Re: BGP Regular Expression - logic help

From: James (james@towardex.com)
Date: Sun Jul 11 2004 - 23:42:43 GMT-3


> I think it is ^(.+_)*4(_.+)?$
>
> because ^4_[0-9]*$ will not match 3 2 1 4, or 3 2 1 4 5. This will only

_4_[0-9]*$

>
> I think + is more appropriate here than *, since AS number must have at
> least one digit in it.

+ requires minimum object match
4_[0-9]+$ will match:
 4 1 IGP
 4 3 IGP
 4 101 IGP
 etc.

and will not match:
 4 IGP

a good way to test out your regex is:
  telnet route-views.oregon-ix.net or route-server.ip.att.net

  and 'sh ip bgp reg <REGEX>'

-J

>
> Cheers,
>
> Adel Abouchaev
> CCIE# 12037
> www.netmasterclass.net
>
>
>
> Joe Deleonardo wrote:
>
> >D'OH! Light just went on.
> >
> >The * refers to what's inside the [ ]
> >
> >I was thinking it meant something more like ([0-9]*)*
> >
> >Cool! Thanks! That helped a lot!
> >
> >Cheers,
> >
> >Joe
> >
> >
> >-----Original Message-----
> >From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> >James
> >Sent: Sunday, July 11, 2004 5:45 PM
> >To: Joe Deleonardo
> >Cc: 'group study'
> >Subject: Re: BGP Regular Expression - logic help
> >
> >
> >
> >>It seems like ^4_[0-9]?$ would be what we should use to get "Only Networks
> >>Originated from AS 4, and ASs Directly Attached to AS 4" No?
> >>
> >>
> >
> >I believe ^4_[0-9]*$ should do your needs..
> >
> >
> >
> >>So what do you guys think? Am I over thinking this? Yes ^4_[0-9]*$ will
> >>
> >>
> >get
> >
> >
> >>you what you want but it seems like, you'll also get more then AS 4 and
> >>
> >>
> >it's
> >
> >
> >>directly attached networks.
> >>
> >>
> >
> >Hmm..? This seems to do it just fine. _[0-9]* means either match one more
> >asn
> >after 4, or match nothing after 4. I know it's a bit confusing :)
> >
> >output of.. sh ip bgp reg _701_[0-9]*$
> >*> 6.1.0.0/16 63.239.36.245 1923 100 0 209 701 668 i
> >*> 6.2.0.0/22 63.239.36.245 1923 100 0 209 701 668 i
> >*> 6.3.0.0/18 63.239.36.245 1923 100 0 209 701 668 i
> >*> 6.4.0.0/16 63.239.36.245 1923 100 0 209 701 668 i
> >*> 6.5.0.0/19 63.239.36.245 1923 100 0 209 701 668 i
> >*> 6.8.0.0/20 63.239.36.245 1923 100 0 209 701 668 i
> >*> 6.9.0.0/20 63.239.36.245 1923 100 0 209 701 668 i
> >*> 6.10.0.0/15 63.239.36.245 1923 100 0 209 701 668 i
> >*> 6.14.0.0/15 63.239.36.245 1923 100 0 209 701 668 i
> >*> 12.0.17.0/24 63.239.36.245 1923 100 0 209 701 26990
> >i
> >*> 12.1.235.0/24 63.239.36.245 1923 100 0 209 701 15184
> >i
> >*> 12.3.54.0/24 63.239.36.245 1923 100 0 209 701 25938
> >i
> >*> 12.3.80.0/22 63.239.36.245 1923 100 0 209 701 10998
> >i
> >*> 12.3.217.0/24 63.239.36.245 1923 100 0 209 701 16666
> >i
> >etc etc etc...
> >
> >
> >
> >
> >>You know if I had the choice of Cisco improving on any one thing - this
> >>would be it. There's got to be an easier way to catch this mouse.
> >>
> >>
> >
> >JUNOS as-path matching is a heck of a lot easier..
> >
> >-J
> >
> >
> >
> >>Thanks in advance!
> >>
> >>Joe
> >>
> >>[GroupStudy removed an attachment of type application/ms-tnef which had a
> >>
> >>
> >name of winmail.dat]
> >
> >
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-- 
James Jun                                            TowardEX Technologies, Inc.
Technical Lead                        Network Design, Consulting, IT Outsourcing
james@towardex.com                  Boston-based Colocation & Bandwidth Services
cell: 1(978)-394-2867           web: http://www.towardex.com , noc: www.twdx.net


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