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Cisco IOS in a Nutshell, 2nd Edition by James Boney

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Name

set as-path — route-map

Synopsis

set as-path {tag | prepend as-path-string}
no set as-path {tag | prepend as-path-srting}

Configures

Properties of routes matching a route map

Default

None

Description

Route maps let you select routes based on certain criteria and modify the properties of those routes using one or more set commands. This command allows you to modify the autonomous system path for BGP routes that match the route map’s criteria. (To define a route map, use the route-map command; to specify a route map’s matching criteria, use the match command.) The set as-path command has the following arguments:

tag

When redistributing routes into BGP, converts the tag of the route directly into an autonomous system (AS) path.

prepend as-path-string

Adds the as-path-string to the beginning of any AS path.

Example

In this example, we create a route map called test-as-path. Inside the map, we match any AS path list with the number 1. We then use the set as-path command to prepend our local autonomous system (300) to all routes advertised to our neighbor (10.10.1.1).

route-map test-as-path
  match as-path 1
  set as-path prepend 300
!
ip as-path access-list 1 permit .*
!
router bgp 300
  neighbor 10.10.1.1 route-map test-as-path out

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