From: Manny Gonzalez (manny@xxxxxxx)
Date: Thu Apr 04 2002 - 02:32:46 GMT-3
Gotcha... now I get what you meant... Yes, you are absolutely correct.
This is a very handy REGEXP character.
ying chang wrote:
>
> Hi Manny,
>
> Sorry about the confusion, I'm not saying anything new. What I'm trying to
> say is when we are talking about "_300_", don't forget AS300 can be
> anywhere in the path. So we don't need to write statements like:
>
> ip as-path access-list 1 permit ^300$
> ip as-path access-list 1 permit _300$
> ip as-path access-list 1 permit ^300_
> ip as-path access-list 1 permit _300_
>
> A single statemnet
>
> ip as-path access-list 1 permit _300_
>
> would cover all.
>
> Please correct me if I'm wrong.
>
> Thanks,
> Chang
>
> >From: Manny Gonzalez <manny@nyp.org>
> >To: ying chang <ying_c@hotmail.com>
> >CC: gonzalu@nyp.org, mamoor@ieee.org, ccielab@groupstudy.com
> >Subject: Re: BGP AS-PATH
> >Date: Wed, 03 Apr 2002 22:09:29 -0500
> >
> >Ying Chang,
> >
> >I am sorry but I did not understand your response. Can you re-write your
> >post with a more descriptive explanation of what you mean? You claim
> >that "_" will match specific AS-PATH regular expressions?? I don't get
> >your intended meaning.
> >
> >I know that the underscore matches a lot of things, including beginning
> >and end of string. So what are you trying to say exactly?
> >
> >TIA
> >
> >Manny Gonzalez.....................CCIE# 9013
> >CORE Resources.......NY Presbyterian Hospital
> >
> >ying chang wrote:
> > >
> > > "_" is a tricky one, it matches ^, $, (, ), {, }, " ", ",", or "_". That
> > > means it will covers ^300$, ^300_, _300$ and _300_.
> > >
> > > Chang
> > >
> > > >From: "Manny Gonzalez" <gonzalu@nyp.org>
> > > >Reply-To: "Manny Gonzalez" <gonzalu@nyp.org>
> > > >To: Ahmed Mamoor Amimi <mamoor@ieee.org>
> > > >CC: ccielab@groupstudy.com
> > > >Subject: Re: BGP AS-PATH
> > > >Date: Wed, 03 Apr 2002 18:15:15 -0500
> > > >
> > > >Well, all look okay except:
> > > >
> > > > > ^300$ = orignating from 300
> > > >
> > > >I believe this actually means from the CONNECTED AS 300, not ORIGINATED
> > > >from there... for ORIGINATED in AS300 I believe you would do
> > > >
> > > >_300$
> > > >
> > > >The other one is
> > > >
> > > > > ^300 200$ = routes from AS 300 and 200 or 200 and 300
> > > >
> > > >I believe you also have this one incorrectly interpreted. I believe it
> > > >actually means that the PATH MUST BE 300 200 in exactly that order. For
> > > >200 300 you would need ^200 300$. I believe it is a literal expresion.
> > > >
> > > >If I am wrong I will be corrected soon enough.
> > > >
> > > >Also, I would be careful with your interpretation of forward or
> > > >backwards paths... Let's say we stay on the same ballpark and use
> >common
> > > >terminology. I prefer the term ORIGINATE and TRANSIT and CONNECTED as
> > > >descriptive terms in an as-path. We all agree that the origin is at the
> > > >righ hand side of the string and the connected AS is always on the left
> > > >hand side of the string... etc. etc. :-))
> > > >
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