'm sure we'll need these features very soon anyway.

New Member

Re: IGMP Snooping with Multicast (local only)

You might have to take it to the packet level and find out why those hosts are not joining the multicast group.

Make sure the router/switch inteface is enabled for multicast and make sure the igmp versions are the same.

You can change the igmp version with

"igmp version" command on the interface of a router.

Make sure your router is querying the subnet properly and also participating in IGMP for that LAN segment.

New Member

Re: IGMP Snooping with Multicast (local only)

I noticed that the nortels can only do v1 and v2 and that you can force the ports to belong to the IGMP groupings (maybe if not using a mrouter?).

Were not using the multicast routing features (which I'm now seeing we need to setup). As long as the location had all one product with the default IGMP Snoop enabled, things seemed to do well. However, with our mixed environments it's been a nightmare. These nortels are very old and only after a software update (from archives) did they even have the feature to turn on IGMP Snooping. I've also read that vendors can alter how they implement IGMP (even when it's the same version). Which may be the reason we really do need to have the router doing mrouting. (I guess)

Thanks to both replies. I'm very new to this particular subject, hopefully we'll get this smoothed out in the next few weeks.

I'll post back when I've had time to look at it again.

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