Reference Guide

254 | Access Control Lists (ACL)
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deny
e
Create a filter to drop routes that match the route’s AS-PATH attribute. Use regular expressions to
identify which routes are affected by the filter.
Syntax
deny as-regular-expression
To remove this filter, use the no deny as-regular-expression command.
Parameters
Defaults
Not configured
Command Modes
AS-PATH ACL
Usage
Information
The regular expression must match part of the ASCII-text in the AS-PATH attribute of the BGP route.
Command
History
ip as-path access-list
e
Enter the AS-PATH ACL mode and configure an access control list based on the BGP AS_PATH
attribute.
Syntax
ip as-path access-list as-path-name
To delete an AS-PATH ACL, use the no ip as-path access-list as-path-name command.
Parameters
Defaults
Not configured
Command Modes
CONFIGURATION
as-regular-expression
Enter a regular expression to match BGP AS-PATH attributes.
Use one or a combination of the following:
• . = (period) matches on any single character, including white space
• * = (asterisk) matches on sequences in a pattern (zero or more
sequences)
• + = (plus sign) matches on sequences in a pattern (one or more
sequences)
• ? = (question mark) matches sequences in a pattern (0 or 1 sequences).
You must enter an escape sequence (CNTL+v) prior to entering the
? regular expression.
• [ ] = (brackets) matches a range of single-character patterns.
• ^ = (caret) matches the beginning of the input string. (If the caret is used
at the beginning of a sequence or range, it matches on everything BUT
the characters specified.)
• $ = (dollar sign) matches the end of the output string.
• _ = (underscore) matches a comma (,), left brace ({), right brace (}), left
parenthesis, right parenthesis, the beginning of the input string, the end
of the input string, or a space.
• | = (pipe) matches either character.
Version 8.1.1.0 Introduced on E-Series ExaScale
pre-Version 6.1.1.0 Introduced for E-Series
as-path-name
Enter the access-list name, up to 140 characters.