[j-nsp] Aggregation of aggregates in BGP

[Andrew]

Hi,

I don't seem to be able to supress more specific aggregates when aggregating
(in simple).


   Access
     |
     |
Distribution
     |
     |
   Core


The access router has local pools and runs bgp, it's a cisco and aggregates
the pools so that we don't leak /32s out. This works fine.


The distribution is meant to aggregate all the Access devices, as each PoP
has a large block assigned to it, lets say a /20 or something.

The problem is that the Distribution router is advertising all the smaller
/24's from the Access routers along with the aggregated route to the rest of
it's iBGP peers. I've trawled through the juniper doco/command set, and I
can't
 find a command to force it to only advertise it's own aggregate.


This problem appears in the scenario above, all intra-AS with the
distribution
acting as a RR server for the PoP, and also occurs inter-AS, as the
aggregates
of the Distribution as being advertised to our EBGP peers. The routes from
the
Access routers aren't advertised to our eBGP peers, but this is purely
because
there of other routing policies (communities et all)

We have a workaround which is to do the same to the aggreates (ie. tag them
with
something), but this isn't the most elegant way. Has anybody else
encountered
this situation and figured out a more hygenic solution?


aggregate {
    defaults {
        as-path {
            origin igp;
            atomic-aggregate;
            aggregator <our AS> <local router ip>;
        }
    }
    route XXX/20 community [ assorted communities ];
    route XXX/20 community [ assorted communities ];
}



Thanks,

Andrew