On Don, 2008-12-11 at 21:29 +0100, Juliusz Chroboczek wrote:
> Dear all,
> 
> I'm currently in the process of redesigning AHCP[1], so I thought I'd share
> a number of ideas with you.
>
> AHCP is an address configuration protocol.  Because it is designed for mesh
> networks, it needs to solve a number of issues that are not handled by DHCP:

I also don't want to troll but I read too much IMHO not quite correct details:

>   - it needs to work across multiple hops;

DHCP also works through multiple hops - one uses DHCP-Relayers for that.
Of course one has to configure all that - but you have to configure DHCP
in any case.
And if that concept of a "relayer" is convenient or elegant, are other
questions.

>   - a part of the network needs to be able to survive for at least a few
>     hours when it becomes isolated from the rest of the network;

That gets IMHO really interesting if the parts join again and detect
IP-address clashes because two new nodes in different networks got the
same one.
Yes, that might be quite improbable with IPv6 + true random numbers -
but it will be possible (and thus happen sooner or later) so the
protocol must handle that.

>   - stale configuration data needs to be reliably flushed from the network
>     even when connectivity is lost;
>   - it needs to work when time synchronisation is lost, both on clients and
>     on servers.

DHCP doesn't need sync'd clocks at all (simply because at the time of
the design/development of DHCP, clock synchronization was far from
"normal" IMHO).
That's the reason why DHCP has no absolute timestamps in the protocol -
just time duration like "lease time".
So it's just a question of how much jitter do the clocks have (and the
difference is meaningless).

Of course AHCP (and other protocols) have to deal with the situations
described above but some are IMHO "handled" by DHCP today.
And if it's better (because e.g. the net of LANs of mega-corporations
spread over the world and connected by WAN links survive the local power
outs of a few hours gracefully), people will use it in wired nets too.

[...]
	Bernd
-- 
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