Subject: RE: Load (re)balancing for renewals.

From: Kim Kinnear <[email-masked]>
Date: Fri, 11 Feb 2000 15:48:42 -0500

I feel like this isn't a big deal, and what experience
we have in practice seems to bear that out.

Though using the server-identifier to "change" the DHCP server is
a neat trick if you know the other one is up.  I believe that is
what Ted was suggesting.  (Though not, I think, what Steve
thought Ted was suggesting.  There is no NAKing involved in this
approach.)

If we want to solve this "problem", that is the solution that I
think we should use.

I don't think shortening the renewal interval is necessary or
useful in this case partly, I suppose, since I don't think having
the secondary renew leases is in general a big problem.

I'm thinking too that increasing the load on the secondary
(sooner than necessary) is not a good idea.  Remember that over
time, the renewal times will get shorter and shorter until they
equal the MCLT, and then they will be the MCLT until the primary
comes up or someone tells the secondary that the primary is down.

Cheers -- Kim

At 02:39 PM 2/11/00 -0500, Steve Gonczi wrote:
>Yes, I like Ted's suggestion too. I was primarily concerned with 
>pointing out the issue, and my solution was to some degree, improvised.
>
>I believe this issue is worth solving. It is clearly possible that clients
>get spontaneously redistributed but (IMHO) it is not probable.
>
> >Yes, I like that far better than Steve's suggestion of waiting until
> >T2's broadcast.
> >
> >Also, doing nothing likely isn't that big a deal. Eventually the
> >clients will get redistributed (of course the secondary server
> >will need to be down at a renewal or the client will have to have
> >the lease expire - such as if it is removed from the network).
> >
> >- Bernie
>

---

From: Ted Lemon <[email-masked]>
Date: Fri, 11 Feb 2000 13:43:37 -0800

> the secondary renew leases is in general a big problem.

What I suggested was not to shorten the renewal time, but to make the
renewal and rebind time the same - that is, if DHCP server B thinks a
client belongs to DHCP server A, but is assigning the client an
address because it knows DHCP server A is down, then it sends lease T1
and T2 times that are identical, or just sends a T2 time that's half
the lease duration.   This will cause the client to broadcast its
first renew, which will then be picked up by server A if it's back up
by then.

			       _MelloN_