Multiple leases

Eustace, Glen G.Eustace at
Thu Jun 8 23:00:56 UTC 2006

> It's less fuzzy.  It all starts with this:
> 	Seconds elapsed: 4
> That's set on both DISCOVERs in both traces.
> I'm guessing you have load balance max secs set to less than this
> because both of your failover servers are answering.

It is set to 3, I pressume from your comment that I should probably set
it to something like 5 or more.  My goal is to always have the local
server's response accepted first and to only make an offer from the
secondary if the client tries again i.e. the primary didn't respond.
> If the lease is ACTIVE (which it should be the second time because
> there's only 9 minutes inbetween these two and you gave it a 1-hour
> lease) both servers should choose that lease to offer.

This is a bit of a mystery, I have explicitly set the default-lease-time
to 86400, I can not see where the 1 hour is coming from.

> If the lease is FREE or BACKUP (does the client release its lease?),
> then the behaviour is more reasonable - both servers must answer, and
> they can only offer leases in one of those two states.

I would guess that they don't as there a very few RELEASE messages in
the logs, it would appear that MacOS X doesn't do a release when a NIC
is shutdown. 

> Best place to look now would be at your failover relationship...if
> the lease went active on one server, and that didn't propogate to
> the other server, I think it would result in this.
> Certainly in 9 minutes the servers should have been able to process
> that binding update.

I am not sure that I agree.  The client only seems to end up with a
different IP (lease) when the Xserve is involved in the conversation. In
both traces, the local server x.x.192.34 responds with an OFFER but with
two different IP No.s The secondary DHCP server's OFFER is after the
clients REQUEST in both cases and is for the same lease, which has a
different IP x.x.217.87 as it is from the secondaries pool. The IP
OFFER'ed by the secondary is not accepted by the client as it receives
an ACK from the primary to its REQUEST.

 .*.  | Glen Eustace, Infrastructure Development Engineer
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