Comment 5 for bug 505916

> clientid_param=${clientid:+"-r $clientid"}
> What I dislike is the inconsistency that the kernel command-line parameter "clientid" is used for udhcpc parameter "Request IP address".

Why do you dislike that?
That was put there intentionally, to allow people with DHCP problems to specify either an empty client id, or PXEClient, or MSFT5.0, or LTSP-i386 or whatever else their specific environment required.
The clientid was later on forced to '' to avoid duplicate leases (one for PXE and one for udhcpc).

I believe that clientid_param should be put to use again, i.e. make clientid="''" by default, but allow it to be overriden by a kernel command line parameter, so that by default we avoid duplicate leases, but people with Windows DHCP servers can set clientid="MSFT5.0" in pxelinux.cfg/default so that they get the same lease as in Windows.