Re: [Roll] [Bier] Source-Routed Multicast

Carsten Bormann <> Tue, 04 November 2014 22:52 UTC

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From: Carsten Bormann <>
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Date: Tue, 04 Nov 2014 23:50:50 +0100
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To: IJsbrand Wijnands <>
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Subject: Re: [Roll] [Bier] Source-Routed Multicast
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> Just one clarification, BIER is not Source-Routed multicast. i.e. we don’t include a list of hops that the packet needs to follow, we only include final destination in the form of Bit Positions, and each router along the path does a lookup on the Bit Position to determine where the packet is to be sent.

Indeed, that’s why I titled this E-mail “Source-Routed Multicast” so it is clear it is not the same as BIER.  Source-routing is important for RPL’s non-storing mode, where intermediate routers just don’t know what is below them.  (BIER could be applied to RPL’s storing mode, but then that already has a multicast approach written up, and it’s also not that clear that storing mode actually exists.  The next question would then be whether RPL networks are stable enough to have a stable egress router numbering applied to them.)

It seems several people would be able to make a Sunday hallway chat about this general approach.  Since I’m officially at a couple of meetings (in parallel) from 1600, how about 1500?

Grüße, Carsten