[e2e] Congestion control as a hot topic in IETF
detlef.bosau at web.de
Mon Mar 4 23:48:49 PST 2013
Am 04.03.2013 23:07, schrieb Scharf, Michael (Michael):
> There has been some interesting research on whether a transport protocol could work without any congestion control. One reference is: B. Raghavan and A. Snoeren, "Decongestion Control", ACM SIGCOMM Workshop on Hot Topics in Networks, 2006.
I remember that you, some years ago, asked whether networking can be
done without flow control.
O.k. I just asked my provider to give me some additional space for my
mailbox and claim the following:
Congestion control is necessary, because when God created cabling and
fibre, he forgot to give them a mouth to talk.
So, we actually don't know how much data can reside, if transient, on
the line. And NB: This is anything else but a trivial question.
Particularly on mobile networks, we have only little knowledge about the
transient channel capacity (you might remember some personal discussions
between us two about 8, 9 years ago), if at all. The same holds true for
shared networks e.g. Ethernet, particularly the good old yellow garden hose.
So, actually, the only way to assess whether the amount of data send to
a "media" stays within "acceptable limits" is, simply spoken, trial and
Either it fits - or it is dropped.
Depending on the link technology in use, this situation may vary.
However, the fundamental problem is generic.
While receivers can talk, perhaps God spent more time in creating them,
flow control is easier.
Congestion control is achieved indirectly and - to make things worse -
it is strongly intertwined with scheduling.
Particularly, VJCC attempts to extend TCP's "self clocking" into a "self
scheduling" which is cumbersome because self scheduling requires
sufficient space for the data to be interleaved to be put. I strongly
suspect that the latter is a sufficient reason for what we often call
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