DHCP on specific interface

[disturbedone]

Is it possible to define which NIC DHCP responds to? Well there's a bit more to it than that....

The scenario: HP server with Broadcom NetXtreme Gigabit NIC that supports VLANs so have created 2 virtual interfaces, one for each VLAN (they appear in Network Connections as separate NICs). Cisco ESW-500 switch uses CDP with IP phones to automatically allocate the VLAN ID before it gets DHCP. Now I need SBS2K3 to allocate the correct scope.

I have it allocating addresses at the moment so at least I have some service. But I need to get it allocating correctly. One problem I have noticed is that although the phone gets a lease it doesn't appear in DHCP admin!

DNS admin allows me to specify which IP address (and therefore NIC) to listen on. Something along those lines for DHCP is what I'm after but there's more to it because it needs to specify which scope.

Any ideas?

 

[disturbedone]

UPDATE:

DHCP Admin, right-click server, Properties, Advanced tab, Bindings....this can disable the server from responding to DHCP requests on a specific NIC but....doesn't resolve the issue of allocating a specific scope to a specific NIC/VLAN.

However, with the following config I get some results...
* NIC1 192.168.1.1/24 on VLAN1 (via HP Network Config Utility)
* NIC2 192.168.100.1/24 on VLAN100
* DHCP scope 192.168.1.11-254/24
* DHCP scope 192.168.100.11-254/24
* Phone is allocated VLAN100 via Cisco ESW-500 switch using CDP
* Phone obtains 192.168.100.x address
* When CDP is disabled phone is put in default VLAN1 and obtains 192.168.1.x address
* The problem is that no lease shows in W2K3SBS DHCP admin. Frequently the 'Address Leases' in DHCP Admin (for both scopes) gets a red cross against it, refreshing clears this but still no leases show........

UPDATE: what do you know? It now shows up the leases!! The only thing I did between it not showing and showing was disabling/enabling CDP on the switch to test it getting a different scope lease.

I guess when the request comes in to the physical NIC it looks at the HP Network Config to see which virtual NIC is associated to VLAN100. It finds that 192.168.100.1 is the address on the NIC for VLAN100 and then passes it to DHCP to look for an address in the 192.168.100.x scope. And vice versa for VLAN1.

 

[Bas1234]

Why use two nics?

Add a new scope on the first NIC, make sure you have a Core switch or a Layer 3 switch that has VLAN routeing enabled.
Make use the switch has an inteface address in the VLAN100

Then you need to do a route add on the DHCP server.

Open CMD;

route add 192.168.100.0 mask 255.255.255.0 192.168.1.x -p

-p is to make it permanent, .x is the routing swtich.

On the routing switch you need to add an ip helper address to find it's way to the dhcp server, and the route add is for the dhcp server to find the VLAN100.

Now when a phone tries to get DHCP in VLAN100 it should get
192.168.100.x/255.255.255.0/192.168.100.x (.x is the interface address of the routing switch on the VLAN100)

By sending a vendor class option in the 192.168.1.0/24 network you should be able to the any extension that they a need to go to VLAN100.

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It works! Now if only I could remember what I did...

Dain Bramaged
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