[c-nsp] Core-network upgrade recommendation needed

[Rick Ernst]

I'm running into a memory exhaustion problem on our core network;
apparently directly related to BGP table growth.

Network is edge/core/aggregation.  The edge is basically media converters
for our upstreams (currently 3x OC-3, with growth to > 300mbs each
expected within the year).  The edge handles BGP peering and then has
redundant connections to the core via OSPF.  The core is an RR-server. 
It, in turn, feeds multiple aggregation services (DSL, ethernet MAN and
colocation, DS-3) on over a dozen devices.

The edge is 7206VXR-G1s with 1GB RAM.  Core is 7507/RSP-8 with 256MB and
GEIP+ with 256MB.  Aggregation has Redback SMS, 7513/RSP-4/256MB, Cat
5500/RSM and other devices.  My upgrade to this configuration was about 6
years ago, when I had two 7206 non-VXR, NPE-225 running everything.

256MB is no longer enough memory (~15MB free, ~40MB free after pruning /24
routes).  Recommendations for the platform I should be looking for to
handle 4x GE links (redundant up/down-links) pushing about 400Mbs
(aggregate) each, 512MB or 1GB of RAM, and basic L3 + BGP?

My first-pass guess is a 6500/7600 chassis with current Supervisors.

Thanks,
Rick