Dual Port Ethernet Problem

[Frank4d]

I have several computers at work with Intel 82546EB dual port ethernet controllers. Computers are running XP Pro SP1a with latest updates. Network adapter #1 is plugged into the corporate LAN, and network adapter #2 is not connected to the network at all.

If I setup network adapter #1 with a static IP and disable network adapter #2, I can access other computers on the network, and can ping other computers by name or IP. And other computers san see me.

But if I enable network adapter #2 (not connected to the network... just enabled) and also give it a static IP, I can still can still see other computers on the network, and can ping other computers by name or IP. But other computers are no longer able to access me.

So why does simply enabling both controllers (even though only one is connected to a network) screw up the one connected to the network?

 

[Frank4d]

Addition to last post...

If I enable adapter #1 with a static IP and enable adapter #2 for DHCP... when I log on, adapter #2 fails to get an IP (because it isn't plugged into the network) and XP assigns it an ARP 169.254.X.X address... and I don't have this problem. It is only when both adapters have static addresses.

 

[linney]

Is it something like this you are seeing?

Windows XP Setup Creates a Network Bridge Between Two or More Network Devices

http://support.microsoft.com/default.aspx?scid=kb;en-us;816486&FR=1&PA=1&SD=HSCH

How to prevent the Network Setup Wizard from creating a bridge in Windows XP

http://support.microsoft.com/default.aspx?scid=kb;en-us;283429&FR=1&PA=1&SD=HSCH

How to troubleshoot network connectivity problems

http://support.microsoft.com/default.aspx?scid=kb;en-us;325487&FR=1&PA=1&SD=HSCH

What is the Event Viewer telling you, if anything?

 

[Frank4d]

The behavior is very similar to having a network bridge between the adapters but there is no visible indication they are bridged.

I'll take a look at Event Viewer when I get to work.

 

[Frank4d]

I did not see anything in Event Viewer other than informational messages that the LAN adapters are enabled or disabled.

I spent a couple of hours this morning enabling and disabling, and plugging and unplugging cables. If both adapters are enabled, a cable must be plugged into adapter #2 to access any other computers, or for another computer to access adapter #2's IP. And a cable must be plugged into adapter #1 for other computers to access adapter #1's IP.

I'm not sure yet whether it's an Intel driver or XP thing, but I can live with it 'as-is' now that I understand the rules.