[e2e] A simple scenario. (Basically the reason for the sliding window thread ; -))

Detlef Bosau detlef.bosau at web.de
Thu Jan 11 02:07:25 PST 2007

Ted Faber wrote:
> On Thu, Jan 11, 2007 at 12:25:24AM +0000, Lloyd Wood wrote:
>> At Thursday 11/01/2007 00:29 +0100, you wrote:
>>> Well, it´s just how I understand the semantics of a "CLOSE ACK". When a receiver issues a CLOSE ACK,
>> ...the ACK starts off CLOSE to the receiver and then goes FURTHER
>> AWAY, ending up a FAR ACK. That's the semantics.
> And if you collect 5 of them, it's a FIN ACK.  Which may be where we
> were *trying* to go. :-)

I apologize if this is a stupid question, but from the RFC I understood 
that the receiving socket sends an acknowledgement when all data was 
received. That´s CLOSE ACK.

Is there an explicit acknowledgement which tell´s the sender that all 
data has been delivered to the _application_? Can this even be achieved 
in finite time? An application may crash or hang!

To my understanding the Fin/FinACK/..... is to shut down a TCP 
connection knowing about the two army problem and the fact that this 
cannot be solved in finite time?

I apologizse when this is a misconception...


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