Date: Thu, 24 Aug 2006 06:59:11 -0400 From: Pat Lashley <patl+freebsd@volant.org> To: Ian Smith <smithi@nimnet.asn.au> Cc: freebsd-net@freebsd.org, Doug Barton <dougb@freebsd.org>, Fredrik Lindberg <fli+freebsd-net@shapeshifter.se> Subject: Re: Zeroconfig and Multicast DNS Message-ID: <4361C9398E9A195D2FB0B011@garrett.local> In-Reply-To: <Pine.BSF.3.96.1060824160937.11983B-100000@gaia.nimnet.asn.au> References: <Pine.BSF.3.96.1060824160937.11983B-100000@gaia.nimnet.asn.au>
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> I've been watching this thread with great interest, having recently been > introduced to the possibilities of OLSR (net/olsrd) for local (and > beyond) P2P wi-mesh networks, and wondering if/how zeroconf fits in. > > Some refs: My discovery point, a great (online) book found from a review > by Geoff Huston in the Internet Protocol Journal Vol 9 No 2, p44: > > Wireless Networking in the Developing World: http://wndw.net/ > OLSR.ORG: http://www.olsr.org/ > RFC: http://ietf.org/rfc/rfc3626.txt (basis, though olsrd extends this) > > Host addresses in such a MANET appear to require manual allocation so > far, usually in RFC1918 ranges, but the notion of zeroconfig-joining > such a network seems perhaps worthy of exploration? > > Am I way off base here, thinking some matchmaking might be useful? This is all off the top of my head... For a small enough mesh, with low enough latencies, I believe that you could just define the entire mesh as one link, sharing a single instance if the Link Local IP range. Everything acting as a router/bridge would have to propagate the various LLA packets throughout the mesh but avoid sending them off-mesh. OLSP or other ad-hoc routing protocols should handle that setup as well as if every host had a static IP. (I don't remember the details of LLA, but I know that mDNS needs multicast support. So you would need an ad-hoc routing mechanism that supports multicast to get a full zeroconf mesh with DNS and service discovery.) But the design would start to break down as the mesh grows large enough to either use a significant percentage of the LL address range or to make end-to-end latency significant. I can think of a couple of potential approaches to designing a federation of smaller meshes; but they all have some pretty tricky issues to resolve. I strongly suspect that it would be simpler to just build your mesh using IPv6 only; and to provide 6-to-4 (NAT?) conversion at the interfaces between the mesh and the WAN. (The IPv6 address range is large enough that every interface already has a globally unique link-local address; so no need to negotiate, defend, or change the IP addresses as things move around.) Also, I'm not familiar with OLSP; but I note that it apparently actively discovers nodes one and two hops away. It isn't clear to me how it handles routing to anything further than two hops. I also note that there are a mind-boggling number of ad-hoc routing protocols to choose from... -Pat
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