BGP Aggregation question

From: Geert Nijs (Geert.Nijs@simac.be)
Date: Thu Oct 16 2008 - 09:03:42 ART


Hi group,

----OSPF----|ROUTER|----BGP

I receive both from OSPF and from BGP routes in the 10.0.0.0/8 range.

Lets say: 10.10.0.0/16 (and smaller) from OSPF and 10.20.0.0/16 (and smaller) from BGP

OSPF is redistributed into BGP.
So in the BGP table, both ranges are present.

I would like to generate an aggregate route in BGP to summarize all 10.0.0.0/8 networks.

However, this aggregate can only be based on the BGP received routes. The OSPF 10.10.0.0/16 range should not count (or be considered) in generating the aggregate.
The goal is that if the BGP session should fail, the aggregate should disappear (even if there are still OSPF routes present in the range of the aggregate).

I thought about something like:

-----------------------------------------------
router bgp xxxx
   aggregate-address 10.0.0.0 255.0.0.0 suppress-map SUPROUTES

ip prefix-list OSPFROUTES seq 10 permit 10.10.0.0/16 le 32

route-map SUPROUTES permit 10
 match ip address prefix-list OSPFROUTES
--------------------------------------------------

However, this doesn't work. The suppress-map -only- supresses the advertisement of the more specific routes, the routes
are still taken into account for generating the aggregate.
If i shut the BGP session, the aggregate is still installed.

Is there a way to just -completely ignore- 'some' routes when generating an aggregate ?

regards,
Geert

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