RE: regular express question

From: Garnet Ulrich (garnet.ulrich@gmx.net)
Date: Wed Apr 16 2003 - 18:52:37 GMT-3

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
> *************************************
>
>
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--
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.

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