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Route Map Overview

 

A route map is a set of statements that the device applies in sequential order to a route. Each statement in the route map defines a condition that is compared to the route. A route is compared to each statement in a specified route map in order of increasing sequence number until there is a match, then the action specified by the statement is applied. If the route matches the condition in the route map statement, the route is either permitted or rejected.

A route map statement can also modify certain attributes of a matching route. There is an implicit deny at the end of every route map; that is, if a route does not match any entry in the route map, the route is rejected.

For each match condition, you specify whether a route that matches the condition is accepted (permitted) or rejected (denied). If a route matches a condition and is permitted, you can optionally set attribute values for the route. You can configure additional entries for the same route map, specifying a different sequence number for each entry.

Route Map Match Conditions

The match conditions that can be configured for a route map are displayed in Table 1.

Table 1: Route MAP Match Conditions

Property

Description

AS Path (BGP)

Select the AS path access list a route must match.

Community (BGP)

Select the community a route must match.

Metric

Select the route metric a route must match.

Interface

Select the interfaces a route must match.

Access List

Select the access list a route must match.

Next-Hop

Match a specified access list. It also supports IPv6, from ScreenOS 6.3.

Route Type (OSPF)

Select the route types (OSPF internal, external type 1, or external type 2) that a route must match.

Tag

Select the route tag value a route must match.

Permitted Route Attributes

The attributes that be configured for matching permitted routes are displayed in Table 2.

Table 2: Permitted Route Attributes

Property

Description

AS Path (BGP)

Prepends a specified AS path access list to the path list attribute of the matching route.

Community (BGP)

Sets the community attribute of the matching route to the specified community list.

Next-Hop

Sets the next-hop of the matching route to the specified IP address.

Tag

Sets the tag of the matching route to the specified tag value or IP address.

Weight

Sets the weight of the matching route.

Metric Type (OSPF)

Sets the OSPF metric type of the matching route to either external type 1 or external type 2.

Local Preference (BGP)

Sets the local-pref attribute of the matching route to the specified value.

Preserve preference (ScreenOS 5.1 and later only)

Preserves the preference value of the matching route that is exported into another virtual router.

Metric

Configures how the virtual router assigns a metric to permitted routes (select one):

  • Use Metric Specified By User as Imported/Exported Route Metric—When enabled, the VR assigns the specified metric value to all matching routes.

  • Use the Source Route Metric as the Imported/Exported Route Metric—When enabled, the VR preserves the metric of a matching route that is imported or exported into another virtual router.

  • Offset Metric (ScreenOS 5.1 and higher only)—When enabled, the VR increments the metric of the matching route by the specified number. Use this option to increase the metric on a less desirable path. For RIP routes, you can apply the increment to either routes advertised (route-map out) or routes learned (route-map in). For other routes, you can apply the increment to routes that are exported into another virtual router.

For instructions on configuring virtual router route maps, see the Network and Security Manager Online Help.