Toke

∆Q is both the concept (quallity attenuation - the fact that delay and 
potential for loss is both conserved and only every increases[1]) and for its 
representation as an improper random variable (one who's CDF doesn't 
necessarily reach one).

One of my adages is that "network quality" doesn' t exist - just like you can't 
buy a box of "dark" and make a room dark by opening the box, you can't buy a 
box of "network quality" - delivering quality in networks is managing (through 
bounding) the "quality attenuation"

Neil
[1] Delay and loss can be traded - i.e resends or even forward error correction 
- but you can't reduce the ∆Q - resends mean increased delay to cover loss, 
forward error correction means increased delay to cover bit error rates) etc 
This is true at any (and all layers) and in *every* queueing and scheduling 
mechanism, just one of those nasty universal properties that we can't get away 
from.

On 27 Apr 2015, at 16:51, Toke Høiland-Jørgensen <[email protected]> wrote:

> Neil Davies <[email protected]> writes:
> 
>> Depends on your starting point:
> 
> Right, having looked a bit more at this:
> 
>> - if it is "how does this relate to the end user" - look at "the
>> properties and mathematics of data transport quality"
> 
> This mentions, on slide 30, an analytical model for predicting (changes
> in) ∆Q. Is this Judy Holyer's "A Queueing Theory Model for Real Data
> Networks", or does it refer to something else?
> 
> -Toke

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