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[ih] Where is VJCC? Re: O.k., so BSD 4.3 Tahoe is the version of interest.

GBN is indeed a term of art and was used in link protocols that maintained
packet boundaries and retransmitted them in that form. TCP was different
because it was delivering a bytestream. louie is correct in his
characterization. Whether all unacked data was resent was partly
idiosyncratic to the implementation of TCP and partly a function of the
current window size. As i recall, it was recommended not to reduce the
window to less than previously permitted transfers.


On Wed, May 28, 2014 at 8:32 AM, Louis Mamakos <louie at transsys.com> wrote:

> While I was a little late to the party (our TCP didn?t start to get
> written until early 1981), I don?t recall any discussion of GBN at the
> time.  Perhaps that was a term of art invented later to describe all this.
>  The retransmission mechanism was to send unacknowledged data from the
> "left window edge? of the TCP ?send window?.  By definition, that?s where
> all of the unacknowledged data in the sliding window existed.
> The decision of how much data to send was implementation specific.  I
> can?t imagine sending less than a whole TCP MSS on a retransmission
> attempt.
> louie
> On May 28, 2014, at 6:55 AM, Vint Cerf <vint at google.com> wrote:
> GBN is a funny way to characterize the process - the retransmission has to
> be limited by window permissions at least.
> v
> On Wed, May 28, 2014 at 6:34 AM, Detlef Bosau <detlef.bosau at web.de> wrote:
>> My joy was a bit to early, this version doesn't contain the VJCC actions
>> but uses cwnd for source quench. (To my understanding, from the
>> congavoid paper, VJ introduced a state variable cwnd, obviously it is
>> already present here?) However, I don't find the actions
>> "window halving" on time out and for the window increase, I find a
>> probing in case of missing source quenchs.
>> Anyway, as far as I see at the moment, this code clearly does Go Back N
>> in case of an expiring retransmission timer and timer backoff.
>> --
>> ------------------------------------------------------------------
>> Detlef Bosau
>> Galileistra?e 30
>> 70565 Stuttgart                            Tel.:   +49 711 5208031
>>                                            mobile: +49 172 6819937
>>                                            skype:     detlef.bosau
>>                                            ICQ:          566129673
>> detlef.bosau at web.de                     http://www.detlef-bosau.de
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