RE: [dhcwg] Computation of T1, T2, and lease expiration time

I think the text you refer to is:

   The client records the lease expiration time as the sum of
   the time at which the original request was sent and the duration of
   the lease from the DHCPACK message.

And, the question is what does "original request" refer to - the
DISCOVER or REQUEST?

To be completely safe, using the DISCOVER would be best (since that will
result in the shortest lease / T1 / T2 times for the client). But, I
think practially speaking that REQUEST is OK.

But, any client and server need to be prepared for some grace period for
leases as there is no requirement that the client and server have
synchronized clocks and their individual clocks may run fast or slow.

Perhaps this would be item to include in a future revision of
draft-ietf-dhc-implementation-01.txt?

- Bernie

-----Original Message-----
From: dhcwg-admin@ietf.org [mailto:dhcwg-admin@ietf.org] On Behalf Of
Kevin A. Noll
Sent: Monday, April 05, 2004 3:01 PM
To: dhcwg@ietf.org
Subject: [dhcwg] Computation of T1, T2, and lease expiration time

Paragraph 2 of Section 4.4.1 of RFC2131 implies that T1, 
T2, and the lease expiration time are all computed relative 
to the time that the client sends the DHCPDISCOVER.

Is this correct, or should these values be computed relative 
to the time that the client acquires the lease (i.e. when it receives
the DHCPACK)?

In a perfect world, the former would make sense because the time to get
from DISCOVER to ACK should be just a couple of 
seconds at most. 

In a not so perfect world, the latter would make sense. For example, if
the network or DHCP server is not performing very well, it may take many
seconds and several retries to actually get from DISCOVER to ACK. If
this happens and the DISCOVER time 
is the reference, then there could be a considerable discrepency 
between the client's and server's notion of when the lease 
should expire.

Am I correct, or did I miss another section of the document that
clarifies this?

--kan--
--
Kevin A. Noll, KD4WOZ
CCIE 10948, CCDP
Perfect Order, Inc.		
Kevin.Noll@perfectorder.com
717-796-1936

_______________________________________________
dhcwg mailing list
dhcwg@ietf.org
https://www1.ietf.org/mailman/listinfo/dhcwg

_______________________________________________
dhcwg mailing list
dhcwg@ietf.org
https://www1.ietf.org/mailman/listinfo/dhcwg