How to bridge two Lan Cards in Win2k

Posted on 2005-04-25
Last Modified: 2008-01-09
Hello experts!

All 5 PCs have Win 2k PRO installed. I also have the Win 2k Server but no time to mess with it at this point.
There are two DSL modems (2WIRE 1800), and each has a very small LAN connected. Each modem also works as a four port hub.
The first LAN, runs with a "" internal IP and a subnet called "HOMEX"
The second LAN, runs with the  "" internal IP, in a subnet called "HOME"
Both DSL Modems are configurable gateways that can use either IP: "" or "".

Pc1-- connects to --- Modem1 (has 2 LAN cards)
Pc2-- connects to --- Modem1
Modem1 connects as gateway to my ISP

Pc3-- connects to --- Modem2 (has 2 LAN cards)
Pc4-- connects to --- Modem2
Pc5-- connects to --- Modem2 ----- Modem2
Modem2 connects as gateway to my ISP

Pc3 and Pc1 each has two network cards (disabled for now).
I have been trying to connect both networks so I can access files in Pc3 from Pc1. I think this is called "bridging" both Pc3 NICS.
But I cannot figure out how. I know I can do it with WIN XP. Is this possible in Win2k? Any ideas?

Please be as specific as you can with the instructions to do this. Also, I don't understand drawings too much.
Thanks in advance.

Question by:jaimexctsg
    LVL 21

    Assisted Solution

    To have all PC's communicate they would have to be on the same subnet currently they are on different networks. When you have two different networks the only way to get them to communicate is to have a physical router or setup your Windows 2000 server as a software router....

    A better way would be to change your IP Addresses "" & "".

    to match in other words set up your IP addressing scheme so it goes, etc...

    being that you have two different IP addresses unless you have a router one will not talk to the other because they are regarded as seperate networks.
    LVL 27

    Assisted Solution

    I agree with Brian.

    I would add a couple of things.

    You have to make sure your modems don't both want to be .1 in the network - this is usually the case with Small Offic/Home Office (SOHO) gear.  So, make sure you can change one modem to be .2 or .5 or whatever.  

    After changing one of the modems internal IP, and the network to match each other, you'll need to connect the two modems with a crossover cable.  THAT will create the bridge - the two modems will be briding to different Ethernet segments.

    So, communication from PC3 to PC1 will work like this:

    PC3 will ARP (get the MAC address) of PC1 by broadcasting an ARP request and PC1 will respond.
    PC3 will put PC1 in its destination address and put it on the wire.
    Modem2 (switch2) will get the frame and examine the source and destination and consult a table of ports and decide that PC1 lives on the port going to Modem1 (assuming it already knew this).
    Modem1 (switch1) will get the frame and examine the source and destination and consult a table of ports and decide that PC1 lives on the port going to PC1 and switch it over to the port.
    PC1 will get the frame and examine the destination address and decide that it is the intended recipient of the frame and will send it up the stack for processing.

    Now, PC's on modem2 can have the IP for modem2 as their default gateway, and have the modem1 as the backup default gateway, if this setting exists in their TCP/IP stack.  Vice versa for PC's on modem1.

    OR you may want to look into picking up a load balancing gateway router like this one: and then all your PC's could use the same settings for default gateway.

    Author Comment

    Thanks for your feedback.
    It will take me some time to try all this out but I'll keep you posted.

    Author Comment

    Forgot to tell you, I was giving the wrong IP for the modems, both modems will allow me to set their Ip Address to either or but I cannot assign them or
    LVL 27

    Expert Comment

    You can't change them from anything besides .1?

    Author Comment


    Author Comment

    In trying to explain what  made it work I just realized that if I had to move my PCs, I wouldn’t be able to reconnect them. In general workgroup HOME contains all the five PCs. All of them run in the subnet and connect through a hub switch to the ADSL Modem. For this they each use one of the two lan cards (Nics) installed, and hub switches to connect them. At the same time, there are two PCs that use another hub switch that connects them to the subnet. This one connects them to the other modem.
    My question now is: Can the same switch be used to provide the connections for both LANs at the same time? This would conclude my networking nightmare.
    LVL 2

    Accepted Solution

    Let me make sure I understand:

    Switch1 is connected to modem1 ( as well as PC1, PC2, PC3, PC4 and PC5.  This comprises the  network.

    Switch 2 is connected to modem2 ( as well as PC1 and PC3.  This comprises the network.

    PC1 and PC3 each have 2 network cards (are dual-homed) so each can use either network.

    If the above is correct, the short answer is yes, you can connect everything through a single switch.   Both modems and each PC would be plugged into the switch, plus PC1 and PC3's second network card would also be plugged into the switch.  Not elegant, but workable.

    Author Comment

    This question has the most difficult problem to solve! There has been one piece of information missing. Modem 1 is not connecting to anything. Thanks to everyone of you. I will split more points be3cause all your information was very helpful.
    Thanks again,

    Author Comment

    LarryHo, you explained it perfectly!

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