router design (was Re: /24s run amuck)

Tue Jan 13 19:35:48 UTC 2004

On Tue, Jan 13, 2004 at 02:12:13PM -0500, Craig Partridge wrote:
> 
> The basic issue here is the huge difference between a nice, dense, slow
> and relatively cool [cheap!] DRAM and very fast, not so dense, and pretty hot
> [and very expensive] SRAM.  That Dell server has DRAM.  Your route processor
> (if the router is at all fast) needs SRAM (and of the ultra-fast expensive
> variety).

You're talking about the fib, I'm talking about the rib. Lets just assume
for the sake of argument that your 8mb of sram is enough to scale to a
million routes and is not a problem (or maybe not if you want to run a
bunch of seperate routing tables, but that is an unrelated issue :P).  
There isn't really a reason why a route processor produced in the last 3
years needs sram at all.

> And, oh by the way, for good performance the route processor usually
> needs to share the same card as the link termination equipment -- those
> nice lasers, and optical termination chips -- which eat board space and
> generate heat you might otherwise budget for more route processor
> memory.

Nah. Every modern routing device worth any kind of time or attention uses
something other than software lookups off the RP, even if it's just
hacking l3 info into a switch cam. Even if there does exist a slow path
through the route processor, it is assumed that if you hit it you're
already screwed. The bandwidth necessary to distribute the forwarding
information to the cards or other forwarding components is trivial.

As far as pricing for these things goes, let us take an example here... 
The Juniper routing engine is actually a 6U blade server on it's side:

http://www.kontron.com/products/pdproductsubcategory.cfm?keyProductCategory=3&kps=681

I understand the need for compact components as space is limited, I
understand the performance limitations of using laptop components, and I
don't expect to see that kind of board upgradable to whatever processors
are out 3 years from now. But don't tell me that you can't sell the 2GHz 
model that is available today instead of the p2 333mhz or the recently 
introduced p3 600mhz, or that it costs anywhere near $20,000 for that 
blade server. :)

-- 
Richard A Steenbergen <ras at e-gerbil.net>       http://www.e-gerbil.net/ras
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)