[Bridge] [PATCH net-next] bridge: multicast to unicast
Johannes Berg
johannes at sipsolutions.net
Wed Jan 11 09:17:58 UTC 2017
> > Exactly. My point is that this is breaking the expectation that
> > hosts are actually able to drop such packets.
>
> [readding CCs I removed earlier]
>
> Ah! Thanks. I was worried about creating packetloss :D.
Ah, well, no - at least not in this case.
> Hm, for this other other way round, I think it does not apply for
> the bridge multicast-to-unicast patch if I'm not misreading the
> bridge code:
>
> For a packet with a link-layer multicast address but a unicast IP
> destination, the bridge MDB lookup will fail.
> (http://lxr.free-electrons.com/source/net/bridge/br_multicast.c?v=4.8
> #L178
> returns NULL)
>
> Case A): No multicast router on port:
> -> bridge, br_multicast_flood(), will drop the packet already
> (no matter if multicast-to-unicast is enabled or not)
>
> Case B): Multicast router present on port:
> -> The new patch does not apply multicast-to-unicast but just floods
> packet unaltered
> ("else { port = rport; addr = NULL; }" branch)
Ah, interesting. This is different then - the mac80211 code is not L3
aware at all.
johannes
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