Re: [lwip-devel] Using DHCP & AutoIP as connections change

[Sprow]

In article <address@hidden>,
   Bill Auerbach <address@hidden> wrote:
> With DHCP how can I reuse IP addresses on link disconnects but not reuse
> addresses on physical connection changes?
>
> If I call dhcp_stop when the cable is disconnected and dhcp_start when it's
> connected, I get a different IP address each time this happens.  This is 
> not good if the connection glitches.

Isn't it more appropriate to do a dhcp_rebind in this case?
If the netif is still alive, but the link is down (unplugged cable), the
lease is still valid from the DHCP server's point of view since it doesn't
know that the link is down - the rebind is just a courtesy to check that
(for example) the DHCP server hasn't been rebooted in between.

On the DHCP server at work you almost always get the same IP address back,
even if the cable is unplugged for days, which suggests the DHCP server
remembers the MAC address or maybe we just don't end up reusing addresses
much (netmask FFFF0000, only about 180 DHCP clients),
Sprow.