[e2e] Why do we need TCP flow control (rwnd)?

Lachlan Andrew lachlan.andrew at gmail.com
Thu Jun 26 10:29:11 PDT 2008

On 26/06/2008, David P. Reed <dpreed at reed.com> wrote:
>  So the rwnd parameter is NOT actually measuring buffer pool size.   It is
> actually a control loop that measures the endpoint application's ability to
> do work.

That is a good point.  However, most systems still  do  set   rwnd
based on the buffer pool size (as, I believe, the RFCs still require).

There has been work on using  rwnd  for congestion control instead of
to signal the buffer pool size.  Mukhtar, Hanly and I did some
<http://netlab.caltech.edu/lachlan/abstract/CLAMP-TMC07.pdf>, but were
by no means the first.

There has also been work on senders selectively ignoring  rwnd  when
the buffer pool is small compared to the BDP, but the receiver is
still keeping pace with the sending rate.  Sorry, I don't have refs
for that.


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

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