Correct Failover / DHCPOFFER functionality

David W. Hankins dhankins at isc.org
Mon Jul 6 17:24:42 UTC 2009


On Fri, Jul 03, 2009 at 01:49:34PM +0530, pat wrote:
> I guess you are mentioning the field seconds elapsed in DISCOVER message ?,

Yes, I presume that's what your capture software is naming it.  In the
RFC's, the field is labeled 'secs'.

> My load-balance-max-secs is 3  and the SPLIT is 128 from dhcpd.conf file,
> can you tell me what happens for the client with seconds elapsed is 18 and
> for the client with field same field set as 0.

Any client presenting a 'secs' value larger than 3 will not be load
balanced (so, less than or equal to 3 will be load balanced).

A value of 3 is often selected as this is seein on either the first or
second retransmission, depending on client state, and the next
retransmission probably wouldn't be until 6 or 8 seconds again (so
secs would be ~18 by then, which is a rather long time to wait for a
lease).

> what does this Sec field mention, is it configurable from client or server
> side to go through hashing always?

The 'secs' field is supplied by the client, and describes how many
seconds the client has been trying to get a configuration without
success ('secs' 0 is the first packet, from there on it roughly
describes how many seconds the client has been retransmitting).

-- 
David W. Hankins	"If you don't do it right the first time,
Software Engineer		     you'll just have to do it again."
Internet Systems Consortium, Inc.		-- Jack T. Hankins
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