[K12OSN] DHCP and PXE with two different Class of IP address

David Whitmer thewhitmers at gmail.com
Thu Dec 7 17:45:27 UTC 2006

On 12/6/06, Bert Rolston <bert.rolston at clear.net.nz> wrote:
> Hey folks,
> I know this little chestnut has been chewed over many times on this
> list. I don't remember my situation coming up. So first I'll describe
> the environment.
> =======================
> The current environment
> =======================
> An MS Network with AD, terminal server and MS DHCP server with CLASS B
> IP address scheme.
> They want to revitalise their old Win 9x / NT machines and are
> investigating using K12LTSP or locally installed Linux. They have a lot
> of old classic to PII Pentiums which are gathering dust.
> One option is to boot the LTSP terminals in kiosk mode to access their
> Windows Terminal server using the RDP client included.
> The other option is to install a lightweight Linux distro (Puppy or DSL)
> on all the machines and use the RDP client that way.
> They don't want to change their existing infrastructure if at all
> possible. Even making changes to their DHCP server is considered risky
> by the network admin. ANY adverse impact on their existing system is
> unacceptable.
> The network admin uses Ubuntu at home, but has been unable to get any
> Linux computer to authenticate to the AD at work.
> For that reason he only sees limited potential for Linux / OSS in their
> current environment.
> Users will authenticate to their AD through Windows terminal sessions.
> Later on they may enable access to the Linux desktop and apps.
> =======================
> My Question
> =======================
> Given that the current DHCP server issues Class B addresses.
> Can the K12LTSP DHCP server, which issues Class C addresses
>        - co-exist on the same physical media
>        - handle PXE requests from the old hardware,
>        - and not interfere with their current setup?
> If so what changes (if any) need to be made
>        - on the MS DHCP server,
>        - their current setup
>        - the K12LTSP server
> Thanks,
> Bert


A standard K12LTSP server setup uses two NICs: one to connect to the
main network, and the other to run the thin client computers on their
own subnet.  In the default setup, the K12LTSP server will only run
DHCP on the NIC that serves the thin client subnet.  The thin client
computers will then only be served by the K12LTSP server's DHCP when
they boot up, and their DHCP requests will be isolated from the main

RDP should work fine from the thin clients.  I've used RDP to access a
Windows PC using TS Client (I think that's the name).  Others on this
list have edited the K12LTSP server's lts.conf file to have RDP be a
boot up option on the thin clients.  I have not yet tried that myself.

The main thing to avoid disruptions on your main network is to go with
the standard 2-NIC K12LTSP setup, and connect all your thin client
computers to just the subnet K12LTSP is running DHCP on.  Then you
shouldn't have to change anything on the MS DHCP server.

David Whitmer

Director of Media & Technology
Calvary Schools of Holland (Michigan)
web: www.calvaryschoolsholland.org
email: thewhitmers at gmail.com

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