Re: [Mcast-wifi] "MLDv2 Procedures for Link-Layer Unicast Delivery of Multicast IPv6"

Linus Lüssing <linus.luessing@c0d3.blue> Wed, 09 December 2015 17:03 UTC

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Date: Wed, 9 Dec 2015 18:01:16 +0100
From: Linus =?utf-8?Q?L=C3=BCssing?= <linus.luessing@c0d3.blue>
To: Mark Smith <markzzzsmith@gmail.com>
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Subject: Re: [Mcast-wifi] "MLDv2 Procedures for Link-Layer Unicast Delivery of Multicast IPv6"
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Hi Mark,

Just wanted to drop a note that not that long ago OpenWRT, a
Linux distribution for embedded devices (esp. wireless routers),
got a multicast-to-unicast feature.

It utilizes the Linux bridge and its multicast snooping
capabilities. OpenWRT's network manager "netifd" configures
everything in a way, that one STA using MLDv1 cannot shadow
another STA through report suppression: All traffic will hit the
bridge sitting on top of the AP interface by enabling
"AP isolation", STA-to-STA communication is reenabled again by
the bridge reflecting packets back on the incoming port (the
"hairpin mode" of the Linux bridge).

All in all it is not really a "beatiful" solution, but at least
using the bridge is a simple one.


Thanks for your efforts regarding this topic! Something like this
is really needed to make multicast streaming over 802.11
possible.

Regards,
Linus


PS: I would be interested in the feedback you got too, for
instance to know whether something should be changed/improved in
what OpenWRT currently does :).

PPS: The multicast-to-unicast patch for the Linux bridge in
OpenWRT is not upstream in the vanilla kernel yet. But hopefully
it will be proposed to the Linux bridge mailinglist soon(tm).