Windows 7 / Networking

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Route

All IP-based networked devices, including computers, have routing tables. Routing tables describe the local network, remote networks, and gateways that you can use to forward traffic between networks. In networks with a single gateway, the routing table is very simple and indicates that local traffic should be sent directly to the local network, whereas traffic for any network other than the LAN should be sent through the gateway.

However, some networks have multiple gateways. For example, you might have two gateways on a LAN: one that leads to the Internet and another that leads to a private network. In that case, the local computer's routing table must describe that specific networks are available through the internal gateway and all other networks are available through the Internet gateway.

Note A client computer is most often configured with multiple routes in remote access scenarios. Specifically, if a client is using a virtual private network (VPN) connection, there might be separate routes for the networks accessible through the VPN connection, and all other traffic will be sent directly to the Internet.

Typically, computers running Windows will be automatically configured with the correct routing table. For example, network administrators will configure the DHCP server to assign a default gateway. When making a VPN connection, the VPN server will provide routing information that Windows will use to update the routing tables. Therefore, you rarely need to use the Route command to view or update the routing table.

However, if you are having connectivity problems and you are connected to a remote network or if your local network has multiple gateways, you can use Route to diagnose routing problems and even test different routing configurations. To view the local computer's IPv4 and IPv6 routing tables, open a command prompt and run the following command.

C:\>route print

Fully interpreting the routing configuration requires a detailed understanding of IP networking; however, you can quickly identify default routes for traffic being sent to your default gateway by locating the Active Route with a Network Destination and Network Mask of 0.0.0.0 for IPv4 routes and an Active Route with the prefix ::/0 for IPv6 routes. Other Active Routes with a Gateway assigned cause traffic for the specific Network Destination and Network Mask to be sent through that gateway, with a preference for the route with the lowest metric.

If you must manually update the IPv4 routing table (you should typically make changes to the network infrastructure that assigned the routes to the client), you can use the route add, route change, and route delete commands. For more information, type route -? at a command prompt.

To update the IPv6 routing table, you must use the netsh interface ipv6 add|set|delete route commands.