Windows

What o/s are you using?
Can you set a router table on them?
Create a different segment for one of them.
That way they won't see each other to pull addresses from one another, yet with the routing tables the clients will see the others on the second lan of your wan thru the servers to share info.
What have you set up for the gateway?

Without some sort of router or intelligent switch to segment the network you can't specify which DHCP server to pull from. Is it possible for you to use only one DHCP server in you topology?

I don't understand why there would be problems in this topology, unless there some kind of security or logging policy required by management. If this is a routed line with each DHCP server providing a range that would need to be routed between the two schools then turn off BOOTP forwarding on your router. If it isn't, and each range is distinct but still within the given subnet (i.e. not routed) then put in a switch and disable BOOTP forwarding between the two collision domains.

Hope that helps -

Let me arrange the topology.

Two DHCP servers, each for different school and each has clients, but only one hub ?

The simplest way is to avoid problems, segment (divide) the network. Add one other hub and use it only for one school, while the old one could be used by the others.

Now, probably these two schools want to communicate one to each other. Allow the server to function as router, therefore adding two network cards, one for each server. Connect the two servers using direct cable(crossed).

The cost should be minimal: one hub, two network cards and one UTP 5 cable with two RJ-45 jacks on each end.

This is how I would set-up the network.

This question was closed by the author