igmpv2 on a router

[sarahr202]

  Hi everybody

Please consider the following example.

R1---f0/0-----------Sw----------H1

H1 is already configured for igmp goup 224.7.7.7

How can I configure igmpv2 on R1 so R1 can start sending general query on  f0/0?

Thanks and  have a great day.                

[Peter Paluch · Accepted solution]

Hi Sarah,

There is no command on Cisco routers to enable IGMP alone. In order to have R1 start sending IGMP queries on fa0/0, you have to configure PIM on this interface - either Sparse or Dense mode, e.g.:

ip multicast-routing

!

interface FastEthernet0/0

ip pim dense-mode

end

There is another option, though - if the switch in the middle supports the IGMP Querier feature then you can configure this switch to start sending IGMP queries itself on behalf of the router. This is used in situations where you want to use the IGMP Snooping on the switch but have no router that would send the IGMP Queries. In this case, the IGMP Querier configured on the switch steps in by sending queries and eliciting membership reports from hosts, allowing IGMP Snooping to learn about subscribed multicast groups.

You may be interested more about the feature here:

http://www.cisco.com/en/US/docs/switches/lan/catalyst3560/software/release/15.0_2_se/configuration/guide/swigmp.html

Best regards,

Peter