Second DHCP request during boot-time with different IP-request

Roel van der Made r.vandermade at
Tue Dec 18 10:16:30 CET 2007

On Mon, 2007-12-17 at 23:16 +0100, Thomas Lange wrote:
> >>>>> On Mon, 17 Dec 2007 17:17:57 +0100, Roel van der Made <r.vandermade at> said:
>     > - why the second dhcp request since it already received it trough
>     > dhcpd/pxe ?
> This is fine. The first DHCP request comes from you NIC, the second
> from the kernel, which cannot get the ip address from the NIC. But I'm
> wondering why it wants a certain ip address which is also a wrong address.
> Did you specify anything related in your pxelinux.cfg?

I agree but the requesting mac-address is exactly the same, this is my

kernel vmlinuz-2.6.18-5-486
append initrd=initrd.img-2.6.18-5-486 ip=dhcp  root=/dev/nfs
nfsroot=/srv/fai/nfsroot boot=live  FAI_FLAGS=verbose,sshd,createvt

Quite default, it's a mystery to my why it wants the .147 ip address and
only that address so badly. If I boot the second host the requesting
ip-address is .148 so there is something 'logical' going on there, but

>     > - why would go ask for a specific ip-address in the same network and
>     > doesn't it just bind on the earlier supplied ip-address ?
> I don't know. Maybe something weird in your dhcpd.conf. Try with the
> dhcpd.conf example supplied by the fai-doc package.

I would indeed also say it has to do something with the dhcpd server but
I cannot find any possible reason, this is my dhcpd.conf :

deny unknown-clients;
option dhcp-max-message-size 2048;
use-host-decl-names on;
default-lease-time 864000;
max-lease-time 864000;
log-facility local7;

option domain-name "";
option domain-name-servers,;

subnet netmask {

host fai-client1 {
  hardware ethernet 00:0c:29:d6:46:2b;
  fixed-address fai-client1;
  filename "/pxelinux.0";
  server-name "faiserver";

host fai-client2 {
  hardware ethernet 00:0c:29:6e:f5:4e;
  fixed-address fai-client2;
  filename "/pxelinux.0";
  server-name "faiserver";

Resolving works fine, forward and reverse.

Possibly the nics have swapped in order when booting the kernel but
still this doesn't have to be an issue since it can re-use the
previously supplied ip-address.

>     > A different question is, what's the best place to initiate a dhcp-client
>     > request for a second interface, which is actually the interface to be
>     > used for internet-connectivity and thus the bootstrap location.
> Write a hook (for example extrbase.MYCLASS), which calls the
> dhcp-client. But you have to decide when you need the second interface
> and maybe rename the hook so it's called earlier.

Ack, I need it in a very early stage so I will rename it indeed.



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