DHCP server policy

Mirkin Michael-MMIRKIN1 MichaelMirkin at motorola.com
Thu Jun 8 16:46:41 UTC 2006

Thank you it answer my question and it is more or less what I understood
from documentation.
I use ISC DHCP server/client under MontaVista Linux and I need to
investigate the way to 
enforce random selection of IP address by DHCP server based on clients
MAC address (some
thing like in RFC 3927). Can you advice me where implemented IP
selection in the code of 
DHCP server?

        Michael Mirkin

-----Original Message-----
From: dhcp-users-bounce at isc.org [mailto:dhcp-users-bounce at isc.org] On
Behalf Of Glenn Satchell
Sent: Thursday, June 08, 2006 7:34 PM
To: dhcp-users at isc.org
Subject: Re: DHCP server policy

>Subject: DHCP server policy
>Date: Thu, 8 Jun 2006 19:16:44 +0300
>From: "Mirkin Michael-MMIRKIN1" <MichaelMirkin at motorola.com>
>To: <dhcp-users at isc.org>
>Do you know how DHCP server select IP address for a client?
>Does it work like FIFO, LIFO, round robbing or randomly?
>I need to enforce DHCP server to select IP address for a client as 
>random function of client's MAC address. Does it possible with ISC DHCP

>        Michael Mirkin
The server will initially allocate addresses starting at the highest
address in the range and working down.

Once a client has been allocated an address the server remembers this
and will allocate the same address next time the client requests it, if
it is still available.

The key for this is the client identifier. If this is not set in the
client request then the mac address is used. Typically only Windows dhcp
clients set the client identifier.

This is only a problem where, for example the same client can boot
multipl eoperating systems, or perhaps PXE or similar. If it uses a
client identifier in one environment but not another then the dhcp
server will think of it as two different clients. There has been quite a
bit of ongoing discussion about whther this is desirable behaviour.

Does this answer your question? If not pehaps you could describe what
problem you are trying to get around.


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