[ale] 2 boxes getting the same address from DHCP

[Brian Pitts]

Jim Kinney wrote:
> Does this persist if the boot up order is swapped? It sort of looks like the
> first machine is becoming a dhcp server and only has a single address to
> give out. Which still makes no sense.
> Why is machine 1 getting more than 1 address? During pxe it gets 145 and
> then during the dhcpcd it gets a second address. I suspect it doesn't
> release the first one. It _should_ get the same one again unless the dhcp
> server has two sections, one for pxe address and a second for dhcp without
> pxe.
> 
> Since dhcp is supposed to hand out the same address within the lease period,
> and it isn't, either the dhcp code is miscompiled, buggy, configured wrong
> or the machine has a ram error.

The problem persists if the boot order is changed. I know both machines
are getting their addresses from the same DHCP server (and not becoming
one themeselves) by watching the leases file on my DHCP server.

I think I understand why the PXE ROM and OS could different addresses.
PXE ROM doesn't send a client-id when it makes its request, but the OS
does. The  DHCP server doesn't assume won't assume they're same. This
raises the question client-id is the OS using? If both machines are
sending the same client-id, that would explain why they end up with the
same address. My interpretation of the manpage is that the -I '' in

dhcpcd -L -n -t 10 -I '' -h sysresccd eth0

should make the client id be the MAC address, so that doesn't explain
things.

-Brian