On Fri, 26 Feb 2010 23:35:15 +0800
Herbert Xu [off-list ref] wrote:

bridge: Add multicast_router sysfs entries

This patch allows the user to forcibly enable/disable ports as
having multicast routers attached.  A port with a multicast router
will receive all multicast traffic.

The value 0 disables it completely.  The default is 1 which lets
the system automatically detect the presence of routers (currently
this is limited to picking up queries), and 2 means that the port
will always receive all multicast traffic.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

I like the functionality, but don't like users whacking on sysfs
directly. Could you send patches to integrate a user API into
bridge-utils; the utils are at: 
  git://git.kernel.org/pub/scm/linux/kernel/git/shemminger/bridge-utils.git