ip as-path access-list

Syntax

ip as-path access-list accessListName { permit | deny } pathExpression

no ip as-path access-list accessListName [ { permit | deny } pathExpression ]

Release Information

Command introduced before JunosE Release 7.1.0.

Description

Defines a BGP-related access list. You can specify an access list filter on both inbound and outbound BGP routes. Each filter is an access list based on regular expressions. If the regular expression matches the representation of the AS path of the route as an ASCII string, then the permit or deny condition applies. The AS path does not contain the local AS number. The no version removes a single access list entry if permit or deny and a pathExpression are specified. Otherwise, the entire access list is removed.

Options

• accessListName—Name of the access list; a string of up to 32 characters
• permit—Permits access for matching conditions
• deny—Denies access to matching conditions
• pathExpression—Regular expression describing the AS paths to be matched

  Use a sequence of one or more elements, each of which is either an AS number or one of the following punctuation characters:

  • ^ start of the path
  • $ end of the path
  • { start of an AS_SET
  • } end of an AS_SET
  • ( start of an AS_CONFED_SET or AS_CONFED_SEQ
  • ) end of an AS_CONFED_SET or AS_CONFED_SEQ

  Use the following regular expression metacharacters to match individual elements:

  • . matches any single element
  • * matches zero or more occurrences of any element
  • + matches one or more occurrences of any element
  • [ ] matches any elements enclosed between brackets ([ ])
  • - hyphen; used within brackets to specify a range of AS numbers
  • ^ matches any AS number except the ones specified when used as a first item within brackets
  • _ underscore; used in implementations on routers from other vendors on either side of a path to specify a literal and disallow substring matching. Allowed but not required in our CLI.

Mode

Global Configuration