How to do 'igmp join-group' on SSM igmp v3?

news2010a · ‎09-01-2009

Hi, from a given interface, I attempted to do for testing:

#ip igmp join-group <IP>

and the command was refused stating that can't be done on SSM.

Do you know the command to join-group in SSM then?

Giuseppe Larosa · ‎09-01-2009

Hello Marlon,

you need to use

ip igmp static-group

ip igmp static-group {* | group-address [source {source-address | ssm-map}] | class-map class-map-name}

http://www.cisco.com/en/US/docs/ios/ipmulti/command/reference/imc_03.html#wp1011528

but the device is not a member of (S,G) group to have one router answering to a ping to G with source S you need to put a ip igmp join-group G on a downstream router.

Hope to help

Giuseppe

news2010a · ‎09-01-2009

I did this on the router; I can see it listed on ip mroute now after the manual command. So I proved that I proved that from source to G traffic can flow OK. So can I conclude that the device which is attached to my G4/2 interface is probably the culprint and not joining or issuing multicast requests properly, right?

10.1.62.89, 239.254.12.2), 00:06:37/00:03:26, flags: sT

Incoming interface: GigabitEthernet4/1, RPF nbr 10.1.70.89

Outgoing interface list:

GigabitEthernet4/2, Forward/Sparse, 00:06:37/00:02:47, H

Giuseppe Larosa · ‎09-01-2009

Hello Marlon,

I do agree that in this way you have checked the capability of your network to carry SSM multicast traffic for (S,G) up to port g4/2.

you can use debug ip igmp to see what is happening with the client.

Hope to help

Giuseppe

Peter Paluch · ‎09-01-2009

Hello Marlon,

What is the IOS version you are using? According to the IOS 12.4 Mainline manual, that command should not have any problems with IGMPv3 and the SSM.

Best regards,

Peter

news2010a · ‎09-01-2009

The IOS is 12.4.

Here is my problem:

I have one device (S) which is getting only partial Multicast traffic. Device is connected to a Cisco 2950. Then the 2950 is connected to a 4507 doing layer 3.

I suspect it could be a missing access-control list on the ssm config which is blocking or not allowing traffic, but I am not sure.

I have one device on another site that works properly. So I thought I could gather traffic flow from this 'bad' device and compare against the 'good' one.

That said, do you think debug ip igmp is a better approach, or how about building an access-list to block all traffic from IP=Source and do an input-log so that I will see all traffic the device is trying to hit, right?