We help IT Professionals succeed at work.

Need 2 networks with 1 DHCP server

I need to set up 2 seperate networks at a single location. I would like to set one up as a 192.168.0.0 and the other as a 10.0.58.0 network. I have 1 DHCP server on Windows 2003 Standard Edition. I do have 2 nic cards in the server. Could I have 2 networks set up in the DHCP server each associated with one of the nic cards, then go to a Layer 3 switch with 2 VLANS and route bewteen the 2 VLANS at the switch? If this is possible, how do I go about associating each network with the specific nic? Any help or ideas would be appreciated.

Barry
Comment
Watch Question

You only need to use your one NIC. On the L3 switch create your two vlans. Then on the vlan that's not on the same subnet as your DHCP server assign an IP helper like so:
config t
int vlan XXX
ip address 10.0.58.1 255.255.255.0
ip helper-address [ip of DHCP server]
This will forward your second vlans DHCP broadcasts to the DHCP server. You'll need to create another DHCP scope for this new subnet. Then when the DHCP broadcasts come in from the new subnet they're seen as coming from the L3 switches vlan interface [10.0.58.1] of the new vlan and will be assigned an address out of the new DHCP Pool.

Author

Commented:
So are you saying that the switch will aid in the computers picking up their ip from the DHCP server based on its configuration?
Yes, that's corrent. If you create the second VLAN and put in the settings from my first post it will send your new VLAN's DHCP requests to the DHCP server. I do it all the time.

Author

Commented:
Now without the Layer 3 switch and the VLAN, I will end up with 2 DHCP networks and computers could randomly get either network ip address, correct? Also, in order for this to work I definitely need a Layer 3 switch, correct? Would a Layer 2 that supports VLANS work? I was under the impression that for one network to route to the other and pass data a Layer 3 switch was needed to route the data?

Ahmed Abdel SalamPh.D. Candidate

Commented:
you can use in layer two switch as well, just create two vlans then configure your DHCP relay.
which switch do you have ??

Author

Commented:
We are looking at a Netgear Switch FSM726 We have not set this up yet.

Author

Commented:
The other one we are looking at is the FS750T2 by Netgear. I think with this one we may need a router.
Ahmed Abdel SalamPh.D. Candidate

Commented:
this one has Vlan options so I think it should support DHCP relaying..
The DHCP relay takes place at layer 3. A layer 2 switch wont do this. If you use a layer two switch, you'll need a router that will accept VLAN traffic (802.1q trunking/VLAN tagging), and on this router you will configure the DHCP relay.
There are two ways to do this.
A. VLAN a L2 switch and use one port from each vlan to connect to a router interface (an actual configurable ethernet interface, not a switch built into the router). Then you could config the DHCP relay in the vlan config on the routre.
B. Config 2 vlans on the L2 switch, then configure one of the switchports as a TRUNK port which passes both vlan's information (via VLAN tagging). Then that trunked switchport plugs into a router interface configured with trunking. You'll most likely be using 802.1q trunking protocol. Then config the DHCP relay on the router.
Ahmed Abdel SalamPh.D. Candidate

Commented:
soo sorry... I answered it by mistake:( stuknhawaii, you are correct.
applogise for misunderstanding ..  

Author

Commented:
Thanks for the info. I see what we need to do now.

Explore More ContentExplore courses, solutions, and other research materials related to this topic.