Multicast for cluster heartbeat messages [RED HAT LINUX]

[Ravindra Simpi]

We are setting up a server using two RED HAT LINUX nodes (Redhat-A and Redhat-B). Redundancy and cluster has been configured on these nodes. Both the nodes are connected to a redundant pair of 7606 routers (R-A and R-B). both R-A and R-B are connected through a dot1q trunk. ( Please see attachment )

Redhat requirement for cluster needs IGMP snooping to be disabled for cluster messages to get exchanged.

I understand that disabling IGMP snooping will flood multicast packets on all ports in the VLAN. My question is, what about trunk? when this multicast packet is sent over trunk, will the other router just flood it within VLAN or will it flood it on all the vlans that are allowed over trunk?

[Jon Marshall · Accepted solution]

It should only flood it within the vlan that the servers are in.

One thing i did notice is that you have PIM enabled on the vlan interface. What is this for ?

Jon

[Ravindra Simpi]

Yes, that is another thing I wanted to know. As cluster heartbeat multicast messages are exchanged between servers that are within same VLAN, I feel PIM and 'ip multicast-routing' are not required.

Am I right?

[Jon Marshall]

If you only need multicast within that vlan then you do not need PIM enabled because as you say that is used to route multicast traffic between vlans.

Jon

[Ruben Cocheno]

all the traffic remains in the same L2 domain, i don't need a PIM interface or activate multicast i guess. I remember in old days Microsoft NLS where you need configure static multicast entries

http://www.cisco.com/c/en/us/support/docs/switches/catalyst-6500-series-switches/68131-cat-multicast-prob.html

you can disable igmp snooping per interface basis, under the interface. If not you will have a big flood and probably slow performance across all interfaces

[Jon Marshall]

you can disable igmp snooping per interface basis, under the interface

which switches support disabling IGMP snooping per interface ?

Jon

[Ruben Cocheno]

i didn't test but i believe this is accurate

Enabling IGMP Snooping

http://www.cisco.com/c/en/us/td/docs/routers/7600/ios/15S/configuration/guide/7600_15_0s_book/snooigmp.html#wp1027812

[Jon Marshall]

Okay, i think we may be talking about slightly different things.

You can disable it on a L3 vlan interface but within a vlan i'm not aware of being able to disable it on physical ports.

So as the multicast will be limited to the vlan anyway (as long as you don't route it)  i don't think you can then specify which ports within that vlan run IGMP snooping and which don't ie. IGMP snooping is global per vlan.

Jon