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New Member

Multicast Ghost and a 2950

I am having trouble with Ghost multicast on a 2950. What do I need to configure on the 2950 for Multicast to work with ghost?

The following is enable on the router.

ip pim dense-mode

ip cgmp


Re: Multicast Ghost and a 2950

Hi Randy,

If the hosts are in the same VLAN then you don't really need to configure anything, if they are in different VLANs then have you added "ip multicast-routing" to your router?



New Member

Re: Multicast Ghost and a 2950

It is on the same vlan and I do have multicast routing enable also. Igmp snooping is enabled on the 2950 switch. Does the 2950 require anything else.

Re: Multicast Ghost and a 2950

Where is the stream coming from? Are the multicast recievers having problem only happening on user in 2950? Is this only happening on a single vlan? Do you know which group id is having issue? Do you have any reason why there is ip cgmp on that interface?

can you provide the following:

from the router:

show ip mroute >> LOOK at the OIL and see if the interface going to that vlan is forwarding.

show ip igmp >> looking for a reporter.

from the switch:

show ip igmp snooping mrouter vlan vlan-id

show ip igmp snooping vlan vlan-id

All of the above is assuming that the mcast is routed, if the streamer and the receiver are in the same vlan, the 2950 should work as is. Also, you can try on the 2950:

no ip igmp snooping >> This will flood the mcast to all the ports and we can use this to isolate if the mcast is getting to the 2950 and it's igmp is not working.

Please rate all posts.

New Member

Re: Multicast Ghost and a 2950

The client and server are on the same subnet. The user had to disable something involveing McAfee ver. 8. The multicast ghost is working. But the router is being driven to 100% and it's killing the network. I am assumming that it is flooding the net with multicast.

BL-1#show ip igmp snooping vlan 1

Global IGMP Snooping configuration:


IGMP snooping : Enabled

IGMPv3 snooping (minimal) : Enabled

Report suppression : Enabled

TCN solicit query : Disabled

TCN flood query count : 2

Vlan 1:


IGMP snooping : Enabled

Immediate leave : Disabled

Multicast router learning mode : pim-dvmrp

Source only learning age timer : 10

CGMP interoperability mode : IGMP_CGMP

BL-1#show ip igmp snooping mrouter vlan 1

Vlan ports

---- -----

1 Fa0/23(dynamic)

Fa0/23 is the interface that connects to the router.

Should the learning mode be cgmp intstead of PIM.

Re: Multicast Ghost and a 2950

multicast being flooded on the switch might not have nothing to do with the router reaching 100% cpu util. And what have you captured to see if the packets are indeed getting flooded? I will ask again, is there a reason why ip cgmp is enabled on that router's interface?