From: garnet ulrich (garnet.ulrich@gmx.net)
Date: Fri Apr 18 2003 - 08:20:45 GMT-3
Yes. Good point. My head is not a great regexp parser. So I did learn
something.
Thank you.
garnet
Tim Fletcher wrote:
>Garnet,
>
>Your as-path list will work just fine, as will the one you mentioned from the previous e-mail. They will both meet the requirement. Consider the following regular expression and AS path:
>
>RE: _2400_(.+_)*3500_
>AS: 2400 10 20 3500
>
>The 1st underscore matches the beginning of the string, followed by a literal 2400, and the 2nd underscore matches the space between 2400 and 10. Now you might think that the ".+_" would match "10 " for 1 match, then "20 " for a 2nd match, but it really matches "10 20 " in a single match. The reason is that regular expressions are "greedy", meaning they will match as many charters as they can. So in this case, it will match everything up to a space followed by the literal 3500. So in reality, any of the following will work the same.
>
>_2400_(.*_)*3500_
>_2400_(.+_)*3500_
>_2400_(.*_)?3500_
>
>You just have to make sure you allow for any length string in the middle, followed by a space, and that the middle section is optional.
>
>-Tim Fletcher
>
>At 05:52 PM 4/16/03 -0400, Garnet Ulrich wrote:
>
>
>>I just tested this stuff and what I found is that even if you enter
>>separate
>>
>>match as-path x
>>match as-path y
>>
>>statements in your route-map, they get automatically converted to a
>>single "match as-path x y" statement which means logical OR. I
>>confirmed that it takes it as an OR.
>>
>>The best way I could come up with to match on routes with both ASes in
>>the path was the following as-path access-list:
>>
>>ip as-path access-l 110 permit (_2400_(.+_)*3500_)|(_3500_(.+_)*2400_)
>>
>>In this example, we must find 2400 and 3500 in either order. I felt the
>>access-list below was incorrect because the (.*_)? bit meant we would
>>only match if there were zero or one other ASes between the two we care
>>about.
>>
>>Feel free to comment and maybe I'll learn something more. It does
>>strike me as odd that such a long regexp is required for something that
>>seems so straightforward at first glance.
>>
>>garnet
>>
>>On Fri, 2003-04-11 at 06:24, Ryder, Keith wrote:
>>
>>
>>>Use a route map but use "match 1 2"
>>>This will match only on as-path fiter 1 AND as-path filter 2.
>>>
>>>If you specify them seperately they will be as-path filter 1 OR as-path
>>>filter 2
>>>
>>>-----Original Message-----
>>>From: Daniel Cisco Group Study [mailto:danielcgs@imc.net.au]
>>>Sent: 11 April 2003 09:49
>>>To: OhioHondo; Daniel Cisco Group Study; ahmed_hassan@rayatelecom.net
>>>Cc: ccielab@groupstudy.com
>>>Subject: RE: regular express question
>>>
>>>
>>>I checked out the old thread again..... One solution would be:
>>>
>>>ip as-path access-list 1 _3500_(.*_)?2400_| _2400_(.*_)?3500_
>>>
>>>
>>>Not pretty....
>>>
>>>Daniel
>>>
>>>-----Original Message-----
>>>From: OhioHondo [mailto:ohiohondo@columbus.rr.com]
>>>Sent: Friday, 11 April 2003 12:09
>>>To: Daniel Cisco Group Study; ahmed_hassan@rayatelecom.net
>>>Cc: ccielab@groupstudy.com
>>>Subject: RE: regular express question
>>>
>>>
>>>This was a thread about a month ago. The following works as an OR
>>>
>>>ip as-path access-list 1 permit _3500_
>>>ip as-path access-list 2 permit _2400_
>>>
>>>route-map AND permit 10
>>> match as-path 1 ---- > this shows up as match as-path 1 2
>>> match as-path 2 in the config file!!! I tried this.
>>> set metric 5000
>>>
>>>As I recall, if the original solution follows the format suggested at the
>>>end of a long discussion. The original solution is shown below and further
>>>on in this e-mail thread.
>>>
>>>ip as-path access-list 1 permit _3550_(.*)2400_|_2400_(.*)3500_
>>>
>>>
>>>
>>>-----Original Message-----
>>>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
>>>Daniel Cisco Group Study
>>>Sent: Thursday, April 10, 2003 6:13 PM
>>>To: ahmed_hassan@rayatelecom.net
>>>Cc: ccielab@groupstudy.com
>>>Subject: RE: regular express question
>>>
>>>
>>>I believe that the as-path list will also match paths containing:
>>>
>>>"3500" and "12400"
>>>"2400" and "43500"
>>>
>>>ie the (.*) also allows other characters to appear before the 2400 or
>>>3500...
>>>
>>>Anyone agree?
>>>
>>>Why not use something simple like:
>>>
>>>ip as-path access-list 1 permit _3500_
>>>ip as-path access-list 2 permit _2400_
>>>
>>>route-map AND permit 10
>>> match as-path 1
>>> match as-path 2
>>> set metric 5000
>>>
>>>
>>>Anything wrong with this logic?
>>>
>>>Daniel
>>>
>>>
>>>-----Original Message-----
>>>From: Ram Shummoogum [mailto:rshummoo@ca.ibm.com]
>>>Sent: Friday, 11 April 2003 2:22 AM
>>>To: ahmed_hassan@rayatelecom.net
>>>Cc: ccielab@groupstudy.com
>>>Subject: Re: regular express question
>>>
>>>
>>>Try this.
>>>
>>>ip as-path access-list 1 permit _3550_(.*)2400_|_2400_(.*)3500_
>>>!
>>>route-map AND permit 10
>>> match as-path 1
>>> set metric 5000
>>>
>>>
>>>
>>>
>>>
>>>"Ahmed Hassan" <ahmed_hassan@rayatelecom.net>@groupstudy.com on 04/10/2003
>>>10:35:26 AM
>>>
>>>Please respond to "Ahmed Hassan" <ahmed_hassan@rayatelecom.net>
>>>
>>>Sent by: nobody@groupstudy.com
>>>
>>>
>>>To: <ccielab@groupstudy.com>
>>>cc:
>>>Subject: regular express question
>>>
>>>
>>>Hi GROUP ,
>>>Can any one tell me how to make a regular expression that have an logical
>>>"AND" condition , for example
>>>I wan a regular expression that will filter BGP table to get expressions
>>>contain both AS2400 and AS3500 the order is not important
>>>best regards
>>>
>>>*************************************
>>>Ahmed Hassan El-shinnawy
>>>Network Planning and configuration Engineer
>>>Raya Telecom
>>>ahmed_hassan@rayatelecom.net
>>>*************************************
>>>
>>>
>>>**********************************************************************
>>>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. If you have received this email in error please notify
>>>the system manager.
>>>This footnote also confirms that this email message has been swept by
>>>MIMEsweeper for the presence of computer viruses.
>>>www.mimesweeper.com
>>>**********************************************************************
>>>
>>>
>>>**********************************************************************
>>>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. If you have received this email in error please notify
>>>the system manager.
>>>This footnote also confirms that this email message has been swept by
>>>MIMEsweeper for the presence of computer viruses.
>>>www.mimesweeper.com
>>>**********************************************************************
>>>
>>>
>>--
>>Garnet Ulrich
>>garnet.ulrich@gmx.net
>>
>>The secret of success is honesty and fair dealing. If you can fake
>>those, you've got it made.
>>
>>[GroupStudy removed an attachment of type application/pgp-signature which had a name of signature.asc]
This archive was generated by hypermail 2.1.4 : Thu May 01 2003 - 13:35:57 GMT-3