Re: [Bloat] Detecting bufferbloat from outside a node

[Neil Davies <neil.davies@pnsol.com>]

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 <toke@toke.dk> wrote:

> Neil Davies <neil.davies@pnsol.com> 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