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> From: Srinivasan Keshav <kes...@uwaterloo.ca> > Subject: [e2e] Why do we need congestion control? > Date: March 5, 2013 15:04:48 GMT+01:00 > To: "<end2end-inter...@postel.org>" <end2end-inter...@postel.org> > > To answer this question, I put together some slides for a presentation at the > IRTF ICCRG Workshop in 2007 [1]. In a nutshell, to save costs, we always size > a shared resource (such as a link or a router) smaller than the sum of peak > demands. This can result in transient or persistent overloads, reducing > user-perceived performance. Transient overloads are easily relieved by a > buffer, but persistent overload requires reductions of source loads, which is > the role of congestion control. Lacking congestion control, or worse, with an > inappropriate response to a performance problem (such as by increasing the > load), shared network resources are always overloaded leading to delays, > losses, and eventually collapse, where every packet that is sent is a > retransmission and no source makes progress. A more detailed description can > also be found in chapter 1 of my PhD thesis [2]. > > Incidentally, the distributed optimization approach that Jon mentioned is > described beautifully in [3]. > > hope this helps, > keshav > > [1] Congestion and Congestion Control, Presentation at IRTF ICCRG Workshop, > PFLDnet, 2007, Los Angeles (California), USA, February 2007. > http://blizzard.cs.uwaterloo.ca/keshav/home/Papers/data/07/congestion.pdf > > [2] S. Keshav, Congestion Control in Computer Networks PhD Thesis, published > as UC Berkeley TR-654, September 1991 > http://blizzard.cs.uwaterloo.ca/keshav/home/Papers/data/91/thesis/ch1.pdf > > [3] Palomar, Daniel P., and Mung Chiang. "A tutorial on decomposition methods > for network utility maximization." Selected Areas in Communications, IEEE > Journal on 24.8 (2006): 1439-1451. > http://www.princeton.edu/~chiangm/decomptutorial.pdf > >
