[Bridge] Multicasting and Bridged networking issue

[Bridge] Multicasting and Bridged networking issue

[Singh, Animesh]

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Hi,
    Have been experimenting with bridged networking in order to connect VMs located on separate physical machines. Unicast communication works fine but multicast traffic in not being forwarded beyond the bridge. Looking at the code am reaching the conclusion that bridge treats multicast traffic in same way as broadcast, so why the multicast traffic is not flowing beyond the bridge. Also does kernel tunable like mc_forwarding have any significance in this matter? On the later version of linux 2.6.18 and after am finding this tunable as read-only (and set to 0). The kernel being used has CONFIG_IP_MROUTE enabled but its not running mrouted.


Regards Animesh

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Re: [Bridge] Multicasting and Bridged networking issue

[Stephen Hemminger]

On Tue, 1 Jun 2010 15:08:19 +0530
"Singh, Animesh" <Animesh.Singh@lsi.com> wrote:

> Hi,
>     Have been experimenting with bridged networking in order to connect VMs located on separate physical machines. Unicast communication works fine but multicast traffic in not being forwarded beyond the bridge. Looking at the code am reaching the conclusion that bridge treats multicast traffic in same way as broadcast, so why the multicast traffic is not flowing beyond the bridge. Also does kernel tunable like mc_forwarding have any significance in this matter? On the later version of linux 2.6.18 and after am finding this tunable as read-only (and set to 0). The kernel being used has CONFIG_IP_MROUTE enabled but its not running mrouted.
> 

Are you using VMware? VMware doesn't really allow for bridging.

Re: [Bridge] Multicasting and Bridged networking issue

[Singh, Animesh]

Not really ... we are based atop Xen-3.4.1 with linux-2.6.18 series in Dom0

-----Original Message-----
From: Stephen Hemminger [mailto:shemminger@linux-foundation.org] 
Sent: Tuesday, June 01, 2010 9:45 PM
To: Singh, Animesh
Cc: bridge@osdl.org
Subject: Re: [Bridge] Multicasting and Bridged networking issue

On Tue, 1 Jun 2010 15:08:19 +0530
"Singh, Animesh" <Animesh.Singh@lsi.com> wrote:

> Hi,
>     Have been experimenting with bridged networking in order to connect VMs located on separate physical machines. Unicast communication works fine but multicast traffic in not being forwarded beyond the bridge. Looking at the code am reaching the conclusion that bridge treats multicast traffic in same way as broadcast, so why the multicast traffic is not flowing beyond the bridge. Also does kernel tunable like mc_forwarding have any significance in this matter? On the later version of linux 2.6.18 and after am finding this tunable as read-only (and set to 0). The kernel being used has CONFIG_IP_MROUTE enabled but its not running mrouted.
> 

Are you using VMware? VMware doesn't really allow for bridging.