Users Guide

Layer 3 Routing Commands 1426
ip as-path access-list
To create an AS path access list, use the ip as-path access-list. An AS path
access list filters BGP routes on the AS path attribute of a BGP route. To
delete an AS path access list, use the no form of this command
Syntax
ip as-path access-list as-path-list-number { permit | deny } regexp
no ip as-path access-list as-path-list-number
• as-path-list-number—A number from 1 to 500 uniquely identifying the
list. All AS path access list commands with the same as-path-list-number
are considered part of the same list.
• permit—(Optional) Permit routes whose AS Path attribute matches the
regular expression.
• deny—(Optional) Deny routes whose AS Path attribute matches the
regular expression.
• regexp—A regular expression used to match the AS path attribute of a
BGP path where the AS path is treated as an ASCII string.
Default Configuration
No AS path lists are configured by default. There are no default values for any
of the parameters of this command.
Command Mode
Global Configuration
User Guidelines
The AS path attribute is a list of the autonomous system numbers along the
path to the destination. An AS path access list is an ordered sequence of
statements. Each statement specifies a regular expression and a permit or
deny action. If the regular expression matches the AS path of the route
expressed as an ASCII string, the route is considered a match and the
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