How to Route Different Traffic Through Different Network Interfaces in Windows

iplocal-area-networknetworkingroutingwindows

I've searched for details on how to do this but I've been unsuccessful – I wondered if someone could offer up some advice.

So, let's say I have 2 network cards (LAN and 3G in my instance), both assigned dynamic IP addresses. The LAN interface is my corporate LAN, and I'd like to use the 3G interface for all other access (ie, t'internet!).

I have little networking experience, but my feeling is that I should be able to make the 3G card the default gateway, and then force all traffic for a set of known subnets through the LAN interface.

Here's a route print

===========================================================================
Interface List

 40...........................Vodafone Mobile Connect
 12...00 16 cf 87 71 22 ......Dell Wireless 1500 Draft 802.11n WLAN Mini-Card
 11...00 15 c5 58 47 24 ......Broadcom NetXtreme 57xx Gigabit Controller
 24...00 50 56 c0 00 01 ......VMware Virtual Ethernet Adapter for VMnet1
 25...00 50 56 c0 00 08 ......VMware Virtual Ethernet Adapter for VMnet8
  1...........................Software Loopback Interface 1
 26...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter
 13...00 00 00 00 00 00 00 e0 Teredo Tunneling Pseudo-Interface
 21...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #2
 23...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #4   
 28...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #6
===========================================================================

IPv4 Route Table
===========================================================================
Active Routes:
    Netork Destination        Netmask          Gateway       Interface  Metric
          0.0.0.0          0.0.0.0     10.183.148.5   10.183.148.157   4235
          0.0.0.0          0.0.0.0     10.183.148.6   10.183.148.157   4235
          0.0.0.0          0.0.0.0     10.183.148.7   10.183.148.157   4235
          0.0.0.0          0.0.0.0         On-link      10.57.175.79     31
     10.57.175.79  255.255.255.255         On-link      10.57.175.79    286
     10.183.148.0    255.255.255.0         On-link    10.183.148.157   4491
   10.183.148.157  255.255.255.255         On-link    10.183.148.157   4491
   10.183.148.255  255.255.255.255         On-link    10.183.148.157   4491
       127.0.0.0        255.0.0.0         On-link         127.0.0.1   4531
        127.0.0.1  255.255.255.255         On-link         127.0.0.1   4531
  127.255.255.255  255.255.255.255         On-link         127.0.0.1   4531
      169.254.0.0      255.255.0.0         On-link    10.183.148.157   4511
  169.254.255.255  255.255.255.255         On-link    10.183.148.157   4491    
      192.168.6.0    255.255.255.0         On-link       192.168.6.1   4501
      192.168.6.1  255.255.255.255         On-link       192.168.6.1   4501
    192.168.6.255  255.255.255.255         On-link       192.168.6.1   4501
     192.168.73.0    255.255.255.0         On-link      192.168.73.1   4501
     192.168.73.1  255.255.255.255         On-link      192.168.73.1   4501
   192.168.73.255  255.255.255.255         On-link      192.168.73.1   4501
        224.0.0.0        240.0.0.0         On-link         127.0.0.1   4531
        224.0.0.0        240.0.0.0         On-link    10.183.148.157   4492
        224.0.0.0        240.0.0.0         On-link       192.168.6.1   4502
        224.0.0.0        240.0.0.0         On-link      192.168.73.1   4502
        224.0.0.0        240.0.0.0         On-link      10.57.175.79     31
  255.255.255.255  255.255.255.255         On-link         127.0.0.1   4531
  255.255.255.255  255.255.255.255         On-link    10.183.148.157   4491
  255.255.255.255  255.255.255.255         On-link       192.168.6.1   4501
 255.255.255.255  255.255.255.255         On-link      192.168.73.1   4501
 255.255.255.255  255.255.255.255         On-link      10.57.175.79    286
===========================================================================
Persistent Routes:
  None

So, interface 40 is my 3G card, and interface 11 is my LAN card. You can see that (I think) I have two default routes currently but the 3G wins because of the lower metric? I need to force all 10.183.. traffic over LAN interface.

Best Answer

The command you're looking for is route add:

route | Microsoft Docs

For your setup, I think the syntax is:

route add 10.183.0.0 mask 255.255.0.0 10.183.148.5

This will send all the traffic for 10.183.x.x to the next hop address of 10.183.148.5 which your system already knows is off of your ethernet nic, and any traffic that doesn't match a route, will be grabbed by your default route and head through your 3g connection. It also looks like your network assigns multiple routers, so you might want to double it up and add the routes for 10.183.148.6 and .7 as well.

You might need to be careful if your network has stuff not in the 10.183 range, you may need to add more routes. You may also be able to get away with routing all of 10.0.0.0/8 to your corporate network, since windows will have a more specific route, but i'm not 100% sure on that since your 3g card is giving you an IP in the 10.x.x.x range.

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