[v4,0/5] Implementation of a Stateless Multicast Packet Type

Message ID	20221227193409.13461-1-linus.luessing@c0d3.blue
Headers	show Return-Path: <b.a.t.m.a.n-bounces@lists.open-mesh.org> From: =?utf-8?q?Linus_L=C3=BCssing?= <linus.luessing@c0d3.blue> To: b.a.t.m.a.n@lists.open-mesh.org Subject: [PATCH v4 0/5] Implementation of a Stateless Multicast Packet Type Date: Tue, 27 Dec 2022 20:34:04 +0100 Message-Id: <20221227193409.13461-1-linus.luessing@c0d3.blue> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Message-ID-Hash: OO74FAVSGPSIHNU6D6ZCEF2UJ35O667L Precedence: list Reply-To: The list for a Better Approach To Mobile Ad-hoc Networking <b.a.t.m.a.n@lists.open-mesh.org> Archived-At: <https://lists.open-mesh.org/mailman3/hyperkitty/list/b.a.t.m.a.n@lists.open-mesh.org/message/OO74FAVSGPSIHNU6D6ZCEF2UJ35O667L/>
Series	Implementation of a Stateless Multicast Packet Type \| expand [v4,0/5] Implementation of a Stateless Multicast Packet Type [v4,1/5] batman-adv: mcast: remove now redundant single ucast forwarding [v4,2/5] batman-adv: tvlv: prepare for tvlv enabled multicast packet type [v4,3/5] batman-adv: mcast: implement multicast packet reception and forwarding [v4,4/5] batman-adv: mcast: implement multicast packet generation [v4,5/5] batman-adv: mcast: shrink tracker packet after scrubbing

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20221227193409.13461-1-linus.luessing@c0d3.blue

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From: =?utf-8?q?Linus_L=C3=BCssing?= <linus.luessing@c0d3.blue>
To: b.a.t.m.a.n@lists.open-mesh.org
Subject: [PATCH v4 0/5] Implementation of a Stateless Multicast Packet Type
Date: Tue, 27 Dec 2022 20:34:04 +0100
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Series

Implementation of a Stateless Multicast Packet Type | expand

Message

Linus Lüssing Dec. 27, 2022, 7:34 p.m. UTC

Hi,

The following patchset implements a stateless, TVLV capable batman-adv
multicast packet type.

The new batman-adv multicast packet type allows to contain several
originator destination MAC addresses within a TVLV. Routers on the way will
potentially split the batman-adv multicast packet and adjust its tracker
TVLV contents.

Routing decisions are still based on the selected BATMAN IV or BATMAN V
routing algorithm. So this new batman-adv multicast packet type retains
the same loop-free properties.

The purpose of this new packet type is to allow to forward an IP
multicast packet with less transmissions / overhead than the
multicast-via-multiple-unicasts approach. Or to reach a lot more
destinations (currently up to 196, depending on the payload size, see
Wiki documentation for details) than with the default multicast fanout
for the via-unicasts approach.

This will allow using applications like mDNS again in several Freifunk
communities. And with less transmissions will also make more bulky
multicast applications, like media streaming (to an assessable amount of
receivers) a lot more feasible.

This approach is way simpler than the original multicast (tracker) packet
approach we envisioned years ago. As it involves no maintenance of an
extra, state based multicast routing table. However the TVLV capability
should allow to extend things later, to split control and data plane a bit
more for instance, to further increase the number of destinations, to
further reduce overhead.

A compact overview can be found in the Wiki here, including limitations:

https://www.open-mesh.org/projects/batman-adv/wiki/Multicast-Packet-Type

Regards, Linus

Comments

Sven Eckelmann Jan. 27, 2023, 9:26 a.m. UTC | #1

On Tuesday, 27 December 2022 20:34:04 CET Linus Lüssing wrote:
[...]
> The purpose of this new packet type is to allow to forward an IP
> multicast packet with less transmissions / overhead than the
> multicast-via-multiple-unicasts approach. Or to reach a lot more
> destinations (currently up to 196, depending on the payload size, see
> Wiki documentation for details) than with the default multicast fanout
> for the via-unicasts approach.

Please don't forget that batctl's tcpdump also requires support for parsing 
it.

Kind regards,
	Sven