Proprietary DHCP to ISC DHCP
Simon Hobson
dhcp1 at thehobsons.co.uk
Wed Nov 14 07:41:33 UTC 2007
Keith wrote:
>The proprietary dhcp system hands IP's out in sequential order starting at
>number 1, whereas Ive always seen ISC's start at the highest IP (eg. .254)
>
>I have setup a new DHCP server version 3.1 and I'd like to cut over to
>this machine.
>
>If an existing modem or client does a DHCPREQUEST to the new server for an
>IP it already has, as this is a new server, the lease file is empty
>so there are no known leases yet in the leases file, how does the server
>handle it?
If the requested address is available then it will be given out - ie
the client will keep it's address provided it asks for it.
>As the highest IP in use is only about x.x.x.118, even if ISC's dhcp sends
>back an OFFER starting at .254 it wont be an issue with conflicts, which
>is my primary concern.
This "starting from the top" is undocumented and liable to change at
any time without notice - it is purely an artifact of the way the
tables are managed internally that results in the free address list
being in reverse order. But once all addresses have been used at
least once, then the order is determined by the time since each lease
expired (least recently used first).
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