http://www.cs.washington.edu/research/networking/detour/local/triangle/index.html
On Tue, 6 Oct 1998, Stefan Savage wrote:
> Date: Tue, 6 Oct 1998 12:19:12 -0700
> From: Stefan Savage <savage@cs.washington.edu>
> To: John M Snell <geigudr@cs.washington.edu>,
syn@cs.washington.edu
> Subject: RE: best analysis metric, next measurement phase?
>
> As a first cut, can we see what the drop rate looks like using the best
> latency data and vice versa?
>
> >From the standpoint of TCP performance, a metric would be to weight RTT
> linearly and packet drops as 1/sqrt(p) (ie chose a shorter path over an
> equally smaller packet drop rate). In truth though, this is a flawed
> metric without a model of the resource usage on the link. Both the
> latency and the drop rate are dependent on the amount of flow pushed
> down the path. We don't know what that function is. My intuition is
> that the optimal tradeoff between RTT and p will change over their
> range. My GUESS is that for low values of p, reductions in RTT will
> matter much more, and for high values of p reductions in p will count
> more. I expect this effect will be much stronger for short flows than
> long.
>
> However, as Neal wrote, I suggest using the the linear p, inverse
> quadratic p metric for now... and lets see what the graph looks like.
>
> - Stefan
>
>
> -----Original Message-----
> From: John Snell [mailto:geigudr@cs.washington.edu]
> Sent: Tuesday, October 06, 1998 10:41 AM
> To: syn@cs.washington.edu
> Subject: best analysis metric, next measurement phase?
>
>
>
> Question:
>
> The next phase of the measurement study has me generating a runtime
> graph
> of the network, whose edges are weighted acording to some measured
> property -- ie, latency, loss, hops, etc.
>
> Previously I'd thought to separately use both latency and loss (ie, do
> multiple alternate path measurements for the same path). This is
> proving
> to be too expensive, pushing me towards using one single metric.
>
> Tom had recommended using the Savage/Cardwell power metric. Anyone else
> have suggestions on a good metric?
>
> -John
>
>
> ---------- Forwarded message ----------
> Date: Mon, 5 Oct 1998 15:51:18 -0700 (PDT)
> From: Tom Anderson <tom@emigrant>
> To: geigudr@cs.washington.edu
> Subject: Re: one other thing...
>
> i got hammered at MIT for the fact that the latency graph
> is optimized for latency, and the drop rate graph is optimized
> for drops, but there is no guarantee you can get both.
>
> I'd rather get group feedback on this one. Can you pose it as
> a design question to the group?
>
> tom
>