route a port to a specific nic

Perhaps you could elaborate a bit?  If this is something you want to set from the switch side, perhaps it should be posted in the networking section...but I'm happy to help here.  So you want to set one port on a switch to only work with one NIC?  If that's the case, and the switch is configurable, you can set an ACL on that port to only allow the MAC of that one NIC to access it.  If you need help doing this let me know what type of switch you're using (Brand and model) and I'll get you the config.

what is the type of your router??

I am using a hotbrick 401vpn x2 router for the companies main router we have terminal services for employee remote access.  Also have an Exchange 2003 email server and the routing is handled by the same router.  We have a primary and backup domain controller.

We also have a second DSL internet connection with a static ip address and a second router of the same type.

On the DC there is a second NIC which I would like to connect to the second router which would be connected to the DSL modem.

The reason for donung this is because we do off site data backup over a FTP connection.  Over the weekend there is a huge amount of data sent out and when users login to terminal services response times are slow.

So if I could connect the second router and modem and route port 21 to say go this this specific NIC with bi-directional communications and still maintain a firewall with the router.  DHCp is hanled by the DC and DNS.  The software that does the ftp backup is on the DC.

I hope this helps.

You could add a static route to the server that sends all traffic destined for a particular IP address or subnet out of the second interface using the Route Add command.

For example, just say the second router IP is 10.10.10.20 and the IP address of the offsite backup is 100.100.100.1, you could use the following command.

route add -p 100.100.100.1 mask 255.255.255.255 10.10.10.20

This would send all traffic destined for 100.100.100.1 out through the second router.

Yes that is great but I do not want all trafic to go to the offsite backup server.  I only want dort 21 to go to the second NIC.  The backup software determines the offsie location for examle:ftp.servername.com

There for I need to tell the DC that only traffic on port 21 needs to go through the second NIC.

Thanks for your response.  Any other suggestions.

It wouldn't send ALL traffic to the offsite backup server.  It would only send traffic that you want to go to the offsite backup server out through the second NIC.

The problem with the route statement above is that it doesn't specify that only the second NIC should be used for that traffic.  If that route is valid from both NICs, then both will be used for sending the FTP traffic.

What you want to do is make sure both routers are on different networks, and there's not route between them.  Put one of your NICs on each of your networks so this way only ONE of your NICs will have a valid route to that backup DSL modem for your FTP traffic.  So for instance, if your main network router is on a 192.168.0.x /24 network, put the backup DSL router on a 192.168.1.x /24 network and you should be all set.