\section{Congestion Control Issues}

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\begin{slide}{}

   \begin{sitem}
      \item Two sides of the same coin
      \begin{sitem}
         \item pre-allocate resources so at to avoid congestion
         \item send data and control congestion if (and when) is occurs
      \end{sitem}
            
      \pichere{/congestion.eps,height=2in}

      \item Two points of implementation
      \begin{sitem}
         \item hosts at the edges of the network (transport protocol)
         \item routers inside the network (queuing discipline)
      \end{sitem}

      \item Underlying service model
      \begin{sitem}
         \item best-effort (assume for now)
         \item multiple {\it qualities of service} (later)
      \end{sitem}        
   \end{sitem}        
\end{slide}
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\begin{slide}{}

   \begin{sitem}
      \item Connectionless flows
      \begin{sitem}
         \item sequence of packets sent between source/destination pair
         \item maintain {\it soft state} at the routers
      \end{sitem}        

      \pichere{flow.eps,height=2in}       

      \item Taxonomy
      \begin{sitem}
         \item router-centric versus host-centric
         \item reservation-based versus Feedback-based
         \item window-based versus rate-based
      \end{sitem}

      \item Evaluation
      \begin{sitem}
         \item fairness
         \item power (ratio of throughput to delay)
      \end{sitem}
      \pichere{power.eps,height=1.5in}

   \end{sitem}
\end{slide}




