[c-nsp] FWSM blocking multicast traffic between two hosts in sameVlan?

[Arie Vayner (avayner)]

Joann,

Just to be sure I get you right, both servers are on the same VLAN
behind the FWSM, and the FWSM is not really part of the multicast stream
(it does not have to pass through it). Is that right?

If this is the case, then the FWSM should not affect the multicast
stream as both servers are on the same VLAN, and multicast is handled by
the L2 mechanism on the 6500.

When you try to "ping <mcast grp>" - I am not fully sure how would this
be sent by the host... I would recommend putting a sniffer on both hosts
and making sure the traffic is sent and received correctly.

Take a look at IGMP snooping:
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/122sx/swcg/s
nooigmp.htm

It could be that you would have to disable it on these ports (depends on
how the applications behave).

Arie Vayner

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Joann Deng
Sent: Saturday, September 01, 2007 00:22 AM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] FWSM blocking multicast traffic between two hosts in
sameVlan?

Hi,

We have hosts in the same Vlan, which connects to FWSM (routed mode).
These two hosts run WebLogic, which uses multicast address 237.155.155.2
to communicate.
But somehow, when run "ping 237.155.155.2" on one host, cannot see
response back from the other.
So, is it possible that FWSM is doing something fancy, like blocking
multicast traffic, and we need to add some configs?
Any input is highly appreciated.

Thanks,

Joann


       
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