[e2e] How many TCP flows fit in the Internet?

Detlef Bosau detlef.bosau at web.de
Sun Mar 31 11:18:45 PDT 2013


Am 31.03.2013 20:08, schrieb Matt Mathis:
> You may have overlooked one additional important detail:
>
> Linux TCP ignores the requirement in RFC 2018 that the SACK scoreboard

Admittedly, I did not have SACK in mind.
> be cleared on a timeout.  As a consequence, Linux TCP can attain total
> goodput=throughput for a single forward path bottleneck with average
> window size way below one segment.

However, I usually look into the RFC and don't take Linux as a standard.

Nevertheless, you exactly got my point.
>     This is because it will not
> retransmit segments that are delivered.

Hence, the average number of data in flight may be less than one 
segment, which can be achieved by TCP pacing as well, however I'm still 
to understand the paper on pacing by Aggarval, Savage and Anderson, 
because they point to some deficiencies of pacing, so there may be some 
issues.

> This region has important
> theoretical interest (it evades congestion collapse!) but is
> irrelevant from an operational perspective (nobody want to use a
> network that is so congested that the average available capacity is
> measured in bits per second.)

Extremely interesting.

Many thanks!

Detlef

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