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

Linus Lüssing <> Wed, 09 December 2015 17:03 UTC

Return-Path: <>
Received: from localhost ( []) by (Postfix) with ESMTP id DAD731ACEAA for <>; Wed, 9 Dec 2015 09:03:09 -0800 (PST)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: 2.936
X-Spam-Level: **
X-Spam-Status: No, score=2.936 tagged_above=-999 required=5 tests=[BAYES_50=0.8, FAKE_REPLY_C=1.486, HELO_EQ_DE=0.35, MIME_8BIT_HEADER=0.3] autolearn=no
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id eKojP--rS9JP for <>; Wed, 9 Dec 2015 09:03:08 -0800 (PST)
Received: from ( []) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id CC7AB1ACE93 for <>; Wed, 9 Dec 2015 09:01:26 -0800 (PST)
Received: from (localhost []) by (Postfix) with ESMTP id 5AACF588BBA for <>; Wed, 9 Dec 2015 18:01:23 +0100 (CET)
Received: from localhost (unknown [IPv6:2001:67c:2d50:0:c85:8cff:fe0f:63fe]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by (Postfix) with ESMTPSA id 0CA4E588BB5; Wed, 9 Dec 2015 18:01:21 +0100 (CET)
Date: Wed, 9 Dec 2015 18:01:16 +0100
From: Linus =?utf-8?Q?L=C3=BCssing?= <>
To: Mark Smith <>
Message-ID: <20151209170116.GH10527@otheros>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <>
User-Agent: Mutt/1.5.24 (2015-08-30)
X-GPG-Mailgate: Not encrypted, public key not found
Archived-At: <>
Subject: Re: [Mcast-wifi] "MLDv2 Procedures for Link-Layer Unicast Delivery of Multicast IPv6"
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: "Discussions related to issues with multicast in 802.11 Wi-Fi networks & solutions/optimizations targeted at resolving these issues." <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Wed, 09 Dec 2015 17:03:10 -0000

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


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).