Subject: Re: tcp initial window and rate pacing...

From: Venkat Padmanabhan <[email-masked]>
Date: Tue, 27 Oct 1998 11:32:20 -0800

> But has anyone considered, in addition to larger windows, also
> pacing the generation of the initial burst of packets at a relatively
> low rate so that one can an even slightly larger initial window
> yet avoiding overflows at the network edges (e.g.  dialup users) ?

I considered this in TCP fast start, which I developed as part of my
thesis (http://www.cs.berkeley.edu/~padmanab/phd-thesis.html).
This also appears in the 1998 Global Internet Conference
(http://www.cs.berkeley.edu/~padmanab/papers/gi98.ps).

I made no assumptions about how often information from the past
would be valid. Therefore, I had two goals: 

1. To reduce latency by reusing window information when such information
is valid.
2. To avoid performance degradation when the information is stale.

I used priority dropping to shield other traffic in case the cached window
is stale (and too large), and some special techniques to quickly detect
and abort a failed fast start attempt. My experimental results showed that 
not doing so could cause much worse performance than with standard 
slow start in certain situations, clearly an undesirable outcome.

-Venkat

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From: Vern Paxson <[email-masked]>
Date: Tue, 27 Oct 1998 12:58:46 PST

Let's please migrate this thread to end2end-interest - thanks.

		Vern