

NT server config with IP forwarding, dial-up, routing and RAS won't work under Win2k

I have a configuration that was working fine under Windows NT, but I cannot make it work under Windows 2000. There is a local network, with one PC under Windows 2000 server (PC1), and other PCs under WinNT (net1), all of them on the same network. There is another two PC network with a PC under Windows 2000 professional (PC2), and a PC under Windows 95 (PC3). PC2 is configured to enable IP forwarding, and have a modem to call PC1. PC1 has a modem to receive the communication, and has Routing and Remote Access Service installed on it. I would like the computers of net1 to be able to ping PC3. When PC1 is configured to accept incoming connections, it is not possible to add static routes on it in order to ping PC3. How should I configure Windows 2000 Server?

So, you have two networks separated by a dial-up connection. PC1 is in NET1. PC2 and PC3 are in NET2. PC1 and PC2 are your dial-up machines.

The key to troubleshooting this problem is to know the IP addresses on each interface. You can only route if you have different networks on each side of the machines that are acting as routers. How have you configured RRAS on PC1 to distribute IP addresses? Are you using DHCP or have you assigned a set of static addresses?

On each machine, open a command session and run IPCONFIG. Write down the IP address assigned to each interface. Ensure that each interface is in its own network. Pay particular attention to the subnet masks. I?m inclined to think that NET1 and NET2 are running the same network ID.

When you make a dial-up connection from PC2 to PC1, the system creates a virtual WAN interface on each machine. The WAN interfaces will have IP addresses that are masked, so they are in a different network by definition.

Run ROUTE PRINT at each machine and check for the default gateways (the interface address entries for the listings.) You might also have a problem with the gateway configuration. Each boundary server needs to point at the partner as a gateway. You should not need static routes on either of the machines if you only have two networks.

If you can?t get it to work, feel free to write back with a drawing of the networks and the IP addresses/masks.

This was last published in February 2001

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