From: marvin greenlee (marvin@ccbootcamp.com)
Date: Thu Feb 24 2005 - 00:01:05 GMT-3
"... 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."
(Where to find this on the docCD)
Cisco IOS Release 12.2 Configuration Guides and Command References
- Terminal Services Configuration Guide - Appendixes - Regular Expressions
-
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fter
sv_c/ftsappx/tcfaapre.htm
Also, check out this CCO Doc.
Cisco - Using Regular Expressions in BGP -
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094a92
.shtml
Marvin Greenlee, CCIE#12237, CCSI# 30483
Network Learning Inc
marvin@ccbootcamp.com
www.ccbootcamp.com (Cisco Training)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
ccie2be
Sent: Wednesday, February 23, 2005 6:03 PM
To: mgrenham@eircom.net; ccielab@groupstudy.com
Subject: RE: as path filtering [bcc][faked-from]
Importance: Low
No, they aren't the same.
The caret means start of string. Therefore, only 65109 can be matched.
The underscore means blank and some other stuff - I forget. So, the
difference is that with _65109$ your as-path filter will match all paths
where 65109 is the originating AS. So if the as path looks like this:
100 200 65109 matches ip as-path access-list 6 permit _65109$
200 65109 matches ip as-path access-list 6 permit _65109$
65109 only matches ip as-path access-list 5 permit ^65109$
HTH, Tim
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
mgrenham@eircom.net
Sent: Wednesday, February 23, 2005 8:43 PM
To: ccielab@groupstudy.com
Subject: as path filtering
Hi Group,
can anybody explain the difference between the below AS path filters. I
understand that the _65109$ represents prefixes originated in AS 65109 but
what about ^65109$ ?? Are they the same?
Ollie
ip as-path access-list 5 permit ^65109$
ip as-path access-list 6 permit _65109$
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