[e2e] Are Packet Trains / Packet Bursts a Problem in TCP?

Lachlan Andrew lachlan.andrew at gmail.com
Wed Sep 27 19:46:36 PDT 2006

Greetings Fred,

On 26/09/06, Fred Baker <fred at cisco.com> wrote:
> On Sep 26, 2006, at 10:51 AM, Detlef Bosau wrote:
> The big problem in pacing is determining the rate available at the
> bottleneck.

That seems to be confusing rate control with scheduling.

A pacing scheme can measure the RTT and still maintain a "window"
(even though not used as a sliding window), following the standard
rules of (New)Reno/SACK/H-TCP/...

If we pace packets out at a rate "window / RTT" then we transmit at
the same average rate as if we used ACK-clocking.  The only difference
is that the packets are sent with roughly equal spacing in the case of
pacing, and sent irregularly with pure ACK-clocking.

Am I missing something?


Lachlan Andrew  Dept of Computer Science, Caltech
1200 E California Blvd, Mail Code 256-80, Pasadena CA 91125, USA
Phone: +1 (626) 395-8820    Fax: +1 (626) 568-3603

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