[c-nsp] Sizing a router for full feed (once and for all)

[Justin M. Streiner]

On Mon, 17 Apr 2006, Kim Onnel wrote:

> If you decide that your router can will accept the two, you may not like its
> performance if you configured policy routing, QoS, Netflow, NAT, RPF,
> ACL.....
>
> But if i assume you are an ISP that only wants to give the table to a
> customer of yours, who will also get the BGP table from another provider as
> well, then you will only need to know if it will take it (memory
> requirement) and the customer need to worry about the rest, then you have a
> not-so hard home work.
>
> I looked at cisco.com, got no straight answer.

The standard answer in situations like this is often "it depends", and 
many of the features and protocols you mentioned above are reasons why 
that is often the answer.

My general rule of thumb for BGP speaking ISP routers is that whatever 
platform you use, load it up with as much RAM and flash as it can handle 
up front.  If that maximum is less than double what you have in the box
today and you're running into memory-based limitations, it's time to look 
at a platform upgrade.

TCAM limitations are another story :-)

jms