Configuring IP Routes

Topics on this page: When to Define IP Routes | Viewing the Routing Table | Adding IP Routes

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IP routes can be created on the ADSL/Ethernet router to specify where it should send data received on a particular interface. Routes specify the IP address of the next device interface or Internet destination to forward data to, given the ultimate destination of the data.

A common type of route is a default gateway, which defines the IP address where all data is forwarded unless an IP route has been defined for the particular destination in question. Each time data is passed towards its destination from one Internet address to another, it is said to complete one hop.

When to Define IP Routes

Most users do not need to define IP routes. On a typical small home or office LAN, the existing routes that set up the default gateways for your LAN computers and for the ADSL/Ethernet router provide the most appropriate path for all your Internet traffic.

  • On your LAN computers, a default gateway directs all Internet traffic to the LAN interface on your ADSL/Ethernet router (assuming the device is configured in Routing mode). Your LAN computers know their default Internet gateway either because you assigned it to them when you modified their TCP/IP properties, or because you configured them to receive the information dynamically from a server whenever they access the Internet.
  • On the ADSL/Ethernet router, a default gateway directs all outbound Internet traffic to a router at your ISP. This default gateway is assigned automatically by your ISP whenever the device negotiates an Internet connection. (The process for adding a default route is described in "Adding IP Routes.")

You may need to define routes if your home setup includes two or more networks or subnets, if you connect to two or more ISP services, or if you connect to a remote corporate LAN.

Viewing the IP Routing Table 

Each IP-enabled computer and router maintains a table of IP addresses that are commonly accessed by its users. For each of these destination IP addresses, the table lists the IP address of the first hop the data should take. This table is known as the device's routing table.

If the IP Address Table page is not currently displaying, click the Advanced Setup button. The IP Route page displays by default.

The IP Route Table displays a row for each existing route. These include routes that were predefined on the device, routes you may have added, and routes that the device has identified automatically through communication with your ISP's network.

The routing table may also reflect a default gateway, which directs outbound Internet traffic to your ISP. This default gateway is shown in the row containing destination address 0.0.0.0.

The following fields display in the routing table:

  • Destination: Specifies the IP address of the destination computer. The destination can specified as the IP address of a specific computer or an entire network. It can also be specified as all zeros to indicate that this route should be used for all destinations for which no other route is defined (this is the route that creates the default gateway).
  • Netmask: Indicates which parts of the destination address refer to the network and which parts refer to a computer on the network. The default gateway uses a netmask of 0.0.0.0.
  • NextHop: Specifies the next IP address to send data to when its final destination is that shown in the destination column.
  • IfName: Displays the name of the interface through which to data is forwarded to the specified next hop.
  • Route Type: Indicates whether the route is direct or indirect. In a direct route, the source and destination computers are on the same network, and the router attempts to directly deliver the data to the computer. In an indirect route, the source and destination computers are on different networks, and the router forwards data to a device on another network for further handling.
  • Route Origin: Displays how the route was defined. Dynamic indicates that the route was predefined on the system by your ISP or the manufacturer. Routes you create are labeled Local. Other routes may be created automatically (see Configuring RIP), or defined remotely through various network management protocols (LCL or ICMP).
  • Action: Displays an icon () you can click on to delete a route.

Adding IP Routes

Follow these instructions to add an IP route to the device's routing table.

  1. From the IP Route Table page, click Add to display the IP Route - Add page.
  2. Specify the destination, network mask, and gateway or next hop for this route (see the descriptions of these fields above). 
To create a route that defines the device's default gateway, enter 0.0.0.0 in both the Destination and NetMask fields. Enter your ISP's IP address in the Gateway/NextHop field.
Note that you cannot specify the interface name, route type or route origin. These parameters are used only for routes that are identified automatically as the device communicates with other routing devices. For routes you create, the routing table displays system default values in these fields.
  1. Click Save Changes, and then click Close on the confirmation page to return to the IP Route table page. The new route should display in the table.

NOTE: If want your changes to be permanent, be sure to Write Settings to Flash.