[K12OSN] LTSP Setup question.

Jim Christiansen christiansen_j at hotmail.com
Sat Oct 16 17:22:40 UTC 2004

Hello Samps,

Oh man - this is a gem for me, although I'm now asking for some 
clarification.  I'm the teacher who is running one mixed network of K12LTSP 
(80 boxes) with an NT domain and now a 2k or 2003 server for administrators 
all on a new fibre backboned network - suggested last spring, by many on 
this list (to overcome all of the 600 volt power issues in the ceilings of 
  My technicians are way to busy to experiment on a working system and come 
to me for "the plan".  I'm a KISS (keep-it-simple-stupid!) kind of person 
and have said that to avoid DHCP hang ups, I wanted only one dhcp server on 
my network and it would be the k12 server.  This way my thin client will be 
the only boxes using dhcp, period - no problems.  All other boxes are static 
IP.  With a reference to one sheet of paper (my ip number list) I can ssh or 
vnc into any local linux or win box for maintenance - no "I wonder what the 
ip of that dhcp driven box is?"

I'm not too sure what the overall benefit would be to running dhcp for the 
administrator-vp-secretary-councelling win boxes is.  My school won't have 
more than 254 boxes total in it for some time (years).  I guess that what we 
would gain though is better access for notebooks (gota keep the travelling 
big-wigs happy)  or maybe a dhcp wireless access.

Come to think about it, this would be great...  When my kids come in for a 
week-end lan party, they wouldn't have to reset their networks either.

OK, so if my current set up is a 192.168.1.x system, and I wanted to move 
all of the win boxes to dhcp, what would I need to do using the map that 
Samps has given below?

All I would need is for a 192.168.1.x/21 network
one win dhcp server         -
one k12 dhcp server        
one wireless router gateway - (for notebook 

I know that I've set up my current dhcp server at

The /21 is what is different.

How will the three systems acces my one IPCop gateway/firewall out of the 

I'm excited to give this a go!

Thanks for any advice,  Jim

Terrell Prudé, Jr. wrote:

>You're very lucky indeed, unless you're running your K12LTSP servers in the 
>"standard" 2-NIC architecture.  Having eight DHCP servers serving the same 
>broadcast domain can be very, very dangerous.  Yes, I know some



When running the domain in a private IP block (10.255 and 192.168) you
can run as many DHCP servers as you can make subnets.

an example:

A network,, has 2046 usable addresses, from to (255 is broadcast and can't be allocated for
other use.

Each of four DHCP servers are set up to use as RANGE and
DHCP server 1 is using a SCOPE of to
DHCP server 2 is using a SCOPE of to
DHCP server 3 is using a SCOPE of to
DHCP server 4 is using a SCOPE of to

No overlaps in the scopes ensures that there won't be address-clashes on
the network.

If you subnet using a further 1 bit, then you can have twice as many
DHCP servers, each serving half as many clients.



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