Linux Ethernet Bridging - Apr 2007 - [Bridge] Re: 2.6.8 bridging with large packets question

On Thu, 10 Mar 2005 17:46:02 -0800
Ted Deppner <ted@psyber.com> wrote:
> I've got a multicast video application where I'm using a bridge to
get
> duplicated multicast output on each of two physical interfaces.
> 
> eg br0 -> eth0 & eth1.  
> ifconfig br0 x.x.x.x
> route add -net 224.0.0.0/4 br0
> 
> This works perfectly for standard 1500 byte data packets (meaning they
> don't need to fragment).  However, if I use 4096 byte data packets,
which
> obviously must fragment to go on the ethernet, then the packets only go
> out the last interface in the bridge, ie eth1.  There's no packets
going
> out eth0.
Bridging implements a IEEE 802.2 bridge.  This means it is protocol independent,
it doesn't know what a IP packet is.  It's the standard, this is the
correct
behaviour.
> Can you comment on this?  Has this been resolved in a later version of the
> kernel, or is there an option I can tweak?
You could use ebtables (netfilter for bridging), to process data and fragment
as needed.
> Thank you.
> 
> -- 
> Ted Deppner
> http://www.deppner.us/