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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Regular Expressions ......
At 06:40 26/05/00 -0500, Peter T. Whiting wrote: > > >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 _. Be careful with too complex regeg's cuz you may be the only one who understands what it is to do and once you leave [and we all know the state of documenting as-path lists on each router] no one is gonna know what your intention was with such an as-path filter. -Hank > >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 >> >> >> email - [email protected] >> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ >> This email and any files transmitted with it are confidential and intended >> solely for the use of the individual or entity to whom they are addressed. >> The views expressed in the email and files transmitted with it are those of >> the individual, not the company. If you have received this email in error >> please notify [email protected] >> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ >> >> >> > >
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