Advanced Configuration and Management Guide

Table 10.2: BGP4 Special Characters for Regular Expressions (Continued)

Character

Operation

 

 

^

A caret (when not used within brackets) matches on the beginning of an

 

input string. For example, the following regular expression matches on an

 

AS-path that begins with “jlampa”:

 

^jlampa

 

 

 

$

A dollar sign matches on the end of an input string. For example, the

 

following regular expression matches on an AS-path that ends with “deg”:

 

deg$

 

 

 

_

An underscore matches on one or more of the following:

 

•

, (comma)

 

• { (left curly brace)

 

• } (right curly brace)

 

•

( (left parenthesis)

 

•

) (right parenthesis)

 

• The beginning of the input string

 

• The end of the input string

 

•

A blank space

 

For example, the following regular expression matches on “100” but

 

not on “1002”, “2100”, and so on.

 

_100_

 

 

 

[ ]

Square brackets enclose a range of single-character patterns. For

 

example, the following regular expression matches on an AS-path that

 

contains “1”, “2”, “3”, “4”, or “5”:

 

[1-5]

 

 

You can use the following expression symbols within the brackets. These

 

symbols are allowed only inside the brackets.

 

• ^ – The caret matches on any characters except the ones in the

 

brackets. For example, the following regular expression matches on

 

an AS-path that does not contain “1”, “2”, “3”, “4”, or “5”:

 

[^1-5]

 

• - The hyphen separates the beginning and ending of a range of

 

characters. A match occurs if any of the characters within the range is

 

present. See the example above.

 

 

A vertical bar (sometimes called a pipe or a “logical or”) separates two

 

alternative values or sets of values. The AS-path can match one or the

 

other value. For example, the following regular expression matches on an

 

AS-path that contains either “abc” or “defg”:

 

(abc)(defg)

 

Note: The parentheses group multiple characters to be treated as one

 

value. See the following row for more information about parentheses.

 

 

 

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