[e2e] Are we doing sliding window in the Internet?

Lachlan Andrew lachlan.andrew at gmail.com
Wed Jan 3 14:37:46 PST 2007


On 03/01/07, Joe Touch <touch at isi.edu> wrote:
> I.e., "delayed ACK" *means* sending fewer than one ACK per received
> segment.

It obviously doesn't mean that *every* packet should be ACK'd less
than once (i.e., zero times).  It means that *some* packets should not
be ACK'd, just as Linux does once the transmission is underway.

> I don't see sufficient
> reason in "well, it makes *us* go faster" to warrant overriding SHOULD.

Agreed!!  Selfishness should be discouraged.

The point is that if *everyone* used QuickACKs, short transfers would
be faster, with almost no harm done to long flows.  (It is a better
approximation to "shortest job first", which is well known to minimise
the average delay for a given utilisation.)  It is well known that
slow start is too slow for modern bandwidth-delay products (althought
it was fine when it was proposed).  To me, that *is* a good reason to
override a SHOULD.


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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