[Olsr-users] Heads-up: AHCP redesign

[Juliusz Chroboczek]

>>   - it needs to work across multiple hops;

> DHCP also works through multiple hops - one uses DHCP-Relayers for that.

You're right.

> Of course one has to configure all that - but you have to configure DHCP
> in any case.

There are actually two ways to get multi-hop DHCP: relays and prefix
delegation.  As you note, DHCP will not automatically set-up relays, you
need to set up one relay per link manually.

Additionally, I don't think DHCP will not forward over the same interface,
which is needed in mesh networks.  However, I'd love to be proved wrong --
if you manage to set up DHCP in a mesh network, please let us know.

>>   - 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.

The idea is that we are sufficiently careful when handling out leases that
clashes don't happen.

> 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).

I'm afraid I don't understand -- as far as I know, a DHCP server must have
a reasonable clock.  Consider a DHCP server that gives out a lease and then
reboots -- unless the lease was committed to stable storage with
a reasonable timestamp, you'll get address conflicts.

In other words, while you are right that time skew between the client and
the server doesn't matter, the server needs to preserve time across reboots.

                                        Juliusz