ip as-path

Unanswered Question
Oct 15th, 2007
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I was looking over a router config when I ran across the following:

ip as-path access-list 17 permit ^[0-9]+$

ip as-path access-list 17 permit ^$

what is the meaning of this I tried looking it up but maybe I'm not understanding what I read....sorry for the silly question

Thank you warren

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Overall Rating: 5 (3 ratings)
cisconoobie Mon, 10/15/2007 - 10:54
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(ip as-path access-list 17 permit ^$) is used for bgp updates sent to peers.

There should be a router bgp route-map associated with this.

Means all networks originating from your AS and no others, protects your AS from becomming a transit-as.

The other command, I'm not exactly sure, have to do the math.

Haris P Mon, 10/15/2007 - 11:23
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the statement ^[0-9]+$ will match bgp routes originated from next upstream ....that's with AS-path length 1 , the next statement ^$ is will match the routes originated by the router... So The as-path 17 will be a summary of routes originated from next upstream and routes originated by the router



wgranada1 Tue, 10/16/2007 - 08:38
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Thank you all for the info it was very helpfull and thank you Haris for the explaination!!!


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