IGMP Snooping Expert Needed !!

This command is supposed to dispaly the multicast routers

Thanks Merv!

I have a satellite dish on Fa0/2. I do not want the routers sending and recieving multicast data. What command can I use to remove or block the routers (Fa0/11 and Fa0/12)?

Thanks! Nick

The routers should not forward multicast traffic unless they are configured to do so - i.e. if you have configured a multicast routing protocol such as PIM on the router interfaces.

Routers will automatically join a number of 224.0.0.x groups since those groups are used by various routing protocols - OSPF, EIGRP, RIPv2, HSRP, etc.

Ok. My issue is when I run the below command it specifies port 12, which is the router. I need the below command to connect with port fa0/2.

Any ideas on how I can straighten out the command below to ignore the routers and connect to fa/2?

SWITCHO1#show ip igmp snooping querier Vlan IP Address IGMP Version Port

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Perhaps it would be best if you describe exactly what you are trying to accomplish.

For example you indicated you have a satellite disk connected to port Fa 0/2.

Is that the source for IP multicast streams ?

If so which ports on the switch are the multicast streams destined to?

You indicated that you do not want the data from the satellite going to the routers ports.

IGMP is a layer 3 protocol used between hosts and multicast routers to tell the routers which hosts want to receive a particular stream. IGMP snooping is a layer 2 switch kludge that allows the switch to figure out which ports should receive a particular multicast stream.

On a LAN, IGMP querier was introduced to reduce the amount of IGMP reporting traffic. AN IGMP querier is elected and only that router is the one that sends out group queries.

You can configure the switch to be an IGMP querier. Not sure if you can block the routers connected to the switch from being queriers. Perhaps someone else can provide the answer to that question.

Post a "show run" for the 2950 switch along with "show ip interface" from the two routers for each of the router interfaces connected to the switch inq question. Also check the output of ' show ip igmp groups" on the routers

Perfect!

Ok. The source of the multicast is fa0/2 (satellite dish) and the destination is on that same switch at fa0/4 (small desktop running xp pro).

The problem is when I start the multicast listening service on the small desktop running xp pro connected to fa0/4 the switch freaks out.

for example, when i show mac-address table command for the mac of the small desktop connected to fa0/4, the switch sometimes shows fa0/4, fa0/11 or fa0/12. In other words, the pc is directly connected to fa0/4; but, somehow the switch sometimes thinks the mac address is forwarded out fa0/11 or fa0/12 to the routers.

If I disable the multicast listening service on the xp pro box connected to fa0/4, and I then do a show mac-address table the result is consistent and correct of fa0/4. fa0/11 and fa0/12 never show up when the listening service is disabled.

everyone here is stumped and we have never seen this before. this is why i was thinking maybe if i could block or remove the router ports maybe the mulicast would operate correctly.

not sure what to do at this point.

configs are coming....

Thanks! Nick

Perhaps you should disable IGMP snooping to se if that is the cause of your grief