[54821] in North American Network Operators' Group
Re: As-Path filtering based on ranges, not regex
daemon@ATHENA.MIT.EDU (Brett Frankenberger)
Fri Jan 17 12:53:35 2003
Date: Fri, 17 Jan 2003 11:53:02 -0600
From: Brett Frankenberger <rbf@rbfnet.com>
To: Andy Johnson <andyjohnson@ij.net>
Cc: Vincent Gillet <vgi@zoreil.com>, nanog@merit.edu
In-Reply-To: <005e01c2be4b$681dc000$a7a616cf@andyj>
Errors-To: owner-nanog-outgoing@merit.edu
On Fri, Jan 17, 2003 at 12:10:59PM -0500, Andy Johnson wrote:
>
> Vincent,
>
> I'm fairly certain it can match a range, just as you yourself posted you
> could do. There is no difference between using a range to find 0-9, than
> there is finding 64512-65535.
There is in regular expressions.
>So your line would look something like this:
>
> ip as-path access-list 150 permit _[64512-65535]$
[0123] is a one-character regular expression matching the digit 0, 1,
2, or 3.
[3-5] is a one-character regular expression matching 3, 4, or 5.
[64512-65535] is a one-character regular expression matching
1,2,3,4,5 or 6. (It's way more complex than it needs to be, of course.
You've got 6 listed in there twice; five is listed 4 times and also
included in the 2-6 range, and so on.)
So your expression above is going to match paths ending with AS 1, 2,
3, 4, 5, or 6.
-- Brett
