From: Igor M. (imanassypov@rogers.com)
Date: Fri Sep 26 2008 - 09:30:51 ART
Just a note - the second regex will NOT allow self-prepending directly
connected customers... Here it is:
BB1#sh ip bgp regexp ^([0-9]+)?$
BGP table version is 94, local router ID is 212.18.3.1
Status codes: s suppressed, d damped, h history, * valid, > best, i -
internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*>i28.119.16.0/24 172.16.4.3 0 100 0 i
*>i28.119.17.0/24 172.16.4.3 0 100 0 i
*> 112.0.0.0 0.0.0.0 0 32768 i
*> 113.0.0.0 0.0.0.0 0 32768 i
*> 114.0.0.0 0.0.0.0 0 32768 i
*> 115.0.0.0 0.0.0.0 0 32768 i
*> 116.0.0.0 0.0.0.0 0 32768 i
*> 117.0.0.0 0.0.0.0 0 32768 i
*> 118.0.0.0 0.0.0.0 0 32768 i
*> 119.0.0.0 0.0.0.0 0 32768 i
*> 174.1.0.0 54.1.2.6 0 0 100 i
*>i174.1.3.0/24 172.16.4.3 0 100 0 100 i
*> 174.1.4.0/24 54.1.2.6 0 100 i
*>i174.1.7.0/24 172.16.4.3 0 100 0 100 i
BB1#sh ip bgp
BGP table version is 94, local router ID is 212.18.3.1
Status codes: s suppressed, d damped, h history, * valid, > best, i -
internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*>i28.119.16.0/24 172.16.4.3 0 100 0 i
*>i28.119.17.0/24 172.16.4.3 0 100 0 i
*> 112.0.0.0 0.0.0.0 0 32768 i
*> 113.0.0.0 0.0.0.0 0 32768 i
*> 114.0.0.0 0.0.0.0 0 32768 i
*> 115.0.0.0 0.0.0.0 0 32768 i
*> 116.0.0.0 0.0.0.0 0 32768 i
*> 117.0.0.0 0.0.0.0 0 32768 i
*> 118.0.0.0 0.0.0.0 0 32768 i
*> 119.0.0.0 0.0.0.0 0 32768 i
*> 174.1.0.0 54.1.2.6 0 0 100 i
*>i174.1.3.0/24 172.16.4.3 0 100 0 100 i
* 54.1.2.6 0 100 100 100 100
i
*> 174.1.4.0/24 54.1.2.6 0 100 i
*>i174.1.7.0/24 172.16.4.3 0 100 0 100 i
* 54.1.2.6 0 100 100 100 100
i
----------------------
I.M., M.Eng. P.Eng.
Network Architect
CI Investments
----------------------
--- On Fri, 9/26/08, Huan Pham <Huan.Pham@peopletelecom.com.au> wrote:
From: Huan Pham <Huan.Pham@peopletelecom.com.au>
Subject: RE: Correct AS Path
To: "Peter Hauck" <pahauck@gmail.com>, ccielab@groupstudy.com
Received: Friday, September 26, 2008, 2:41 AM
Hi Peter,
- The first one only match route from directly connected customer if
they do not do any prepending.
- The second allow route originated internally, routes from directly
connected customer (allowing to self-prepend of their own AS).
I think the second is better. If you do not want to allow internal
routes, generated by your AS, then you can do
^([0-9]+)+$
Cheers,
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Peter Hauck
Sent: Friday, 26 September 2008 4:23 PM
To: ccielab@groupstudy.com
Subject: Correct AS Path
For those who have done this in IE it may be familiar....
Create an AS filter to filter prefixes originated by AS Y's directly
connected customers. (Assumning you are on the router that is part of
ASY).
Would this mean ^[0-9]+$ or ^([0-9]+)?$
I am thinking that the first AS-PATH as it matches what is specified, as
the second also allows routes from the AS itself.
Am I wrong?
-- PeterBlogs and organic groups at http://www.ccie.net
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