Two factors converge to make this work.
1.) The IP Helper address
Converts the broadcast request to a unicast. The destination being
the helper address, and the source address being the Router interface
that received the request *Very Important*
2.) The NT server is configured with one interface/IP address. A scope
is created for the directly connected network, and a scope is created
for the network on the other side of the router. These two scopes are
bound together as one superscope. (see NT/DHCP docs for how, like all
things NT, it's just a few button-pushes).
It works in this way. The DHCP server will assign addresses from a
scope which corresponds to the directly connected network on which the
receiving interface sits. The superscope binds the secondary network's
scope to the directly connected networks scope, in effect, saying "it's
ok to assign addresses from this scope to requests on this other
directly connected network".
Now, to answer your question. The source address of the forwarded
request is on the other net (remember the changed source address
above?). In this way, the NT server knows that it should assign an
address from the other nets pool.
HTH
-S.
Larry Lamb wrote:
>
> You'll only want the 1 IP on the server if the local network has 1 IP range.
> If memory serves me right, you just add a 2nd scope and setup the ip
> helper-address to the server. It acts as the DHCP relay and the server will
> know the request came from the other network. Hopefully someone will add
> something additional if this isn't correct. It's been ages since I've dealt
> with this.
>
> "Hatim badr" <[EMAIL PROTECTED]> wrote in message
> [EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> > Thank you for your response
> >
> > I want tp put 2 scopes in that server, which means that I have 1 IP
> address or
> > evan two but how can I force a client to take from specific scope
> >
> > Thanks
> >
> >
> > "Larry Lamb" <[EMAIL PROTECTED]> wrote:
> > As long as you have a router to move the traffic between the two VLANs,
> you
> > can use the ip helper-address to forward the broadcast to a known unicast
> > address for the DHCP server.
> >
> > "Hatim badr" <[EMAIL PROTECTED]> wrote in message
> > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> > > Dear All,
> > >
> > > I'm using Windows NT DHCP server with 2 scopes in that server. I'm
> > creating 2
> > > VLANs. To be able to use the DHCP with this situation , I'm using 2 NIC
> > card ,
> > > one for each VLAN.
> > >
> > > I wonder if I can use only one NIC card and the IP HELPER ADDRESS with
> it!
> > > given that I want to use the same structure, I mean each VLAN has its
> own
> > > scope.
> > >
> > > Thanks
> > >
> > > Hatim
> > >
> > >
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