[SPAM] Re: SCP speed question

[Alma J Wetzker]

Bill Campbell wrote:
> On Wed, Jan 10, 2007, Alma J Wetzker wrote:
>> Rick Bowers wrote:
>>> At 1/6/2007 12:08 AM, you wrote:
>>>> Are you sure you're not seeing between 4 and 11MB/s?  Most measurements of
>>>> transfer speed are done in BYTES not bits, as the network gear is rated.
>>>> Approx divide by 10, particularly over wan links (analog: 8 bits data, 1
>>>> start, 1 stop).  Or if you want to think perfect world switching, /8 is more
>>>> your cup o' tea.
>>> Perhaps I'm wrong, but I thought start/stop bits applied only to 
>>> synch/asynch communications. TCP/IP has no start/stop bits as far as 
>>> I know. So, don't we (mostly) all divide by 8 these days?
>> The only time I am aware of that you can divide by eight is on a pure
>> synchronous connection with out of band signaling.  That ain't Ethernet.
>> At a physical level, you need some mechanism to make sure the send and
>> receive clocks are the same speed, at the very least.  That overhead
>> will occur well below the TCP layers.  It still is a divide by ten rule.
>> The exception is ISDN (and some types of DSL) that are pure synchronous.
> 
> This whole argument is about as silly as NFL referees measuring
> things to inches that are accurate to a yard or so at best.  It's
> like trying to get 10 significant digits of accuracy when using a
> slide rule for the calculations.
> 
> Whether one divides by 8 or 10 here doesn't make a whole lot of
> difference when one is doing rough performance checks, and really
> are relevant only in evaluating whether a change makes it better
> or worse.  It's the relative changes that are meaningful.

So, are you saying that we need to drop the thread?  This is something
that I actually know something about. ;)

    -- Alma