log line question

Bruce Hudson Bruce.Hudson at Dal.Ca
Mon Dec 13 15:16:04 UTC 2010

>>     It appears to be the DHCP Server Identifier from the request so
>> it should be the IP address of your DHCP server. The server should
>> ignore any that do not match.
> Correct, it is the server identifier - but that doesn't mean the 
> server should ignore it. The server will ignore unicast requests 
> since it won't see them at all - but of the other server is offline 
> then eventually the client will broadcast it's requests - which I 
> think it will also do after waking/starting up/etc.

    I would not expect clients in the REBOOT or REBINDING states to
include a server identifier in their requests; only when SELECTING. 

    Perhaps I need to go back and review the basic DHCP protocols and
see if things have changed. 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

    I suppose the "only" in step 4 may be me reading in things that are
not there. The DHCP Handbook says the server identifier is "to select
the server to which a broadcast DHCP message is directed". It does not
quite say other servers will honour that direction.
Bruce A. Hudson				| Bruce.Hudson at Dal.CA
ITS, Networks and Systems		|
Dalhousie University			|
Halifax, Nova Scotia, Canada		| (902) 494-3405

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