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Multicast for cluster heartbeat messages [RED HAT LINUX]

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?

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Hall of Fame Super Blue

It should only flood it

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

7 REPLIES
Hall of Fame Super Blue

It should only flood it

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

New Member

Yes, that is another thing I

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?

Hall of Fame Super Blue

If you only need multicast

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

Bronze

all the traffic remains in

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

Hall of Fame Super Blue

For my own clarification

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

which switches support disabling IGMP snooping per interface ?

Jon

Bronze

i didn't test but i believe

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

Hall of Fame Super Blue

Okay, i think we may be

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

 

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