Configure AS Path Lists

Configure an AS path list to restrict the routing information a router learns or advertises to and from a neighbor. The AS path list acts as a filter that matches AS paths.

Before you begin

You configure BGP on a VRF instance the same way you configure the GlobalRouter, except that you must use VRF Router Configuration mode and the prefix ip bgp. The VRF must have an RP Trigger of BGP.

Note

Route refresh is not currently supported on non-default VRFs.

Procedure

Enter BGP Router Configuration mode:

enable

configure terminal

router bgp
Create the path list:

ip as-list <1-1024> memberid <0–65535> <permit|deny> as-path WORD<0–1536>

Use this command for each member by specifying different member IDs.

Example

Create the path list:

Switch(config)# ip as-list 234 memberid 3456 permit as-path "5"

Variable Definitions

The following table defines parameters for the ip as-list command.


Variable	Value
<0-65535>	Specifies an integer value between 0–65535 that represents the regular expression entry in the AS path list.
`<1-1024>`	Specifies an integer value from 1–1024 that represents the AS-path list ID you want to create or modify.
<permit\|deny>	Permits or denies access for matching conditions.
`WORD<0–1536>`	Specifies the AS number as an integer value between 0–1536. Place multiple AS numbers within quotation marks (").