Join-group over static-oif

Routing & Switching Multicast
1

Good day

I’m not understanding the difference between the command:

ip igmp static-oif

and

ip igmp join-group

isn’t these commands similar? the first command binds a group to the OIF whil the 2nd command binds interface to a group. Isn’t that the same thing? I have looked these up in the Cisco command guide but doesn’t really help. How and when would you use one over the other? To me they sound the same and looks like it just preference on which one you want to use.

Thank you in advance!!

Warren

2

Hello Warren

Just a clarification here. The command ip igmp static-oif is a command found on Nexus devices. The corresponding command on IOS devices is ip igmp static-group.

Now what’s the difference?

  • ip igmp join-group will cause the interface to actively join a multicast group as a member. That means that the IP address of the interface itself is a receiver of that multicast traffic. The result is an entry in the multicast routing table. The interface is also able to ping the multicast group it has joined.
  • ip igmp static-oif (or ip igmp static-group in IOS) will cause the interface to enable hardware switching (or fast switching) of that specific group’s traffic without joining the multicast group itself. The result is that the entry appears in the multicast routing table as before, however, you will be unable to ping the multicast group from that interface, since it is not a member.

I hope this has been helpful!

Laz

3

I think I answered my own question… so the reason why you would prefer the

ip igmp static-oif

over the

ip igmp join-group

is that the first command the traffic generated is handled by the hardware where the second command is handled by the CPU and if your CPU cannot handle all the traffic generated then you introduce other problems. So that is why it is better to use ip igmp static-oif

1 Like