Re: BGP regexp syntax help

From: Kruepke (lister@xxxxxxxxxxx)
Date: Wed Jun 14 2000 - 17:07:40 GMT-3


   
There must be other things in the AS_PATH than just AS600.

    ^600$ matches a string containing ONLY 600

    _600$ matches a string ending in 600 (and preceded by a separator...) This
includes a string containing only 600.

Keith

----- Original Message -----
From: "Joshua W. Watkins" <josh@mstates.com>
To: <ccielab@groupstudy.com>
Sent: Wednesday, June 14, 2000 1:33 AM
Subject: BGP regexp syntax help

When using the following config for an as-path filter to filter all
routes originating from AS600 to remote AS 500, BGP ends up denying
everyting.

router bgp 100
 no synchronization
 bgp confederation identifier 666
 neighbor 172.16.4.5 remote-as 500
 neighbor 172.16.4.5 filter-list 1 out
 neighbor 172.16.10.1 remote-as 100
 neighbor 172.16.10.1 next-hop-self
!
ip classless
ip as-path access-list 1 deny ^600$
ip as-path access-list 1 permit .*

I then change the ip as-path access-list to deny _600$ instead of deny
^600$ and BGP filters all routes originating from AS 600 and allows
everything else. Can someone explain why _600$ works and ^600$ does
not?

Thanks.

Joshua W. Watkins
Systems Engineer
Mountain States Networking



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