RE: [PATCH][RFC] net/bridge: add basic VEPA support

Subject: Re: [PATCH][RFC] net/bridge: add basic VEPA support

On Tuesday 11 August 2009, Paul Congdon (UC Davis) wrote:

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The patch from Eric Biederman to allow macvlan to bridge between
its slave ports is at

http://kerneltrap.org/mailarchive/linux-netdev/2009/3/9/5125774

Looking through the discussions here, it does not seem as if a

decision

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was made to integrate those patches, because they would make the
macvlan interface behave too much like a bridge.

Right, that question is still open, and dont't see it as very important
right now, as long as we can still use it for VEPA.

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Also, it seems as if there was still a problem with doing
multicast/broadcast delivery when enabling local VM-to-VM
communication. Is that solved by now?

Not yet, but I guess it comes as a natural extension when I fix
multicast/broadcast delivery from the reflective relay for VEPA.

The logic that I would use there is:

broadcast from a dowstream port:
     if (bridge_mode(source_port)) {
          forward_to_upstream(frame);
          for_each_downstream(port) {
                /* deliver to all bridge ports except self, do
                   not deliver to any VEPA port. */
                if (bridge_mode(port) && port != source_port) {
                       forward_to_downstream(frame, port);
                }
          }
     } else {
          forward_to_upstream(frame);
     }


broadcast from the upstream port
     if (bridge_mode(frame.source)) {
          /* comes from a port in bridge mode, so has already been
             delivered to all other bridge ports */
          for_each_downstream(port) {
                if (!bridge_mode(port)) {
                         forward_to_downstream(frame, port);
                }
          }
     } else if (vepa_mode(frame.source)) {
          /* comes from VEPA port, so need to deliver to all
             bridge and all vepa ports except self */
          for_each_downstream(port) {
                if (port != frame.source)
                       forward_to_downstream(frame, port);
     } else {
          /* external source, so flood to everyone */
          for_each_downstream(port) {
                forward_to_downstream(frame, port);
     }

For multicast, we can do the same, or optionally add a per-port filter
as you mentioned, if it becomes a bottleneck.

Do you think this addresses the problem, or did I miss something
important?

Yes, I think this addresses the problem. It would be very useful if
this functionality was in macvlan.

Thanks,
Anna