Two NICs - Use Different DHCP Server?




I have several test machines with 2 NICs installed. I usually use thes
test machines in a standalone test network (in the 192.168.0 subnet),
and I have my own DHCP server on the test network that is configured
with MAC reservations, i.e., so that it serves IP addresses to the test
machines based on their MAC addresses, and all these test machines are
configured to "Obtain IP address" (I need to do this, rather than using
fixed IP addresses, for some other reasons).

All of these test machines are wired into a switch that is basically
embedded in the rack they're all in.

Right now, if I want to get external Internet access from any of these
test machines, I am shutting down my test DHCP server (just to be safe),
running a cable from the rack-embedded switch to a jack in the wall, and
then doing an "ipconfig /renew" on a test machine, which then gets it's
IP address (in the 192.168.2 subnet) from the office's DHCP server.

Since I have two NICs on each of the test machines, I was wondering if
it would be possible to configure things so that I could leave my test
DHCP server running all the time, keep the cable to the office network
plugged in all the time, and have one of the NICs get its IP address
from the office DHCP server, and the other of the NICs get its IP
address from my test DHCP server?

I guess that ideally, I'd like to be able specify which DHCP server each
NIC should use, or something along those lines, but I haven't been able
to find any way to do this.

Does anyone know how I can configure something like this?




Doug Sherman [MVP]

Simplest way is to get a second switch. Since you only have 'several'
machines, this would not be expensive. Connect one NIC on each computer and
your DHCP server to the new switch and connect the other NIC in each
computer to the existing switch.

Doug Sherman



Sorry, but I probably wasn't clear about the hardware configuration.
All the "several" machines are in a single rack, and the NICs on the
individual machines are routed directly to an embedded GigE switch
that's part of the chassis. Then, there are several ports on this same
switch that you can connect to the external world.

In other words, all the GigE interfaces for all of the test machines are
homed on the embedded switch, and I don't have access to the individual
interfaces, so I can't connect the interfaces to an external switch.




Phillip Windell

Split the Switch into VLANs if it isn't already. A switch split into VLANs
behaves as two different switches. If you split a 24port switch into two
VLANs with 12 ports in each then you effectively have two 12port switches.
The two halves of the switch will not communicate with each other unless
there is a router setup to route between them.


Phillip Windell [MCP, MVP, CCNA]

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