DHCP on multihomed (two NICs) machine

[klausner]

I have a multihomed (two NICs) system WinNT4 SP6 that I am trying to configure with two different distinct simultaneous DSL lines and two routers. The first is a gigabit NIC that works just fine through DSL Router1 (not DHCP capable) on IP xxx.xxx.xxx.xxx to the first DSL connection. The second is a 100megabit NIC that I can not seem to configure to use the DHCP server in Router2 (DHCP enabled) on IP yyy.yyy.yyy.yyy. When I go into Control Panel / Network / TCPIP Propeties and choose the second NIC (100MB) it properly shows "Obtain IP address from a DHCP server". However, when I click on the Advanced button, and choose the second NIC, even though it shows "DHCP Enabled" for the IP address, the gateway shows xxx.xxx.xxx.xxx, which is the address of Router1! When I remove or change this address to yyy.yyy.yyy.yyy which is the IP address of Router2 configured as the DHCP server, WinNT changes it back automatically to xxx.xxx.xxx.xxx even after rebooting! How can I have two NICs each pointing to its own router? I appreciate any help you can give me. I do not have the option of disabling the gigabit NIC as we need it.

David

[HWMC]

NT can only have one gateway configured. I would allocate static IP addresses to both cards.

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Howard Marsh
HWM Consulting Pty Ltd
Harbour City Computers
Queensland, Australia
Get paid to read your e-mail! (http://www.MintMail.com/?m=4422)

[klausner]

The GB NIC has a fixed IP. It's fine. The 10MB NIC is the one that I am trying to get DHCP'ed. Should I remove the gateway entry from BOTH NICs?
David

[JackLothian]

What howard is saying is important. NT can only have one active Gateway. Yes, you can seem to create multiple gateways by adding one for each NIC but only one of these defined will be active. The highest priority gateway that is confirmed as active will always be the only gateway in existance. This is logical because each machine must have a clear-cut gateway no matter how many NIC it has. Think of the situtation from the dual-homed machine's perspective not the perspective of its clients on the 2 sub-nets. To have 2 gateways is a contradiction.

Dual static IP addresses might not be possible. The the dual-homed machine might connect to a service that requires it to operate as a DHCP client, additionally the DHCP server might be configured to give a gateway address at connection. If so you are stuck with the DHCP server's provided gateway addess. So a user defined gateway may be not possible & at least one of the NIC might have to be a DHCP client.

[This message has been edited by JackLothian (edited 10-24-2000).]