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Community Member

Multicasting (IGMP Snoop) between Nortel and Cisco

We are currently having issues with Zen imaging (multicasting) and our setup is the following.

Please take into account, our knowledge is very limited with IGMP Snooping setup etc.

MDF = 6 Nortel 450-24T's using FirmWare -1.48 / SoftWare -

IGMP Settings are such :

VLAN: [ 1 ]

Snooping: [ Enabled ]

Proxy: [ Disabled ] -----> This was on...but once off, runs much smoother.

Robust Value: [ 2 ]

Query Time: [ 125 seconds ]

Set Router Ports: [ Version 1 ]

In the MDF (anythig directly in those switches) images fine now. (once I disabled PROXY)

However I have a few IDF's off the MDF that are using OLD Nortel 350F-HD's (no IGMP Snooping support) and it's horrible (can only do a few computers at a time.

So in one of the IDF's (the biggest one) I pulled out the 350F-HD and replaced it with a CISCO 2950 w/Fiber and it's using 12.1.20EA1 and I left IGMP Snooping on (thinking this will fix it) and couldn't even get ONE machine to connect and image in the multicast session. It's settings were (by default):

Global IGMP Snooping configuration:


IGMP snooping : Disabled

IGMPv3 snooping (minimal) : Enabled

Report suppression : Enabled

TCN solicit query : Disabled

TCN flood query count : 2

Vlan 1:


IGMP snooping : Disabled

Immediate leave : Disabled

Multicast router learning mode : pim-dvmrp

Source only learning age timer : 10

I then completly disabled IGMP Snooping on the CISCO and we're able to Image 5-7 Computers without a crash (more than that and it crashes - disconnects etc)

In the area's that I have All 450's or all CIsco's the imaging seems to go fine. (with minor errors)

Can any one give me some advice (or hopefully ran into this mixed setup before)?

Thank you.


Re: Multicasting (IGMP Snoop) between Nortel and Cisco

Are the image source and the recievers in the same vlan? If so, is there a L3 device? Eventhough the sender of the image and the requester are in the same vlan, igmp snooping needs a querier, the querier can be a L3 devices and all it need is "ip pim" under the interface vlan 1. Or an igmp querier. For more info on querier:

IGMP querier enables IGMP snooping within a VLAN where PIM and IGMP are not configured because the multicast traffic does not need to be routed.

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Community Member

Re: Multicasting (IGMP Snoop) between Nortel and Cisco

Yes the source/recievers are in the same vlan (one flat network), yes we have L3 (Cisco 2600 series).

I've looked at the article you pointed me to (thank you) however it seems the Cisco 2950's don't support "IGMP querier". :( I don't know anything about the "IP PIM" (I'll read up), however I do know that in other pure cisco setups I've just enabled snooping and it's worked great. hmmm. (although this is a mixture or nortel/cisco, so that's a big difference).

Thank you for your reply.

Re: Multicasting (IGMP Snoop) between Nortel and Cisco

Try this, on the 2600, enable ip multicast routing and on the interface serving the vlan having problem put under that interface "ip pim dense-mode" or "ip pim sparse-mode", it just need an ip pim. ON the pure Cisco set-ups, it might that the receiver and sender are in different vlans and there are routers routing the multicast. If it's flat and receiver and sender are in the same vlan and igmp snooping are enabled, you should run into the same issue. Check if that's the case.

Please rate helpful posts.

Community Member

Re: Multicasting (IGMP Snoop) between Nortel and Cisco


Thank you for replying (and I read even more on the ip multicast routing). However I've not ran into the same issue at any school that has 100% cisco switches or 100% Nortels (that are setup correctly and not older than dirt). I think we've not needed the multicast routing setup as we only have one router on the network (and it's flat at the moment anyway). As long as IGMP Snooping is enabled correctly (on the switches) it seems to serve us well.

Although from what I've read (where you pointed me too) it seems even in our setup we would benifeit from taking time to setup "ip pim ....." etc.

I was able to scrounge from another network and change out a few very old Nortels (that didn't support IGMP Snoop) and all seems well now.

So long story short (and incase anyone else needs this info. The Nortel 350T and F - HD's were the main issue. It seems (for now) that a mixture of Nortel 350/450-24T's (any model that at least has IGMP Snooping) and Cisco's mixed (also Snoop on) works pretty well.

I'm going to consider this solved as I was able to fix it with changing out some old product. However I really appreciate your efforts and pointing my towards some good info. (Which I'm going to read up on more, as I'm sure we'll need to get it setup in the near future.)

Thanks again.

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