Users Guide

Layer 3 Routing Commands 1278
Up to 128 AS path access lists can be configured, with up to 64 statements
each. To enter the question mark within a regular expression, first enter
CTRL-V to prevent the CLI from interpreting the question mark as a request
for help.
Command History
Introduced in version 6.2.0.1 firmware.
Example
In the following example, the router is configured to reject routes received
from neighbor 172.20.1.1 with an AS path that indicates the route originates
in or passes through AS 100.
console(config)# ip as-path access-list 1 deny _100_
console(config)# ip as-path access-list 1 deny ^100$
console(config)# router bgp 1
Special Character/Symbol Behavior
asterisk * Matches zero or more sequences of the
pattern.
brackets [] Designates a range of single-character
patterns.
caret ^ Matches the beginning of the input
string.
dollar sign $ Matches the end of the input string.
hyphen - Separates the end points of a range.
period . Matches any single character, including
white space.
plus sign + Matches 1 or more sequences of the
pattern.
question mark ? Matches 0 or 1 occurrences of the
pattern.
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.