Ping check and timeout

Thomas Marteau isc at marteau.org
Fri Oct 30 11:27:24 UTC 2009


Hi David,

Thank you for the reply. Why CLTT is sometimes taken in account and
sometimes not?
To be clear, I need to put a 60 second sleep between the release and
the renew to have the wanted bahevior?

--
Thanks, Thomas.



On Wed, Oct 28, 2009 at 5:58 PM, David W. Hankins <dhankins at isc.org> wrote:
> 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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