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<div class="moz-cite-prefix">Am 06.03.2013 13:29, schrieb shun cai:<br>
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cite="mid:CANZhn5Gqyw6-XpaB2-XKmbahKidOap+ZDqGAJ2NqdMBxmYAP-w@mail.gmail.com"
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As discussed in chapter 1 of your PhD thesis, when network is
congested, retransmission dominate the traffic and effective
throughput diminshes rapidly, leading to a deteriorating
situation. This can be illustrated in the well known figure with
two turning points Knee and Cliff. <br>
<img moz-do-not-send="true" alt=""><br>
<br>
I wonder, however, does the situation the same if rateless
erasure code (say fountain codes) is used? As with erasure code,
no ACK and retransmission is needed except when the whole file is
completed. So even heavy loaded, the network is still busy with
effective data packet, right? Although queueing delay will
increase, I believe that the network throughput will not suffer
the plunge as un-coded network. <br>
<br>
<br>
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<br>
Very short answer, because I'm not quite familiar with erasure
codes. <br>
<br>
However, we're moving around overhead here. In the end, it doesn't
matter whether your network suffers from retransmission overload and
the goodput as seen by the user runs to zero or of the network
suffers from "unsatisfactory code rates" where 1 packet is encoded
into
10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
packets so that it can be recovered.<br>
<br>
To the point: Flow control and congestion control are supposed to <i>solve</i>
a problem, not to <i>worsen</i> it. <br>
<br>
And from what I read in some off list discussions which developed
from this thread here, there are quite some people who claim that
VJCC is quite a kludge. At the moment, I have no clear position to
that claim, though in some of the PMs I got, I missed the necessary
respect towards Van's work. And quite some mails argued more
historically than scientifically which I personally find annoying.<br>
<br>
Sliding window & Co. were invented to fully utilize network
capacities. You cannot over utilize them. Or, wrt the 12 basic
network truths: No matter how you push or pull, no matter what
priority your project may have: You cannot increase the speed of
light.<br>
<br>
<pre class="moz-signature" cols="72">--
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