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

Joe Touch touch at ISI.EDU
Wed Jan 3 14:46:15 PST 2007



Lachlan Andrew wrote:
> Greetings,
> 
> 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.

If you believe that's true, please present some verification. An
implementation based on an assertion is insufficient.

> (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).  

Agreed.

> To me, that *is* a good reason to
> override a SHOULD.

Thought experiments are *lousy* reasons to override SHOULDs. The desire
for something better than what we currently have is an equally lousy
reason by itself. If you have evidence, please make the case and get the
community to agree and deploy this everywhere.

Joe

-- 
----------------------------------------
Joe Touch
Sr. Network Engineer, USAF TSAT Space Segment

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