[e2e] Stupid Question: Why are missing ACKs not considered as indicator for congestion?

Joe Touch touch at ISI.EDU
Thu Feb 1 06:05:43 PST 2007



Lloyd Wood wrote:
> At Wednesday 31/01/2007 16:02 -0500, Sushant Rewaskar wrote:
>> Hi,
>> I agree with Lachlan. In TCP there is no way to know when an ack is lost as
>> it carries no "sequence number" of its own. 
> 
> It can - timestamps are used for disambiguation, and they
> disambiguate the acks. They can act as unique sequence numbers.

How so? RFC 1323, Sec 4.2.2:

"Based upon these considerations, we choose a timestamp clock
         frequency in the range 1 ms to 1 sec per tick.  "

That suggests that timestamps need not be unique by themselves.

Joe

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

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