Re: Command Queue Depth (was asymmetric/Symmetric)

[Michael Krause <krause@cup.hp.com>]

At 07:14 AM 9/8/00 -0400, Scott Bradner wrote:
> > I don't know what the
> > latency through ethernet switches is, but I'd hope it wasn't in the ms 
> range.
>
>processing time is in the 10 to 50 microsecond range

Don't know whose switches you are evaluating.  They range from sub 1-usec 
to perhaps 5-10 usec - it is all a matter of how much additional processing 
is going on within the switch.  For example, many switches examine not just 
the ethernet headers/tags but also look at the IP headers and provide 
additional functionality based on their content.  This is where many switch 
vendors try to differentiate and is not a function of whether they can 
switch fast or not. The actual switching elements are usually crossbars 
that operate in the 100-500ns range - chip process improvements will lower 
that by quite a bit over the next couple of years.

Mike