Re: [B.A.T.M.A.N.] UDP multicast

[Simon Wunderlich <simon.wunderlich@s2003.tu-chemnitz.de>]

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Hello Olivier,

yes, batman advanced (note, not the layer 3 BATMAN) supports multicast. It
behaves like a (rather lossy) Ethernet interface and transports multicast
traffic just like broadcast. For broadcast, we use a "classic flooding"
approach, which means that every message is rebroadcasted by every node
once when heard first. This "works" also for UDP multicast traffic, 
but is not designed for high bandwidth multicast/broadcast data.

Linus and me are working on an optimization for multicast which is currently
in an experimental stage, which may also be better suited for your application.
However, I don't know whether LCM works on lossy networks and which bandwidth
requirements it has. Also note that the optimization is not "deployment ready"
yet. ;)

A few pointers to get started:
Quick Start Guide: http://www.open-mesh.org/wiki/batman-adv/Quick-start-guide
First Announcement of Multicast Optimization (Specification attached):
https://lists.open-mesh.org/pipermail/b.a.t.m.a.n/2010-December/003858.html


best regards,
	Simon

On Thu, Mar 24, 2011 at 07:42:21PM +0000, Toupet, Olivier wrote:
> Hello,
> 
> I am considering using the Lightweight Communications and Marshalling (LCM) library recently developed at MIT: http://code.google.com/p/lcm/ . However, that library relies on UDP multicast and I need it to work for mesh networks. I have only used simple UDP in the past with B.A.T.M.A.N. and I was wondering if my applications would still work with B.A.T.M.A.N. if I went with UDP multicast. Doing a little bit of research on the web seems to indicate that the UDP packets would be treated like broadcast packets and would then be flooded in the network, which doesn't seem efficient bandwidth-wise. Is that really the case? Would B.A.T.M.A.N. work with LCM (i.e. UDP multicast)? Is there documentation that explains how to set up B.A.T.M.A.N. for UDP multicast?
> 
> Thanks in advance for your reply.
> 
> Best regards,
> 
> Olivier

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