From: Bob Sinclair (bsin@xxxxxxxxx)
Date: Thu Mar 28 2002 - 23:47:37 GMT-3
Ying Chang,
Good catch! ^701 by itself means "starts with 701", and would include 7010, 7
011, 7012, etc. Looks like the underscore is a definite must:
ip prefix-list 1 permit ^701_[0-9]*$
looks like the best way to get AS 701 and its neighbors.
-Bob
----- Original Message -----
From: "ying chang" <ying_c@hotmail.com>
To: <bsin@erols.com>; <tobrien@cinci.rr.com>
Cc: <ccielab@groupstudy.com>
Sent: Thursday, March 28, 2002 9:30 PM
Subject: Re: AS-path access-list
> Hi,
>
> Can someone explain why sh ip bgp regexp ^701 ?[0-9]*$ pick up 7018? It
> looks like sh ip bgp regexp ^701 [0-9]*$ is the only correct way to do it
> after all.
>
> Thanks,
> Chang
>
> route-views.oregon-ix.net>sh ip b regexp ^701_?[0-9]*$
> BGP table version is 876196, local router ID is 198.32.162.100
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
> internal
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
> Network Next Hop Metric LocPrf Weight Path
> *> 3.0.0.0 157.130.185.17 0 701 80 i
> *> 3.18.135.0/24 192.205.31.33 0 7018 ?
> * 157.130.185.17 0 701 7018 ?
> * 4.0.0.0 157.130.185.17 0 701 1 i
> * 6.0.0.0/20 157.130.185.17 0 701 3549 i
> *> 9.2.0.0/16 157.130.185.17 0 701 i
> *> 9.184.112.0/20 157.130.185.17 0 701 3786 i
> *> 9.186.144.0/20 157.130.185.17 0 701 3786 i
> *> 12.0.0.0 192.205.31.33 0 7018 i
> * 157.130.185.17 0 701 7018 i
> * 12.0.252.0/23 157.130.185.17 0 701 16927 i
> *> 12.3.80.0/22 157.130.185.17 0 701 10998 i
> *> 12.3.194.0/24 157.130.185.17 0 701 6347 i
> *> 12.3.217.0/24 157.130.185.17 0 701 16666 i
> * 12.4.125.0/24 157.130.185.17 0 701 1239 i
> *> 12.4.126.0/23 157.130.185.17 0 701 17024 i
> * 12.5.201.0/24 157.130.185.17 0 701 23060 i
> *> 12.5.202.0/24 157.130.185.17 0 701 22474 i
> --More--
>
> route-views.oregon-ix.net>sh ip b regexp ^701 ?[0-9]*$
> BGP table version is 876420, local router ID is 198.32.162.100
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
> internal
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
> Network Next Hop Metric LocPrf Weight Path
> *> 3.0.0.0 157.130.185.17 0 701 80 i
> *> 3.18.135.0/24 192.205.31.33 0 7018 ?
> * 157.130.185.17 0 701 7018 ?
> * 4.0.0.0 157.130.185.17 0 701 1 i
> * 6.0.0.0/20 157.130.185.17 0 701 3549 i
> *> 9.2.0.0/16 157.130.185.17 0 701 i
> *> 9.184.112.0/20 157.130.185.17 0 701 3786 i
> *> 9.186.144.0/20 157.130.185.17 0 701 3786 i
> *> 12.0.0.0 192.205.31.33 0 7018 i
> * 157.130.185.17 0 701 7018 i
> * 12.0.252.0/23 157.130.185.17 0 701 16927 i
> *> 12.3.80.0/22 157.130.185.17 0 701 10998 i
> *> 12.3.194.0/24 157.130.185.17 0 701 6347 i
> *> 12.3.217.0/24 157.130.185.17 0 701 16666 i
> * 12.4.125.0/24 157.130.185.17 0 701 1239 i
> *> 12.4.126.0/23 157.130.185.17 0 701 17024 i
> * 12.5.201.0/24 157.130.185.17 0 701 23060 i
> *> 12.5.202.0/24 157.130.185.17 0 701 22474 i
> --More--
>
>
> >From: "Bob Sinclair" <bsin@erols.com>
> >Reply-To: "Bob Sinclair" <bsin@erols.com>
> >To: "Tim O'Brien" <tobrien@cinci.rr.com>
> >CC: <ccielab@groupstudy.com>
> >Subject: Re: AS-path access-list
> >Date: Thu, 28 Mar 2002 20:07:32 -0500
> >
> >Tim,
> >
> >As you suggested, I did a telnet to:
> >ner-routes.bbnplanet.net
> >
> >and entered:
> >
> >ner-routes>sh ip b regexp ^701_[0-9]*$
> >
> >Works like a charm, and has the advantage of not having to remember Ctl-V
> >in order to enter the "?"
> >
> >Thanks!
> >
> >PS: One might also try: http://the.groovy.org/BGP/
> >for links to mirrors, telnet access.
> >
> >----- Original Message -----
> >From: "Tim O'Brien" <tobrien@cinci.rr.com>
> >To: "Bob Sinclair" <bsin@erols.com>
> >Cc: <ccielab@groupstudy.com>
> >Sent: Thursday, March 28, 2002 7:48 PM
> >Subject: RE: AS-path access-list
> >
> >
> > > You can test it at ner-routes.bbnplanet.net
> > >
> > > Tim
> > > 9015
> > >
> > >
> > > -----Original Message-----
> > > From: Bob Sinclair [mailto:bsin@erols.com]
> > > Sent: Thursday, March 28, 2002 7:43 PM
> > > To: Tim O'Brien
> > > Cc: ccielab@groupstudy.com
> > > Subject: Re: AS-path access-list
> > >
> > >
> > > Tim,
> > >
> > > Based on my reading or Halabi, the two statements seem equivalent:
> > >
> > > ip as-path access-list 4 permit ^200_[0-9]*$
> > >
> > > and
> > >
> > > ip as-path access-list 4 permit ^200 ?[0-9]*$
> > >
> > > The underscore can mean most anything, including end of string. So it
> >would
> > > match ^200$ to identify routes from the immediate neighbor.
> > >
> > > The underscore can also be a space, then [0-9]*$ should match any
> >number
> > > (including zero) of consecutive numerals. Looks to me like both would
> >work.
> > > The first example may be easier to remember, but I would want to test it
> > > before betting $1,250 on it! I know Halabi's works.
> > >
> > > -Bob
> > >
> > >
> > > ----- Original Message -----
> > > From: "Tim O'Brien" <tobrien@cinci.rr.com>
> > > To: "Bob Sinclair" <bsin@erols.com>; "Hongtu Wang"
> ><hwang1073@rogers.com>
> > > Cc: <ccielab@groupstudy.com>
> > > Sent: Thursday, March 28, 2002 7:29 PM
> > > Subject: RE: AS-path access-list
> > >
> > >
> > > > I found this one on the Cisco site. What do you think?
> > > >
> > > > ip as-path access-list 4 permit ^200_[0-9]*$
> > > >
> > > > http://www.cisco.com/warp/public/459/41.shtml#2
> > > >
> > > > Tim
> > > > 9015
> > > >
> > > >
> > > > -----Original Message-----
> > > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> > > > Bob Sinclair
> > > > Sent: Thursday, March 28, 2002 6:37 PM
> > > > To: Hongtu Wang
> > > > Cc: ccielab@groupstudy.com
> > > > Subject: Re: AS-path access-list
> > > >
> > > >
> > > > Hongtu,
> > > >
> > > > I believe you will find that the following expression will work with
> >the
> > > > fewest number of statements to define "routes from AS 200 and its
> > > > neighbors":
> > > >
> > > > ip as-path access-list 4 permit ^200 ?[0-9]*$
> > > >
> > > > It is discussed in detail in Halabi's book "Internet Routing
> > > Architectures",
> > > > on page 376. The meaning of regular expression characters is
> >explained on
> > > > page 187.
> > > >
> > > > -Bob
> > > >
> > > >
> > > >
> > > > ----- Original Message -----
> > > > From: "Hongtu Wang" <hwang1073@rogers.com>
> > > > To: <ccielab@groupstudy.com>
> > > > Sent: Monday, March 25, 2002 10:29 PM
> > > > Subject: AS-path access-list
> > > >
> > > >
> > > > > Hi,
> > > > >
> > > > > My topology is:
> > > > >
> > > > > R1(AS100)----R2(AS200)----AS50---AS250
> > > > >
> > > > > If I only want to accept routes come from AS200 and all AS directly
> > > > connect to AS200 (AS50 in my topology), how to write as-path
> >access-list
> > > on
> > > > R1?
> > > > >
> > > > > Thanks
> > > > >
> > > > > Hongtu Wang
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