Hi, Sorry for pick up the historic thread. But why not a more simple and clear one? ip as-path access-list 1 permit ^[0-9]+$ ip as-path access-list 2 permit ^([0-9]+) ([0-9]+)$ ip as-path access-list 3 permit ^([0-9]+) ([0-9]+)([0-9]+)$ ip as-path access-list 4 permit .* It's quite clear, and you can expand it to whichever level you want. Correct me if i were wrong. regards, Yu Ning ------------------------------------------- (Mr.) Yu(2) Ning(2) ChinaNet Backbone Operation Networking Dep.,Datacom Bureau China Telecom.,Beijing(100088),P.R.C +86-10-66418105/66418121/66418123(fax) ------------------------------------------- ----- Original Message ----- From: "Peter T. Whiting" <pwhiting@fury.ittc.ukans.edu> To: "Ally Gudgeon" <alison.gudgeon@kingston-internet.net> Cc: <nanog@merit.edu> Sent: Friday, May 26, 2000 7:40 PM Subject: Re: Regular Expressions ......
I see two problems.
1. _ matches the beginning of the string, the end of the string, space, braces, comma, underscore or parentheses. What you probably wanted in your regexp is a normal space.
2. * matches zero or more of the previous pattern, what you probably wanted was a + (you want to force it to have at least one digit.)
Fixing either one of these will produce the results you are looking for. I recommend fixing both. Also, note that you can stack "beginning of string" or "end of string". The following produce the same result.
sho ip bgp reg ^_^^[0-9]*^^_^^_^[0-9]*$_$$ sho ip bgp reg ^_^^[0-9]*$___$__[0-9]*$$_$ sho ip bgp reg ^[0-9]*$
the point? Be careful with * and _.
pete
On Fri, May 26, 2000 at 10:07:50AM +0100, Ally Gudgeon wrote:
Hi All,
I am having a few problems getting my BGP filtering to work - and am experiencing some strange results..
I have two routers connected to a peering point, we have decided that we want to set local preferences of
110 to 1-deep AS-paths (as-path ACL 1) 100 to 2-deep AS-paths (as-path ACL 2) and 90 to 3-deep AS-paths (as-path ACL 3) and to not accept 4-deep AS-paths (as-path ACL 4)
I have the following as-path ACLs to try to set that and am using route maps.
ip as-path access-list 1 permit ^[0-9]*$ ip as-path access-list 2 permit ^[0-9]*_[0-9]*$ ip as-path access-list 3 permit ^[0-9]*_[0-9]*_[0-9]*$ ip as-path access-list 4 permit .*
This appears to have failed miserably....It is not setting local prefs correctly if they are 3-deep and have a repetition of an AS number it sees it as 4-deep If they are 4 AS's deep it doesn't apply a local preference but if it knows it from our other core router it sets a local pref of 100 but prefers the direct route?
(ALSO: If I do a sh ip bgp reg ^[0-9]*_[0-9]*$ it lists both 1-deep and 2-deep AS's....surely it should just list 2-deep?)
Any help would be greatly appreciated!......
Thanks in advance..
Ally
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