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

From: Ben Greear <[email-masked]>
Date: Fri, 15 Feb 2013 11:07:12 -0800

On 02/15/2013 09:00 AM, 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.

This has been around for a long time, maybe forever.  Last time
we looked at this it did not appear there was an easy fix, something
to do with how UDP packets are re-assembled....

Thanks,
Ben

-- 
Ben Greear <[email-masked]>
Candela Technologies Inc  http://www.candelatech.com