Route Between Two Networks with a Server with Two Network Cards

networkingroutingwindows-server-2008

This is the first time I am faced with routing and it seems I have hit a dead end. I have the following scenario:

client1:

  • 192.168.1.10
  • 255.255.255.0
  • gateway: 192.168.1.100
  • DNS server: 192.168.1.100

client2:

  • 192.168.1.20
  • 255.255.255.0
  • gateway: 192.168.1.100
  • DNS server: 192.168.1.100

server (Windows Server 2008 R2 with enabled RAS & Routing Services)

network card 1 (connected to a switch along with the clients)

  • 192.168.1.100
  • 255.255.255.0
  • DNS server: 127.0.0.1

network card 2 (connected to the router)

  • 192.168.2.100
  • 255.255.255.0
  • gateway: 192.168.2.1
  • DNS server: 127.0.0.1
  • (DNS forwarding to 192.168.2.1)

ISP router (with connection to internet)

192.168.2.1

Now in this scenario I have tried to route traffic from the 192.168.1.0/24 network with the clients to the 192.168.2.0/24 network with the routers to connect them to the internet.
However, no matter what I do I get no positive ping to the router 192.168.2.1.

Test ping from 192.168.1.10

  • to 192.168.1.20: Success
  • to 192.168.1.100: Success
  • to 192.168.2.100: Success
  • to 192.168.2.1: not reachable

The routing table contains the 2 routes 192.168.1.0 and 192.168.2.0 as directly connected.

Does anyone know where the routing fails?

I have searched different forums but mostly found nothing relevant. One post however pointed out that in a similar situation the problem was that the router doesn't know the way back and the internet router would need a static route back to the first router.
If that really is the case, I take it there is no solution with my equipment, because the standart ISP router doesn't allow to set any static routes.

Best Answer

To summarize the comments -

Your clients on the 192.168.1.0/24 network are unable to reach the Internet or ISP router (192.168.2.1) because that router does not have an explicit route to the 192.168.1.0/24 network through the RRAS server (192.168.2.100).

Possible solutions:

  • Add a static route on the 192.168.2.1 router from the 192.168.1.0/24 network through a gateway of 192.168.2.100.
  • Combine the two separate subnets so they are on the 192.168.1.0/24 (or /23) network, which is local to that ISP router.
  • Have the RRAS server perform NAT on the connections so that the ISP router will see the connections as coming from 192.168.2.100 instead of the actual source.
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