On 28 May 2014, at 18:29, David Collier-Brown <[email protected]> wrote:
> On 05/28/2014 11:33 AM, Jonathan Morton <[email protected]> wrote >> It's a mathematical truth for any topology that you can reduce to a black >> box with one or more inputs and one output, which you call a "queue" and >> which *does > not discard* packets. Non-discarding queues don't exist in the real > world, of course. >> >> The intuitive proof is that every time you promote a packet to be >> transmitted earlier, you must demote one to be transmitted later. A >> non-FIFO queue tends to increase the maximum delay and decrease the minimum >> delay, but the average delay will remain constant. > > A niggle: people working in queuing theory* make the simplifying > assumption that queues don't drop. When describing the real world, they > talk of "defections", the scenario where a human arrives at the tail of > the queue and "defects", either to another queue or to the exit door of > the store! There is another mathematical approach that we've found very useful, actually the original work goes back to the 1950's (M/M/1/K/K). As mentioned in a reply just now in a different thread, it does give some interesting insights into the underlying two-degrees of freedom that are present in every finite queue. > As you might guess, what I find intuitive the IP world finds wrong, and > vice versa. > > --dave > [* as opposed, perhaps, to queuing networks (:-)] > -- > David Collier-Brown, | Always do right. This will gratify > System Programmer and Author | some people and astonish the rest > [email protected] | -- Mark Twain > > > > -- > David Collier-Brown, | Always do right. This will gratify > System Programmer and Author | some people and astonish the rest > [email protected] | -- Mark Twain > _______________________________________________ > Bloat mailing list > [email protected] > https://lists.bufferbloat.net/listinfo/bloat _______________________________________________ Bloat mailing list [email protected] https://lists.bufferbloat.net/listinfo/bloat
