Network for Sale

Wed Feb 21 21:18:20 UTC 2001

> >no, that is not the problem.  oh i admit that ping time jitter is ~random.
> >but even if it weren't, RTT doesn't drive performance, (bw*delay)-loss does.
>
> And how does "delay" differ from RTT, except for the obvious constant 
> factor?

my point wasn't that rtt didn't matter but that bandwidth and loss also matter.
so does filesize.  for a 2MB GIF i'd rather have a 900ms * 622Mb/s (satellite?)
link.  for a 2K frame i'd rather have a 60ms * 56K link.  using RTT by itself
as a performance predictor is just silly.  same for aspath length.  the only
way to know if performance will differ between server/proxy A vs B when talking
to client C is to serve from both and see what the tcp window does and what the
total bytes/sec are (if the file is long enough for those to matter.)  the data
then decays rapidly since congestion and routing will change after measurement.