We're considering two NBN fibre connections to the Internet (NBN is a fibre connection for those of you not living in Australia), with each connection having it's own subnet.

The first connection's subnet is and the second's is Half of the office will be on one the first subnet using one connection, and the other half will be on the second subnet using the other connection.

I want to ensure that the two subnets are able to talk to one another. For example, John's computer is and he needs to access resources on the server Altitude on, while Alan's computer is and he needs to access resources on the server Jelly on

Can this be done by connecting the two separate routers together, or does there need to be a "bridging" router, with the LAN and WAN addresses having a 192.168.0.x and 10.0.x.x addresses and static routing rules configured?

Phyiscal Network Layout


No, you do not need a bridging device. A bridging device is something that makes two physical networks appear as one logical network, and since you are running a separate subnet on each network you don't need to bridge them. A bridging device is what you would use if you wanted to use the same subnet at both sites.

You just need a means of connecting the two routers. In your diagram you have a line connecting the two routers, and if this can be a direct network connection of whatever type (Fibre, Ethernet, etc.) then the routers can be configured so that traffic to the other subnet goes to the interface that connects that subnet, and all other non-local traffic will go to the default route, which goes out to the Internet.

If the two routers cannot be directly connected, then the diagram needs to be altered to indicate that they are not directly connected.

  • Do direct connections between the two networks depend on the router's capabilities? Router A has two IP address (LAN and WAN and Router B has two IP addresses (LAN and WAN I would assume that a direct connection between the two would require a third IP address on one of the routers, e.g., Router A having a LAN2 address of or Router B having a LAN2 address of – magnus May 14 '15 at 1:06
  • Yes, you would have a third subnet, such as, on the network that connects the routers. They should be able to do it unless they are SOHO routers--update the question with the router make and model so you can get some input on that. – Tony Hinkle May 14 '15 at 1:10

Assuming each router is the default GW for the local computers, yo can connect the two networks simply by having proper routes on the routers so that they can access the other side.


  • On Router A:

    • => Directly connected
    • => Router B
    • default ( => Internet GW
  • On Router B:

    • => Directly connected
    • => Router A
    • default ( => Internet GW

From your diagram it seems it's also possible Router A takes care of all routing, in which case Router B default GW itself could be Router A.

Also note that things relying on broadcast such as workgroups, mdns, etc. will not cross the network boundary. This mean people may actually notice the disconnect between the two sides.

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