From: Janet Davis (jlnd_at_cs.washington.edu)
Date: Sun Feb 08 2004 - 17:52:10 PST
On Sun, 8 Feb 2004, minhtri h le wrote:
> Correct me if I'm wrong, but we notice that on problem 2, there were two
> packets that were lost (never ACKed by "them")
> those being...
>
> me > them p 2897:4345
> and
> me > them p 5793:7241
It's good that you noticed this.
In TCP, acknowledgements are cumulative. The acknowledged byte is
actually the next byte expected (you can read more about this in Peterson
5.2.4). This means that when them sends an acknowledgement saying it is
expecting byte 5793, it has received everything before that byte,
including 2897:4345.
These packets weren't lost--if that were the case, they would have been
retransmitted. The acknowledgment might have gotten lost, or the data
packets may have arrived out of order, or the receiver may have waited to
receive more data before sending an acknowledgement (this is called
"delayed acknowledgement").
Cheers,
Janet
-- Janet Davis jlnd_at_cs.washington.edu http://www.cs.washington.edu/homes/jlnd/ _______________________________________________ Cse461 mailing list Cse461_at_cs.washington.edu http://mailman.cs.washington.edu/mailman/listinfo/cse461
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