DHCP question: dhclient won't request same IP.

[Thomas Charron]

  I wonder if dhclient or whatever client it's using is crashing, and the
init script is bringing it back up....

On 1/31/07, Dave Johnson <dave-gnhlug at davej.org> wrote:
>
> Scott Garman writes:
> > To test things further, I placed both machines behind a Linux DHCP
> > server so I could look for any unusual error messages. Sure enough, I
> > found the following in my logs after the Debian system exhibited the
> > IP-changing behavior. The Debian system started out with IP
> > 192.168.1.215, and ended up with 192.168.1.210:
> >
> > Jan 31 12:32:03 dhcpd: DHCPDISCOVER from 00:d0:c9:9e:ae:59 via eth1
> > Jan 31 12:32:03 dhcpd: ICMP Echo reply while lease 192.168.1.215 valid.
> > Jan 31 12:32:03 dhcpd: Abandoning IP address 192.168.1.215: pinged
> > before offer
> > Jan 31 12:32:03 dhcpd: Wrote 0 deleted host decls to leases file.
> > Jan 31 12:32:03 dhcpd: Wrote 0 new dynamic host decls to leases file.
> > Jan 31 12:32:03 dhcpd: Wrote 9 leases to leases file.
> > Jan 31 12:32:05 dhcpd: DHCPDISCOVER from 00:d0:c9:9e:ae:59 via eth1
> > Jan 31 12:32:06 dhcpd: DHCPOFFER on 192.168.1.210 to 00:d0:c9:9e:ae:59
> > via eth1
> > Jan 31 12:32:08 dhcpd: DHCPREQUEST for 192.168.1.210 (192.168.1.1) from
> > 00:d0:c9:9e:ae:59 via eth1
> > Jan 31 12:32:08 dhcpd: DHCPACK on 192.168.1.210 to 00:d0:c9:9e:ae:59 via
> > eth1
>
> It appears the client is sending a DHCPDISCOVER while still using the
> old address (the server can ping it).
>
> For a renewal of an existing lease the client should first send a
> DHCPREQUEST instead of DHCPDISCOVER.  Only if the DHCPREQUEST is
> ignored/lost should it send a DHCPDISCOVER in an attempt to find a new
> lease.
>
> The server is doing the right thing in this case.  If the server
> recieved a DHCPREQUEST first it would extend the existing lease.
>
> The logs from the client computer may reveal the requests and if it is
> trying a REQUEST first with no response.
>


-- 
-- Thomas
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