On Nov 2, 2008, at 10:21 PM, William Chops Westfield wrote:

>
> On Nov 2, 2008, at 7:49 PM, Xiaofan Chen wrote:
>
>> So it seems to me that determinism is measured with the
>> jitter (variation of the latency). Is this correct?
>
> I don't think so.  It's like a "hard real time" operating system.
> "Determinism" means that you can guarantee packet delivery within a
> particular maximum time; latency and jitter UP TO that time are free
> to vary all over the place.

This is how I would interpret that also.

Think about something like Token-Ring, if you remember that.  In  
Ethernet, everyone's sharing a bus.  In Token-Ring, you could  
guarantee that "within X number of hundred milliseconds this node in  
this X sized network will get a token, and it will have all of the  
bandwidth between it and the receiving machine to itself until the  
transfer is completed, or X maximum size is reached."

You could mathematically calculate (without trying it on the network)  
the maximum time to transmit any particular sized data from one  
machine to another.  Literally a scratch pad and a pencil and you  
could KNOW if something was taking too long, and go start hunting for  
the problem.

--
Nate Duehr
nate@natetech.com



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