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

[Joann Deng]

Yes, that's correct, both servers are on the same
VLAN. So theoretically, no layer 3 should be involved.


Joann 
--- "Arie Vayner (avayner)" <avayner at cisco.com> wrote:

> 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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