Route Map

Route maps are sophisticated policy tools that provide conditional routing decisions by combining flexible match criteria with configurable set actions, enabling complex routing policies for route redistribution, BGP path selection, and traffic engineering. They operate using sequence-based entries that define match conditions (such as prefix lists, access lists, AS paths, or communities) paired with set actions (including metric modification, next-hop assignment, community tagging, and BGP attribute manipulation). Route maps are fundamental building blocks for implementing advanced routing policies, enabling administrators to control route advertisement, path selection, and traffic flow while supporting features like conditional route filtering, multi-homed network optimization, and service provider peering policies.

By combining match criteria with set actions, route maps enable flexible, conditional routing policies for precise control over route advertisement and traffic flow.

Key Components:

• Route Map Name (name): The identifier for the route map.

• Entry Sequence Number (entries.seq): The sequence number for each route map entry.

• Operation (entries.operation): Specifies whether the entry permits or denies matched routes.

• Match Criteria (entries.match): Defines conditions for route selection (e.g., prefix-list, access-list, AS-path, community-list, interface, tag, protocol).

• Set Actions (entries.set): Specifies actions to apply to matched routes (e.g., metric, next-hop, local preference, community, AS-path prepend, tag).

• Description (entries.description): Adds descriptive text to route map entries.

Key Parameters Briefly Explained:

• name: Route map identifier.
• entries.seq: Entry sequence number.
• entries.operation: Permit or deny action.
• entries.match: Match conditions for route selection.
• entries.set: Actions applied to matched routes.
• entries.description: Entry description.

You can use these Route Map parameters to define granular and conditional routing policies. Customize match conditions and set actions to fit your network’s traffic engineering, route redistribution, and BGP path selection requirements. Adjusting these parameters lets you precisely control how routes are advertised, filtered, and preferred across your network.

The following configuration describes how to set up route maps on a Cisco IOS-XE device, including route map entries with permit/deny actions, match conditions, and set actions for advanced routing policies.

ip prefix-list CUSTOMER-PREFIXES seq 5 permit 10.0.0.0/8 le 24
ip prefix-list BACKUP-PREFIXES seq 5 permit 172.16.0.0/16 le 24
!
route-map BGP-IN-FILTER permit 10
 description Allow specific prefixes and set local preference
 match ip address prefix-list CUSTOMER-PREFIXES
 set local-preference 200
 set community 65001:100
!
route-map BGP-IN-FILTER permit 20
 description Allow remaining prefixes with default preference
 match ip address prefix-list BACKUP-PREFIXES
 set local-preference 100
!
route-map BGP-OUT-FILTER permit 10
 description Advertise internal routes with community
 match ip address prefix-list INTERNAL-ROUTES
 set as-path prepend 65001 65001
 set community 65001:200
!
route-map BGP-OUT-FILTER permit 20
 description Set next-hop for specific interfaces
 match interface GigabitEthernet0/0/1
 set ip next-hop 192.168.1.1
 set metric 100
!
route-map BGP-OUT-FILTER deny 30
 description Deny all other routes

The following YAML code defines multiple route maps on an IOS-XE device, specifying entries with sequence numbers, permit/deny operations, match criteria, and set actions for advanced routing policies.

iosxe:
  devices:
    - name: Device1
      configuration:
        route_maps:
          - name: BGP-IN-FILTER
            entries:
              - seq: 10
                operation: permit
                description: Allow specific prefixes and set local preference
                match:
                  ipv4_address_prefix_lists:
                    - CUSTOMER-PREFIXES
                set:
                  local_preference: 200
                  communities:
                    - "65001:100"
              - seq: 20
                operation: permit
                description: Allow remaining prefixes with default preference
                match:
                  ipv4_address_prefix_lists:
                    - BACKUP-PREFIXES
                set:
                  local_preference: 100
          - name: BGP-OUT-FILTER
            entries:
              - seq: 10
                operation: permit
                description: Advertise internal routes with community
                match:
                  source_protocol:
                    connected: true
                    static: true
                set:
                  as_path_prepend_as: "65001 65001"
                  communities:
                    - "65001:200"
              - seq: 20
                operation: permit
                description: Set next-hop for specific interfaces
                match:
                  interfaces:
                    - GigabitEthernet0/0/1
                set:
                  ipv4_next_hop_addresses:
                    - 192.168.1.1
                  metric_value: 100
              - seq: 30
                operation: deny
                description: Deny all other routes