[RE] Comparing graphical analysis and analytical
I've looked through the David's charts
and figures in the effort to synchronize our results on the worst-case
latency figures. Few observations:
1) Graphical analysis is considering
both input-queue and output-queue routers. My work exclusively deals with
the output-queue routers.
2) In graphical analysis of traffic
patterns I couldn't find an explicit value for bandwidth shaping period
under consideration. This definitely has an effect on the outcome. For
the 3 port output queue analysis it seemed that 125 mks shaping period
was used.
3) For the output-port router graphical
analysis for 3 ports, figures are actually in a very good agreement with
the analytical formula for the shaping period of 125 mks and 75% link utilization.
In fact when I graphed latency values from the David's paper they where
almost linear and also fit tightly with the graphs produced analytically.
On the attached graph, analytical curve is black, while curve from the
values in the Dave's paper (http://grouper.ieee.org/groups/802/3/re_study/public/200509/dvjBurstAndBunch2005Sep26.pdf,
table F.3 on the page 10) is blue.
All this leads me to believe that there
no drastic disagreement in results at all!
Max.graphAnalyticalComp.gif
