Multiple leases

Simon Hobson dhcp at
Mon Jun 5 22:07:17 UTC 2006

Eustace, Glen wrote:

>Has anyone found a way of forcing a singled NIC, i.e. a constant MAC
>Address, to be allocated the same lease regardless of any Client Id that
>may be in the DHCP request.
>Whilst opting for this behaviour may be considered broken by some and to
>violate the RFC, I cannot think of any other way to get our PC and MAC
>Labs (PXE and Netboot) to behave in a predicatable way that allows them
>to work as we would like.
>I don't really want to get into hacking code but .....

AFAIK, at the moment that is what you will need to do. There was talk 
of a patch to do this, I don't know what it's status is.

Ways of doing it :

Simply delete the client-id from all incoming packets - crude.

Insert the MAC address into the client-id field if the client-id is 
blank - makes things work the 'windows way' if the client ID is blank

I'm slightly surprised that you have this problem with the Macs 
though. By default neither OS9 nor X send a client-id, and I'd be 
surprised to see the Netboot client using one either. The usual 
problem is Windows which puts the Mac address in the client-id whilst 
nothing else does.


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