DHCP renew before half the lease time

[King, Michael]

Look for the client Identifier.

 If the client is changing that, the server would treat it as a
different client.

-----Original Message-----
From: dhcp-users-bounce at isc.org [mailto:dhcp-users-bounce at isc.org] On
Behalf Of Staffan.Ungsgard at teliasonera.com
Sent: Tuesday, October 24, 2006 7:11 AM
To: dhcp-users at isc.org
Subject: RE: DHCP renew before half the lease time

This is what the log says:

Oct 24 11:52:58 dhcp3 dhcpd: [ID 702911 local0.info] DHCPREQUEST for
xxx.23.3.175 from 00:xx:xx:18:66:23 via hme0: lease xxx.23.3.175
unavailable. 

I have sniffed the traffic and I can see no change whatsoever compared
to a request that works.
The ip-address and MAC are the same as they were, and the same that is
seen in the broadcasted request  some minutes later.

Staffan

-----Original Message-----
From: dhcp-users-bounce at isc.org [mailto:dhcp-users-bounce at isc.org] On
Behalf Of Simon Hobson
Sent: den 24 oktober 2006 13:00
To: dhcp-users at isc.org
Subject: Re: DHCP renew before half the lease time

<Staffan.Ungsgard at teliasonera.com> wrote:
>I have a device which ignores the lease time and sends out requests to 
>get its address renewed long before half the lease time has expired.
>The dhcp server then NAKs the request.

The server should not NAK the request. It is valid for the client to
renew any time it wants to - it might just be that the user has
unplugged and replugged the network cable, or it's woken from sleep, or
... and so the client wants to verify that it's network settings are
still valid.

>One second before half the lease time has expired the client makes a 
>broacast request for the address, and that request is honored.
>Is this the correct behaviour - should the dhcp server NAK requests 
>coming to soon, or should I look for a solution on the problem 
>elsewhere.

You need to be looking at other reasons for the issue. Sniff the packets
(I'm now a fan of Ethereal/Tethereal) and see what is actually in the
exchanges.

Simon