From: IPSec (ipsec@xxxxxxxxxxxxx)
Date: Fri Feb 15 2002 - 04:47:54 GMT-3
right, I just don't know how Halabi came up with this ? preceded with a space?
Sean, you said ^1 ?[0-9]* would translate to "100", "1000"?
I don't think so, but it could be "1 200", "1", "1 1234" like you said.
Halabi was trying to filter adjacent AS1 and AS1's adjacent neighbor. but I thi
nk his as_path ^1 ?[0-9]*$ would also filter AS's like "12", "148", "1838", "13
904" etc., which are asked or intended to. Am I right here, Brian?
-----Original Message-----
From: "Sean Chao" <seanchao@bellatlantic.net>
To: "IPSec" <ipsec@myrealbox.com>, <brian@5g.net>
Date: Fri, 15 Feb 2002 02:33:06 -0500
Subject: Re: Re: Halabi's AS_PATH
Well, if you want "AS's from neighbor AS1 and AS1's neighbor" then maybe the
"?" shouldn't be in there.
>From my understanding, this would match things like "100", "1000", "1 200",
"1", "1 1234", etc.
^ starts off the line, <space> by itself says there has to be exactly one
space, [0-9]* means any numeric string (maybe + would be more appropriate,
at least 1 or more of those numbers), since "1 " as an as wouldn't make
sense. and a $ to finish off the string.
Sean.
----- Original Message -----
From: "IPSec" <ipsec@myrealbox.com>
To: <brian@5g.net>
Cc: <ccielab@groupstudy.com>
Sent: Friday, February 15, 2002 2:18 AM
Subject: Re: Re: Halabi's AS_PATH
> Brian, thanks for the url!
> I logged on and played a few regexp's on it.
> My understanding of ? is 0 or 1 occurance of the preceding character,
which in my question is a space.
> and * is 0 or multiple occurances, which in my question is a single digit
of 0 to 9. And ^ and $ are beginning and end of the as-Path.
> I guess what I don't understand is Halabi used it to refer any AS's from
neighbor AS1 and AS1's neighbor.
> How does that ^1 ?[0-9]*$ as_path translate to that?
>
> IPSec
>
> -----Original Message-----
> From: Brian Dennis <brian@5g.net>
> To: IPSec <ipsec@myrealbox.com>, ccielab@groupstudy.com
> Date: Thu, 14 Feb 2002 22:32:23 -0800
> Subject: Re: Halabi's AS_PATH
>
> IPSec, (if that is your real name ;-)
>
> Telnet to this route server:
>
> ner-routes.bbnplanet.net
>
> and play around with these three commands:
>
> sho ip bgp regexp ^701$
> sho ip bgp regexp ^701 ?[0-9]*$
> sho ip bgp regexp ^701_
>
> You should quickly be able to find the answer to your question.
>
>
> Brian Dennis, CCIE #2210 (R&S)(ISP/Dial)
>
>
> On Thursday 14 February 2002 09:54 pm, IPSec wrote:
> > There's multiple references to an as_path of
> > ^1 ?[0-9]*$ in Halabi's Chapter 12.
> > Could someone explain to me what that as_path means?
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