Subject: Re: [Roll] [homenet] Homenet Architecture & Interim Meeting

From: Michael Richardson <[email-masked]>
Date: Fri, 07 Oct 2011 18:38:19 -0400

This is a conversation that started on the Homenet list.

    > So there may also be a requirement for interconnection of
    > multiple ultra-short range networks via a house backbone:
    > e.g. lights on top floor pool to form a mesh network, and lights
    > in the basement form a mesh network, but the reinforced concrete
    > floor partitions the two wireless meshes, so you need a routed
    > connection between them.

    Jari> I think we do include that already. Its part of being able to
    Jari> provide a routed, multi-subnet network. Precisely for these
    Jari> reasons. (But if you are arguing that we should all use some

If you plug two RPL root bridges into two ports of an ethernet switch,
they will happily link your lighting network together.

That's something that I think that might not have been clearly stated in
the discussion at today's interim meeting:  RPL might not be hidden
behind the ethernet/802.15.4 router, it might use the ethernet to
connect different zones.   So, don't be surprised if you see RPL ICMPv6
messages crossing some of the inside lans.

Continuing along the thought process that stuff should just work,
regardless of how grandma plugs things in... it would therefore be nice
if RPL could bridge across a routed homenet lan.

This would work, I think, if the RPL ICMPv6 DIOs, which are currently
multicast to a link-local group by default, could instead on a RPL node
with an uplink, send to a site-local ULA multicast group.  

This is also not strictly necessary: the upstairs and downstairs RPL
meshes, if they allocate ULA prefixes as we have discussed, simply route
across the homenet LAN, and probably things will work.

Where this might fail is if the P2P mechanism in RPL was being used,
because it basically forms a temporary DAG across the mesh find the most
direct route.  If the best route is via the homenet, it won't be found
if the two meshes are partitioned.

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