Cisco NCS 5500 Series Configuration Manuals page 148

as-path-set
Both of these policies are functionally equivalent, but the inline form does not require the configuration of
the community set just to store the six values. You can choose the form appropriate to the configuration
context. In the following sections, examples of both the named set version and the inline form are provided
where appropriate.
as-path-set
An AS path set comprises operations for matching an AS path attribute. The only matching operation is a
regular expression match.
Named Set Form
The named set form uses the ios-regex keyword to indicate the type of regular expression and requires single
quotation marks around the regular expression.
The following is a sample definition of a named AS path set:
as-path-set aset1
ios-regex '_42$',
ios-regex '_127$'
end-set
This AS path set comprises two elements. When used in a matching operation, this AS path set matches any
route whose AS path ends with either the autonomous system (AS) number 42 or 127.
To remove the named AS path set, use the no as-path-set aset1 command-line interface (CLI) command.
Note
Regular expression matching is CPU intensive. The policy performance can be substantially improved by
either collapsing the regular expression patterns together to reduce the total number of regular expression
invocations or by using equivalent native as-path match operations such as 'as-path neighbor-is', 'as-path
originates-from' or 'as-path passes-through'.
Inline Set Form
The inline set form is a parenthesized list of comma-separated expressions, as follows:
(ios-regex '_42$', ios-regex '_127$')
This set matches the same AS paths as the previously named set, but does not require the extra effort of
creating a named set separate from the policy that uses it.
community-set
A community-set holds community values for matching against the BGP community attribute. A community
is a 32-bit quantity. Integer community values must be split in half and expressed as two unsigned decimal
integers in the range from 0 to 65535, separated by a colon. Single 32-bit community values are not allowed.
The following is the named set form:
Routing Configuration Guide for Cisco NCS 5500 Series Routers, IOS XR Release 6.3.x
136
Implementing Routing Policy