RE: Regular expression

From: Joe A (GroupStudy@xxxxxxxxxxx)
Date: Tue Jul 09 2002 - 22:05:28 GMT-3


   
^ means 'beginning of the string', $ means 'end of the string', so ^$, with not
hing between the 2 characters, refers to an empty string bounded by the ^ and t
he $, which also means an empty AS path. The only routes that would have an em
pty AS path would be your own local routes in your own local AS, so the AS path
 filter below permits you to advertise only routes with an empty AS path, there
fore only your own local routes are sent to that neighbor. No other prefixes a
re advertised.

Joe

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Robert Yee
Sent: Tuesday, July 09, 2002 7:51 PM
To: ccielab@groupstudy.com
Subject: Regular expression

Hi all,

Am I correct in my interpreation of the following regular expressions?

.* = everything
^$ = nothing

If the above is true, and I have the following in place:

neighbor x.x.x.x filter-list 1 out

ip as-path access-list 1 permit ^$

Does this mean, that I am filtering all outbound prefixes?

TIA,

Robert



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