[nsp] Catalyst 5000(5500) over 4000(4500)???

[warner at cats.ucsc.edu]

David said:

>The SupIII & SupIV for the 4000 series can run BGP.  The SupIII maxes
>out at 256MB RAM, the SupIV's max is 512MB.  Both have fairly fast
>processors, so you should be able to handle variety of BGP setups.

While the Sup-4 can hold lots of RAM, the number of TCAM entries
to hold forwarding entries is limited to 128K.  That limits 
unicast and multicast routes.  While you might be able to keep
from busting the CAM limit with some hand crafted bgp access
lists, you are either right at the limit for holding full internet
routes, or just over it.  RAM and TCAM limits are separate requirements
for full routes.  I asked as was told that when the number of
required TCAM entries no longer fits in the hardware, the whole
system resorts to CPU-based forwarding.  

-jim warner, UCSC