Ping check and timeout

[David W. Hankins]

On Wed, Oct 28, 2009 at 10:41:30AM +0100, Thomas Marteau wrote:
> The first one is OK and you can see the 14 second offset between the
> DISCOVER and the OFFER and the second is the problem.
> 
> Oct 28 10:09:30 instlinuxdsy dhcpd: DHCPDISCOVER from
> Oct 28 10:09:44 instlinuxdsy dhcpd: DHCPOFFER on 10.244.143.251 to
> 
> Oct 28 10:07:49 instlinuxdsy dhcpd: DHCPDISCOVER from
> Oct 28 10:07:49 instlinuxdsy dhcpd: DHCPOFFER on 10.244.142.124 to
> 
> Any idea where to start digging? Clients are identical in this example
> Windows XP 32 bits.

If the lease is static, or if the lease's CLTT is less than or equal
to 60 seconds ago, the server doesn't perform a ping check.

There's no config knob to adjust this behaviour, if it's not doing
what you want you'd have to look in server/dhcp.c and search for
"SV_PING_CHECKS".

I've always thought the CLTT check was pretty bogus but I wasn't
sure what I'd replace it with (current binding state != active?
this removes false positives but can have false negatives).

-- 
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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