Date: Wed, 15 Aug 2007 08:07:50 -0500 From: "Lacayo, Luis F" <lflacayo@cps.k12.il.us> To: "Olivier Nicole" <on@cs.ait.ac.th> Cc: freebsd-questions@freebsd.org Subject: RE: Question about failover with ISC DHCP Message-ID: <DF9ADFA9776D044B9A948BF17340776B015C892E@CO-XCS11.admin.cps.k12.il.us> In-Reply-To: <200708150210.l7F2A9iU007894@banyan.cs.ait.ac.th> References: <DF9ADFA9776D044B9A948BF17340776B015C88C6@CO-XCS11.admin.cps.k12.il.us> <200708150210.l7F2A9iU007894@banyan.cs.ait.ac.th>
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Oliver,=20
Thank you very much for your prompt reply.=20
Each school is allocated 16 class C's, (hopeful thinking that one day
each student will have a computer) but they are not all configured. We
only configure them as they need them, the largest school has only 5
class C's configured for their subnet.=20
I will run as you suggest, and let you know.=20
Thanks again.
Luis
-----Original Message-----
From: Olivier Nicole [mailto:on@cs.ait.ac.th]=20
Sent: Tuesday, August 14, 2007 9:10 PM
To: Lacayo, Luis F
Cc: freebsd-questions@freebsd.org
Subject: Re: Question about failover with ISC DHCP
Hi Luis,
> I am looking to replace my current DHCP server with the ISC. Right
now
> I have to servers which are working with split scopes. Some of my
> schools need over 600 IP's, so I have the school with a 255.255.240.0
> which give them 16 Class C, network, so to avoid conflicts I assign
the
> 3 lower to one server and the 3 highest to the other.=3D20
This part is really not clear: you have 16 class C, and you assing 3
and 3? What about the 10 others?
> Now comes the question, in the following section there is a split of
> 128. If I give a range of 3 class C's do I set this value to 128 or
> (128*# Class C Networks)? =3D20
Fron man dhcpd.conf
The split statement
split index;
The split statement specifies the split between the primary
and sec-
ondary for the purposes of load balancing. Whenever a client
makes
a DHCP request, the DHCP server runs a hash on the client
identifica-
tion. If the hash comes out to less than the split value, the
pri-
mary answers. If it comes out to equal to or more than the
split,
the secondary answers. The only meaningful value is 128,
and can
only be configured on the primary.
This is certainly not giving much information, but they suggest you
use 128, so try with 128 first.
I'd suggest that you let the load balancing run for a while, then you
can see how many clients are served by each DHCP server and you may
try to fine adjust the split value.
I have been using fail-over while I was preparing a new DHCP server
recently (so the clients could start using the new server and the
leases were transfered from the old to the new machine) and it was
really seamless.
Best regards,
Olivier
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