Routing Policies
ExtremeWare XOS 11.3 Concepts Guide
282
Here are some additional examples of using regular expressions in the AS-Path statement.
The following AS-Path statement matches AS paths that contain only (begin and end with) AS number
65535:
as-path "^65535$"
The following AS-Path statement matches AS paths beginning with AS number 65535, ending with AS
number 14490, and containing no other AS paths:
as-path "^65535 14490$"
The following AS-Path statement matches AS paths beginning with AS number 1, followed by any AS
number from 2 - 8, and ending with either AS number 11, 13, or 15:
as-path "^1 2-8 [11 13 15]$"
The following AS-Path statement matches AS paths beginning with AS number 111 and ending with
any AS number from 2 - 8:
as-path "111 [2-8]$"
The following AS-Path statement matches AS paths beginning with AS number 111 and ending with
any additional AS number, or beginning and ending with AS number 111:
as-path "111 .?"
( Start of a confederation segment in the AS path
) End of a confederation segment in the AS path
Table 38: Policy regular expression examples
Attribute Regular Expression Example Matches
AS path is 1234 “1234” 1234
Zero or more occurrences of AS number 1234 “1234*” 1234
1234 1234
Start of As path set “10 12 { 34” 10 12 34 { 99
33 10 12 { 34 37
End of As path set “12 } 34” 12 } 34 56
Path that starts with 99 followed by 34 “^99 34 “ 99 34 45
Path that ends with 99 “99 $” 45 66 99
Path of any length that begins with AS numbers 4, 5,
6
“4 5 6 .*” 4 5 6 4 5 6 7 8 9
Path of any length that ends with AS numbers 4, 5, 6 “.* 4 5 6 $” 4 5 6
1 2 3 4 5 6
Table 37: AS regular expression notation (Continued)
Character Definition
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