From: Ray (ray.armstrong@xxxxxxxxxxxxxxxxxx)
Date: Fri Mar 29 2002 - 11:57:38 GMT-3
Doyle Vol II, has a good concise explanation with examples of regular
expressions in appendix B if you have it.
RA.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
GerbCraig
Sent: 29 March 2002 14:37
To: ying chang; bsin@erols.com
Cc: ccielab@groupstudy.com
Subject: Re: AS-path access-list
In order to filter on an AS and any AS that is attached to it you must first
include the AS itself and then the AS and its connected AS
i.e.:
ip prefix-list 1 permit ^701$ (permits the AS 701)
ip prefix-list 1 permit ^701_[0-9]*$ (permits AS 701 and any combination of
AS that may be attached to the 701 AS)
----- Original Message -----
From: "ying chang" <ying_c@hotmail.com>
To: <bsin@erols.com>
Cc: <ccielab@groupstudy.com>
Sent: Thursday, March 28, 2002 10:55 PM
Subject: Re: AS-path access-list
> Bob,
>
> I think "_" or " " will give us the same result in this case. Actually,
> ^701_[0-9]*$, ^701 [0-9]*$, ^701_([0-9]*)?$, or ^701 ([0-9]*)?$ all
returned
> the same result when I tried them earlier.
>
> Come to think about it, here is what I think how we get 7018:
>
> "?" is match 0 or 1 occurrences of the pattern. When "?" is equal to 0, we
> will get 701[0-9]*, whether we are using "_" or " ". Baically we got
> "^701_[0-9]*$" and "^701[0-9]*$" in our case.
>
> Learn new thing every day.
>
> Thanks,
> Chang
>
>
> >From: "Bob Sinclair" <bsin@erols.com>
> >To: "ying chang" <ying_c@hotmail.com>
> >CC: <ccielab@groupstudy.com>
> >Subject: Re: AS-path access-list
> >Date: Thu, 28 Mar 2002 21:47:37 -0500
> >
> >Ying Chang,
> >
> >Good catch! ^701 by itself means "starts with 701", and would include
> >7010, 7011, 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
> > > > > > >
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 10:57:25 GMT-3