Friday, May 14, 2010

Internet Addressing - making a hash of it several times

Dear Sir, Lord, Reverend, Almighty Internet,

I've been wondering how you should be addressed.

The powers that be (wise old men) say we should have 128 bits of stuff
allocated either geographically or topologically, or organisationally (provider centric)

I say we should declare IPv6 Bloomsday and have three hash functions and addresses should be allocated with fields set from all three types, by doin a cryptohash of the ID of a node (sim or mac) ...

So the new type of address is the bitwise inclusive OR of the results of all three hash functions:
Hg(id) v Ht(id) v Ho(id)

The properties of this are neat - a router can decide to apply a match on any one of the three hashes, so if a node moves, we can see whether geo, topo, or provider based routing will cope with the migration best - we can also NAT or re-assign permanentally for a node, any 2 of the hashes, and still get a match - provided we dont change all three (or the id)...

This ought to work fairly well, since most nodes execute Levy flights over the net (returning to the nest at end of day, trip, vacation)....

2 comments:

Simon Leinen said...

Lovely! But wouldn't it be hard to make sure there are no loops when different routers use filters derived from different hierarchies? Anyway. The music wasn't long enough for me to think this through properly.

jon crowcroft said...

good comment - ok - so we'd need to make sure the different hierarchies were only used in a "valley free" sequence - this might make sense since the topographic one would be edgemost, the topological one intermedate and the provider one "core" in some sense, so it might look a lot like AS paths in BGP in terms of provider/subscriber path relationships being valley free...maybe - needs some thought

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