Re: [MacVLAN] failure to deliver reassembled IPv6 multicast traffic

[Eric Dumazet <eric.dumazet@gmail.com>]

On Fri, 2013-02-15 at 18:00 +0100, Erik Hugne wrote:
> If macvlan's are configured on a device, IPv6 multicast
> traffic received on the underlying ethernet device is not
> delivered properly to higher layers. Large amounts of packets are lost, and
> the problem seems to get worse the more macvlans are defined
> on top of the device, up to the point where no traffic is delivered
> at all...
> 
> 
> Steps to reproduce (2 hosts required)
> On host 1, set up some macvlans:
> ip link add link eth0 name macvlan0 type macvlan mode bridge
> ip link add link eth0 name macvlan2 type macvlan mode bridge
> ip link add link eth0 name macvlan3 type macvlan mode bridge
> ip link set link dev macvlan0 up
> ip link set link dev macvlan2 up
> ip link set link dev macvlan3 up
> 
> Start a server that binds to ff02::1 scoped to eth0
> ./server6 -sff02::1 -eeth0
> 
> 
> On host 2:
> ./client6 -dff02::1 -eeth0
> 
> 
> This seems to only occur for large (fragmented) IPv6 multicast traffic.
> If you bind to :: instead (-s:: on the server) and send to
> the linklocal address of Host1/eth0, packets are delivered just fine.
> 
> Source for client6/server6 on github:
> git clone git@github.com:Hugne/udp_mc.git

I guess we need to defrag before doing the broadcast,
as we did for IPv4 in commit bc416d9768aa9a2e4
(macvlan: handle fragmented multicast frames)