[e2e] Are we doing sliding window in the Internet?
detlef.bosau at web.de
Wed Jan 3 03:13:10 PST 2007
Lachlan Andrew wrote:
> On 02/01/07, Joe Touch <touch at isi.edu> wrote:
>> Detlef Bosau wrote:
>> > Round CWND
>> > 1 2
>> > 2 4
>> > 3 8
>> It doesn't double each RTT; it goes up by 50%. Remember, the window
>> grows by one MSS each ACK during the initial phase, but there is one ACK
>> for each two MSS's.
> If you have ABC (as recent Linux senders do by default), or don't use
> delayed ACKs (as Linux receivers don't when the window is small),
> Detlef was right that it doubles each RTT.
Just before I´m to end my life on "Yellow Mama" ....... ;-)
I admit that I often forget to mention all my assumptions. And even
more, I don´t have all the RFCs in mind, particularly not rfc 3390,
which Joe has in mind when he talks of an initial window of 4 MSS.
When I do NS2 simulations, I mostly turn off delayed ACKs for my
purposes at the moment.
From the congavoid paper, I understand that the intention was to double
CWND each round if the sender is in slow start state and to increase it
by 1 MSS each round when the sender is in congestion avoidance state.
From my understanding it is not necessary for the AIMD scheme to work
that this doubling/increasing happens every or every other round.
Of course, it affects the convergence time.
I´m talking too much. Please forgive me, if I miss to mention all my
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