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To: dhcp-v4@bucknell.edu
Cc: brian@awfulhak.demon.co.uk, hackers@freebsd.org
Subject: Q about draft-ietf-dhc-dhcp-09.txt
From: Akihiro Tominaga <tomy@gunpowder.Stanford.EDU>
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Date: Fri, 17 Jan 1997 22:57:10 -0800
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I sent this mail to wrong address, I'm sending again.

==
I want to discuss about the following paragraph (on pg 32);

   o DHCPREQUEST generated during INIT-REBOOT state:

        <omit>

     If the network is correct, then the DHCP server should check if the
     client's notion of its IP address is correct. If not, then the
     server SHOULD send a DHCPNAK message to the client. If the DHCP
     server has no record of this client, then it MUST remain silent,
     and MAY output a warning to the network administrator. This
     behavior is necessary for peaceful coexistence of non-communicating
     DHCP servers on the same wire.


Please think about the following situation.

  A client requests address 'A'.
  There is a server 'X' which has the binding that points address 'B'.
     'B' is already expired.
  There is another server 'Y' which has the binding that points address 
'A'.
     'A' is valid.

This is not illegal situation.  And if 'X' sends NAK and 'Y' sends
ACK, there is no guarantee which packet arrives first.  So the behavior
of the most client depends on arrivals of packets.

IMHO, the server should send back NAK only if the DHCPREQUEST is
directly sent to the specific unicast IP address of the server.  And
in this situation, the server shouldn't send NAK.

Any comment?

--
Visiting Researcher of Stanford Univ.
Mosquito Net Project.
Keio Univ.
WIDE Project.
			Akihiro Tominaga (tomy@mosquitonet.stanford.edu)