Re: BGP filtering

Hey Evan,

Both will work, but you can only have one prefix-list neighbor statement
applied. If you use the prefix-list statement all of those prefixes will be
filtered regardless of the underlying route-map as it is applied before the
route-map in the outbound direction with the route-map only applying to the
remaining prefixes. If you are just trying to use a prefix-list by itself
with no other filtering I'd use a prefix-list neighbor statement. If you are
combining methods, I suggest using a route-map neighbor statement. I hope
that helps.

On 6/23/09 8:42 PM, "Evan Weston" <evan_weston_at_hotmail.com> wrote:

> G'day all,
>
>
>
> Just wondering if there's a difference between these two methods of
> filtering besides the obvious i.e one way is a route-map and the other is a
> prefix list. I ask because some vendor workbooks seem to prefer the
> route-map method in their solution guides.
>
>
>
>
>
> ip prefix-list AGGREGATE1 seq 5 deny 2.2.0.0/22
>
> ip prefix-list AGGREGATE1 seq 10 permit 0.0.0.0/0 le 32
>
>
>
> neighbour x.x.x.x prefix-list AGGREGATE1 out
>
>
>
> ip prefix-list AGGREGATE2 seq 5 permit 2.2.0.0/22
>
> !
>
> route-map BGP_OUT deny 10
>
> match ip address prefix-list AGGREGATE2
>
> !
>
> route-map BGP_OUT permit 20
>
>
>
> neighbour x.x.x.x route-map BGP_OUT out
>
>
>
> Evan
>
>
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>
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Cheers,

Jared Scrivener CCIE3 #16983 (R&S, Security, SP), CISSP
Sr. Technical Instructor - IPexpert, Inc.
URL: http://www.IPexpert.com
Telephone: +1.810.326.1444
Fax: +1.810.454.0130
Mailto: jscrivener_at_ipexpert.com

Blogs and organic groups at http://www.ccie.net
Received on Wed Jun 24 2009 - 16:21:01 ART