Windows XP computer with two NICs

[mlc9]

I know something similar has been posted before, but mine is acting a little differently.

I have two NICs in one PC. One accesses our LAN & Internet, while the other connects via ethernet cable to modems, routers, etc in order to configure. So basically, that connection is just passing local 192.xx traffic back and forth between a connected device.

Regarding the interface that I only use to configure devices, I have set that TCP/IP metric to a higher number than that of my LAN connection. When I connect a device up to that secondary NIC, the LAN will stay up for a while< but then always go go down. Usually, it goes down after I have finished my configuring of device on the NIC and reboot it.

Any thoughts to keep get my LAN to stay up all the time?

 

[kwing112000]

Do you have a default gateway on both? usually for a second NIC like that you can leave the gateway blank and it may help.

Kevin Wing
ACSS Small and Medium Enterprise (SME) Communications
ACS- Implement IP Office
ACA- Implement IP Office
Carousel Industries

 

[mlc9]

Second NIC is set for DHCP.

 

[Noway2]

It seems like the two NIC configurations cause problems with regards to routing as it gets confused as to which way to route packets. You would think that the metric would sort this out, but I don't think it does, or at least that didn't work for me. The net result is that the machine goes non responsive and appears that the network is down. What happens is that it receives the incoming data, but can't figure out how to get response packets back.

If your NIC is configured by DHCP chances are a gateway gets passed to it. If the primary NIC also has a gateway assigned then this can cause the conflict.

By adding the second NIC and simply assigning it a network and mask, it should automatically route to the local LAN without requiring a gateway.

 

[mlc9]

By local LAN, I assume you mean the routing only between the PC and the device it is plugged into to? I do not want the second NIC on the LAN / internet at all. It is only used to configure devices via ethernet cable (routers, modems, etc).

 

[Noway2]

By local LAN I mean one that is only assigned a private LAN IP (e.g. 192.168.0.0/24) with no gateway. I think this is what you intend for one of your NICs. For connecting a device and a PC via network cable, I would either use a cross-over-cable or plug them both into a router.

The thing to watch out for is that there is only one gateway assigned to the machine in total, not one for each LAN or ethernet device.

 

[DIACon]

As others mentioned, not adding a gateway to the NIC used for configuring devices should resolve the issue.

Alternatively, adding a custom route may solve your issue with the "route" command.

ROUTE ADD 0.0.0.0 MASK 0.0.0.0 X.X.X.X METRIC Y IF Z
^Gateway
By specifying the IF (interface), you may avoid these issues.

Of course X, Y, and Z are variables which will depend on your network configuration.

When your network connection fails, try going to the command line and typing "route print", is your internet traffic being routed over the wrong interface?

Chris Cantwell

http://www.DoItAllConsulting.com

http://www.DataPathinc.com

http://www.VoteForCantwell.com

 

[csamd]

Had same issue. My son at a university runs all of his stuff on his own network but is not allowed to connect a router to university network. We installed a second network adapter.

When you say that second NIC is set for DHCP, I assume that it is automatically obtaining an address. That's fine, but you're making the NIC LOOK for a gateway to nowhere.

Windows only allows one Gateway. Go to the properties page of network connections then to the property page of the lan connection that is not connected to the internet. Under Internet Protocol (TCP/IP), specify a static IP address and subnet mask (get the info from command prompt ipconfig.exe, use the one that your were already assigned) under "Use the following IP address". Leave Default gateway blank. Save it and you're done.

(Now if you really want to be cute, bridge the connections. Just kidding.)