Configuring Generated Routes (NSM Procedure)

Generated routes are used as routes of last resort. A packet is forwarded to the route of last resort when the routing tables have no information about how to reach that packet’s destination. One use of route generation is to create a default route to use if the routing table contains a route from a peer on a neighboring backbone network. A generated route becomes active when it has one or more contributing routes. A contributing route is an active route that is a specific match for the generated destination.

For example, for the destination 128.100.0.0/16, routes to 128.100.192.0/19 and 128.100.67.0/24 are contributing routes, but routes to 128.0.0.0./8, 128.0.0.0/16, and 128.100.0.0/16 are not. A route can contribute only to a single generated route. However, an active generated route can recursively contribute to a less specific matching generated route. For example, a generated route to the destination 128.100.0.0/16 can contribute to a generated route to 128.96.0.0/13. By default, when generated routes are installed in the routing table, the next hop device selects from the primary contributing route.

To configure generated routes in NSM:

  1. In the navigation tree, select Device Manager > Devices .
  2. In the Devices list, double click the device to select it.
  3. Click the Configuration tab.
  4. In the configuration tree, expand Routing Options.
  5. Select Generate.
  6. Add or modify the parameters as specified in Table 46.
  7. Click one:
    • OK—To save the changes.
    • Cancel—To cancel the modifications.
    • Apply—To apply the routing option settings.

Note: After you make changes to a device configuration, you must push that updated device configuration to the physical security device for those changes to take effect. You can update multiple devices at one time. See the Updating Devices section in the Network and Security Manager Administration Guide for more information.

Table 46: Generated Routes Fields

Option

Function

Your Action

Comment

Specifies the comment for the generated route.

Enter a comment.

Defaults

Enables you to specify globally generated route options. These are treated as global defaults and apply to all the generated routes you configure.

  1. Expand the Generate tree and select Defaults.
  2. Configure the default route options.

Route

Enables you to configure individually generated routes. You can also configure globally generated route options. These options apply to the individual destination only and override any options you configured in Defaults.

  1. Expand the Generate tree and select Route.
  2. Configure the individual route options.