From: Alex Arseniev (alex.arseniev@gmail.com)
Date: Fri Apr 20 2007 - 12:13:15 ART
Use BGP "table-map" feature?
http://www.cisco.com/en/US/products/sw/iosswrel/ps5207/products_command_reference_chapter09186a00801dbab2.html#wp1117257
Haven't tried this myself, sorry :-(
Rgds
Alex
On 20/04/07, Geert Nijs <geert.nijs@simac.be> wrote:
>
> Hi group,
>
> I am having a bit of a problem with the following challenge:
>
> Suppose you have a router with a BGP connection. Over this BGP connection
> the following prefixes are received:
>
> 192.168.2.0 / 24
> 192.168.3.0 / 24
> 192.168.4.0 / 24
>
>
> For some specific ranges, i do not want the very specific prefixes, but i
> only want a summary to be installed into the routing table.
>
> For example: i would like to summarize the above prefixes into 192.168.0.0/ 16 and i only want
> 192.168.0.0 / 16 in my routing table.
>
> Generating the summary is not difficult:
>
> router bgp 6500
> aggregate-address 192.168.0.0 255.255.0.0 summary-only
>
> This generates the summary and supresses (in BGP !!) the specific prefixes
> (for outbound BGP advertisements)
>
> sh ip bgp
>
> *> 192.168.0.0/16
> s> 192.168.2.0
> s> 192.168.3.0
> s> 192.168.4.0
>
>
> However, in the routing table, all prefixes are still installed:
>
> 192.168.0.0 / 16
> 192.168.2.0 / 24
> 192.168.3.0 / 24
> 192.168.4.0 / 24
>
> I could filter the 192.168.x.0 / 24 prefixes inbound on the BGP session,
> so that they do not get to the BGP table,
> but this would prevent the summary from being generated, because there is
> not at least one specific route. Sort of a chicken and egg problem:
> i don't want the specific prefixes in my routing table, but i can't filter
> them off otherwise the summary isn't generated any more.......
>
> Is there a way to prevent the specific routes from being installed into
> the routing table, however, still generating the summary.....
>
> regards,
> Geert
>
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This archive was generated by hypermail 2.1.4 : Tue May 01 2007 - 08:28:36 ART