[syslinux] Client machine cannot acquire the IP from dhcp server

[Geert Stappers]

Op 15-06-2007 om 18:14 schreef Eric Zhang:
> Gilles Espinasse wrote:
> > ----- Original Message ----- 
> > From: "Eric Zhang" <maillistbox at 126.com>
> > Sent: Friday, June 15, 2007 7:22 AM
> > 
> > 
> >> Hi, syslinux:
> >>
> >>     The first time, the client machine can acquire the IP address from
> >> dhcp server but at the second time, the client machine cannot acquire
> >> the IP again.
> >>
> >>     I have tried to run dhcp like this: dhcpd -d, it will print out some
> >> debug info, I found the first time the client machine sent a
> >> DHCPDISCOVER msg and server responsed the DHCPOFFER, then the client
> >> sent a DHCPREQUEST and the server reponsed DHCPACK. But the second time,
> >> the dhcpd didn't print anything out?! Why?
> >>
> > Which dhcp server version?
>
> Hi, Gilles:
> 
>      My DHCP Server version is: dhcp-3.0.1-58.EL4(CentOS 4.4 OS)
> 
>      My /etc/dhcpd.conf:
> 
> ======================================================================================
> allow booting;
> ddns-update-style none;
> option domain-name "jointforce.com.cn";
> option subnet-mask 255.255.255.0;
> option broadcast-address 192.168.0.255;
> option domain-name-servers 218.2.135.1;
> option routers 192.168.0.254;
> subnet 192.168.0.0 netmask 255.255.255.0 {
>    range 192.168.0.1 192.168.0.64;
>    next-server 192.168.0.254;
>    filename "pxelinux.0";
> }
> ====================================================================

> > What time duration for lease renewal is defined?

That question is still unanswered. ( Replying below the question more
advantages then a good readable mailinglist archive )

The manual of the ISC DHCP server has this example:

            subnet 239.252.197.0 netmask 255.255.255.0 {
              range 239.252.197.10 239.252.197.107;
              default-lease-time 600;
              max-lease-time 7200;
            }


My advice is to play with the lease-time options.

Back to the original posting:

> >> I found the first time the client machine sent a
> >> DHCPDISCOVER msg and server responsed the DHCPOFFER, then the client
> >> sent a DHCPREQUEST and the server reponsed DHCPACK. But the second time,
> >> the dhcpd didn't print anything out?! Why?

What is the second time the client does talk to the DHCP server?

And what states that the DHCP server does get the second message
from the DHCP client?

Those are two seperate questions ( please answer both seperately ).
The second question is the important one, it implies an 'are you sure
that the client was actual able to send out the "second" request?'


Hope this Helps
Geert Stappers