From: Donny MATEO (donny.mateo@sg.ca-indosuez.com)
Date: Thu Oct 24 2002 - 22:47:31 GMT-3
Jason,
woudn't your solutions works only under the condition those AS are directly connected.
If those AS(s) are behind another AS the AS-path would look something like xxx yyy 123 and your
solutions won't work. If the statement is to filter as-path originated from certain AS, I would go
with _123$ rather than an exact match ^123$ to cover that posibility.
Do correct me if I'm wrong.
Donny
Jason Sinclair
<sinclairj@powert To: "'Hamele Kassa'" <hkassa@attrmc.net>, ccna instructor <ccna20877@yahoo.com>,
el.com.au> ccielab@groupstudy.com
Sent by: cc:
nobody@groupstudy Subject: RE: BGP as-path filter
.com
25-10-2002 09:04
Please respond to
Jason Sinclair
The reason I used the anchors ^ and $ was that the question stated "to allow
routes originated from the following ASNs....". This is an important part of
the lab exam - understanding the question. In this case it was explicitly
stated "originated from", hence the correct answer would have to be:
Ip as-path access-list 1 permit ^123$
Ip as-path access-list 1 permit ^234$
Ip as-path access-list 1 permit ^345$
Ip as-path access-list 1 permit ^567$
Ip as-path access-list 1 permit ^678$
Ip as-path access-list 1 permit ^990$
Ip as-path access-list 1 permit ^2345$
Ip as-path access-list 1 deny .*
That said, there may be a case where the paths are prepended with the same
AS, in which cas you would have to allow multiple occurrences of the same
AS.
Cheers,
Jason Sinclair CCIE #9100
Manager, Network Control Centre
POWERTEL
55 Clarence Street,
SYDNEY NSW 2000
AUSTRALIA
office: + 61 2 8264 3820
mobile: + 61 416 105 858
email: sinclairj@powertel.com.au
-----Original Message-----
From: Hamele Kassa [mailto:hkassa@attrmc.net]
Sent: Friday, 25 October 2002 09:37
To: ccna instructor; ccielab@groupstudy.com
Subject: Re: BGP as-path filter
Try this if all the originating AS's is the BGP neighbor router
Ip as-path access-list 1 permit ^123$
Ip as-path access-list 1 permit ^234$
Ip as-path access-list 1 permit ^345$
Ip as-path access-list 1 permit ^567$
Ip as-path access-list 1 permit ^678$
Ip as-path access-list 1 permit ^990$
Ip as-path access-list 1 permit ^2345$
Ip as-path access-list 1 deny .*
or if not
Ip as-path access-list 1 permit _123$
Ip as-path access-list 1 permit _234$
Ip as-path access-list 1 permit _345$
Ip as-path access-list 1 permit _567$
Ip as-path access-list 1 permit _678$
Ip as-path access-list 1 permit _990$
Ip as-path access-list 1 permit _2345$
Ip as-path access-list 1 deny .*
----- Original Message -----
From: "ccna instructor" <ccna20877@yahoo.com>
To: <ccielab@groupstudy.com>
Cc: <sadiq.sadiq@intelsat.com>
Sent: Wednesday, October 23, 2002 11:11 PM
Subject: BGP as-path filter
> Need a AS-Path filter that is going to allow routes originated from
> following ASNs
> 123, 234, 345, 567, 678, 990, 2345
>
> Any help appreciated
> regards
> sadiq
>
>
>
>
> ---------------------------------
> Do you Yahoo!?
> Y! Web Hosting - Let the expert host your web site
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