It's Official, I hate DHCP!

It's official, after days of trying to get DHCP to behave in a
"Textbook" manner I am unable to get it to do what I want.

I have a split DHCP scope which is spread across two DHCP servers.
Both servers know about the entire scope but server 1 has the first
half and server two the second. Both servers are told to exclude the
other server's half of the address range.

Does anybody know how i force a set of workstations to only use a
particular DHCP server? It has to be done in a way which will also
work with a network boot disk so i can use RIS to pull down images to
one half of this DHCP scope only.

Thanks for any help.

Go:Gul

<snip>

> Does anybody know how i force a set of workstations to only use a
> particular DHCP server? It has to be done in a way which will also
> work with a network boot disk so i can use RIS to pull down images to
> one half of this DHCP scope only.

Hi,

Workstation doesn't care what DHCP it uses. It will take first answer that
it receives from DHCP broadcast (DHCP discovery). There is no easy way to
prevent this since this is how DHCP was designed.

But what you can do is setup different scopes (on all available DHCP
servers). Now you can configure different clients to use different scopes
based on class ID.

Using option classes
http://www.microsoft.com/resources/d...ionClasses.asp

Mike

<snip>

<inline>

"Go:gul" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> It's official, after days of trying to get DHCP to behave in a
> "Textbook" manner I am unable to get it to do what I want.
>
> I have a split DHCP scope which is spread across two DHCP servers.
> Both servers know about the entire scope but server 1 has the first
> half and server two the second. Both servers are told to exclude the
> other server's half of the address range.

This is a very bad idea. Rather, you should set scopes on each server that
are differnet and do *not* overlap. Here's why:
If one of the servers actually does fail and you decide (for some crazy
reason) to enable the entire scope on the remaining server by removing the
exclusion, everythign will work as advertised - until the other server comes
back ... wherupon it will begin leasing addresses within the now valid
address range of the other server. What then?

Address pools should NEVER overlap.


> Does anybody know how i force a set of workstations to only use a
> particular DHCP server? It has to be done in a way which will also
> work with a network boot disk so i can use RIS to pull down images to
> one half of this DHCP scope only.

Only with reservations

There shouldn't be a problem with this as you only need to know the MAC
address of the card in the workstation and add it to the reservation on the
DHCP server you prefer.

-ds

Why are you setting this up this way? Redundancy? DHCP requests are done
via broadcast, whoever responds quickest will service the request. The only
way to separate clients and their respective DHCP servers are by physical
separation of subnets, or VLAN separation, both of which require routers to
route between subnets.

"Go:gul" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> It's official, after days of trying to get DHCP to behave in a
> "Textbook" manner I am unable to get it to do what I want.
>
> I have a split DHCP scope which is spread across two DHCP servers.
> Both servers know about the entire scope but server 1 has the first
> half and server two the second. Both servers are told to exclude the
> other server's half of the address range.
>
> Does anybody know how i force a set of workstations to only use a
> particular DHCP server? It has to be done in a way which will also
> work with a network boot disk so i can use RIS to pull down images to
> one half of this DHCP scope only.
>
> Thanks for any help.
>
> Go:Gul
>
>

"Dave Shaw [MVP]" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> If one of the servers actually does fail and you decide (for some
crazy
> reason) to enable the entire scope on the remaining server by removing the
> exclusion, everythign will work as advertised - until the other server
comes
> back ... wherupon it will begin leasing addresses within the now valid
> address range of the other server. What then?

Never had that problem and have run ours that way for a long time.

--

Phillip Windell [MCP, MVP, CCNA]
www.wandtv.com

Actually, this will not result in clients using different scopes. Option
classes will only result in clients getting different sets of options from
within the same scope.
A client is assigned its IP based on which subnet it is connected to, not
which class ID it provides.

-Chris
--
==============================
Chris Edson
(E-Mail Removed)

This posting is provided "AS IS" with
no warranties, and confers no rights.
===============================

"Miha Pihler" <mihap-(E-Mail Removed)> wrote in message
news:%23i%(E-Mail Removed)...
> <snip>
>
>> Does anybody know how i force a set of workstations to only use a
>> particular DHCP server? It has to be done in a way which will also
>> work with a network boot disk so i can use RIS to pull down images to
>> one half of this DHCP scope only.
>
> Hi,
>
> Workstation doesn't care what DHCP it uses. It will take first answer that
> it receives from DHCP broadcast (DHCP discovery). There is no easy way to
> prevent this since this is how DHCP was designed.
>
> But what you can do is setup different scopes (on all available DHCP
> servers). Now you can configure different clients to use different scopes
> based on class ID.
>
> Using option classes
> http://www.microsoft.com/resources/d...ionClasses.asp
>
> Mike
>
> <snip>
>
>