[isp-bgp] Re: multiple route maps for as-path prepend?

[Charles Gucker <cgucker@...>]

On Thu, 19 Aug 2004 11:36:44 -0500, Bob Hrbek <bhrbek@...> wrote:
> Question for the guru's or anybody that knows the answer.   I'd like to do an as-path prepend on a few subnets and not on others.   Is multiple route-maps the best way to do that?   See me below config....will this accomplish that?

yes, it will accomplish what you are looking to do, but there are some
more elegant
ways to handle things like this, but creating multiple entries in a
route-map is the way
to go.  You may want to look at using a prefix-list to catch the
addresses that will
be announced with a prepend set.  Using this method, you can pass
along communities
and other helpful information to your neighbor, but I would recommend
you think a little
more dynamically if you plan to scale this to multiple peers (without
session configurations).

If you would like some more information, hit me up off list.

thanks,
charles

> 
> =========== SNIP of config ==========
> route-map sprint_out permit 20
>  match ip address 30
>  set as-path prepend 32314 32314 32314
> 
> route-map sprint_out permit 30
>     match ip address 40
> 
> =============Full BGP config ===========
> 
> router bgp 32314
>  bgp log-neighbor-changes
>  network 204.96.188.0
>  network 204.96.189.0
>  network 204.96.190.0
>  network 204.96.191.0
>  neighbor 160.81.32.29 remote-as 1239
>  neighbor 160.81.32.29 version 4
>  neighbor 160.81.32.29 prefix-list jag-nets-out out
>  neighbor 160.81.32.29 route-map sprint_out out
> 
> ip prefix-list jag-nets-out seq 5 permit 204.96.188.0/24
> ip prefix-list jag-nets-out seq 10 permit 204.96.189.0/24
> ip prefix-list jag-nets-out seq 15 permit 204.96.190.0/24
> ip prefix-list jag-nets-out seq 20 permit 204.96.191.0/24
> 
> access-list 30 permit 204.96.189.0
> access-list 30 permit 204.96.190.0
> access-list 30 permit 204.96.191.0
> 
> access-list 40 permit 204.96.188.0
> 
> route-map sprint_out permit 20
>  match ip address 30
>  set as-path prepend 32314 32314 32314
> 
> route-map sprint_out permit 30
>     match ip address 40
> 
> Thanks,
> Bob
> 




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