log line question

Simon Hobson dhcp1 at thehobsons.co.uk
Mon Dec 13 17:30:08 UTC 2010

Bruce Hudson wrote:

>What I recall was that the basic process
>involved (1) the client broadcast a DISCOVER, (2) potentially multiple
>servers OFFERed, (3) the client selected an offer by some unspecified
>mechanism and broadcast a REQUEST, including the server identifier of
>the server is chose, and (4) only that server ACKed (or NAKed) the

If you put the client to sleep, unplug it's network cable, or 
whatever - when it comes back up on the network it is not supposed to 
use it's existing lease without checking to see it's still valid (you 
may have plugged it into another network).

So the client, if it has persistent storage and an unexpired lease, 
should broadcast a request for the address it wants to use. If it's 
on a different network with a DHCP server, the other server then has 
the opportunity to NACK the request - and then the client can discard 
the lease, and go back to step 1 and broadcast a discover.

Having said that, I've just checked, and my Mac doesn't include 
option 54 (Server Identifier) either when bringing up an interface or 
when forcing a renewal through the Network settings control panel. 
Looking through the server logs, it looks like it's only sent (by 
Macs) at step 3 above.

My DHCP Handbook is at work so I can't look that up right now.

Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
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