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| -rw-r--r-- | assignment3.tex | 26 |
1 files changed, 16 insertions, 10 deletions
diff --git a/assignment3.tex b/assignment3.tex index b779e7e..c50e5c2 100644 --- a/assignment3.tex +++ b/assignment3.tex @@ -47,33 +47,33 @@ \section{Design a protocol} See \autoref{fig:3-fsm}. -\section{Analyse protocols} -\def\trans#1#2{\footnotesize{\texttt{\uline{#1\hfill\mbox{}}\\#2}}} +\def\trans#1#2{\footnotesize{\texttt{\uline{#1\hfill\mbox{}}\\[2pt]#2}}} \tikzstyle{trans}=[every trans] \begin{figure}[h] + \def\nl{\\[-3pt]} \centering \begin{subfigure}{\textwidth} \centering \begin{tikzpicture}[node distance=35mm,->,>=stealth',every trans/.style={text width=4cm},every state/.style={ellipse}] \node[initial,state] (a1) {Wait/Send}; - \node[state,right of=a1] (a2) {Retry/Wait}; + \node[state,right of=a1] (a2) {Wait/Receive}; - \path (a1) edge[bend left] node[trans,above] {\trans{rdt\_send(data)}{packet=make\_pkt(data)\\udt\_send(packet)}} (a2) - (a2) edge[loop right,looseness=4.5] node[trans,right] {\trans{rdt\_unable\_to\_send(data)}{packet=make\_pkt(data)\\udt\_send(data)}} (a2) - edge[bend left] node[trans,below] {\trans{rdt\_rcv(packet)}{extract(packet,data)\\deliver\_data(data)}} (a1); + \path (a1) edge[bend left] node[trans,above] {\trans{rdt\_send(data)}{packet=make\_pkt(data)\nl udt\_send(packet)}} (a2) + (a2) edge[loop right,looseness=4.5] node[trans,right] {\trans{rdt\_send(data)}{rdt\_unable\_to\_send(data)}} (a2) + edge[bend left] node[trans,below] {\trans{rdt\_rcv(packet)}{extract(packet,data)\nl deliver\_data(data)}} (a1); \end{tikzpicture} \caption{Entity A} \end{subfigure} \begin{subfigure}{\textwidth} \centering \begin{tikzpicture}[node distance=35mm,->,>=stealth',every trans/.style={text width=4cm},every state/.style={ellipse}] - \node[state] (b1) {Retry/Wait}; + \node[state] (b1) {Wait/Receive}; \node[state,right of=b1] (b2) {Wait/Send}; \draw[<-] (b1) -- ++(-7mm,7mm) node[above left] {start}; - \path (b2) edge[bend left] node[trans,below] {\trans{rdt\_send(data)}{packet=make\_pkt(data)\\udt\_send(packet)}} (b1) - (b1) edge[loop left,looseness=4.5] node[trans,left] {\trans{rdt\_unable\_to\_send(data)}{packet=make\_pkt(data)\\udt\_send(data)}} (b1) - edge[bend left] node[trans,above] {\trans{rdt\_rcv(packet)}{extract(packet,data)\\deliver\_data(data)}} (b2); + \path (b2) edge[bend left] node[trans,below] {\trans{rdt\_send(data)}{packet=make\_pkt(data)\nl udt\_send(packet)}} (b1) + (b1) edge[loop left,looseness=4.5] node[trans,left] {\trans{rdt\_send(data)}{rdt\_unable\_to\_send(data)}} (b1) + edge[bend left] node[trans,above] {\trans{rdt\_rcv(packet)}{extract(packet,data)\nl deliver\_data(data)}} (b2); \end{tikzpicture} \caption{Entity B} \end{subfigure} @@ -81,5 +81,11 @@ See \autoref{fig:3-fsm}. \label{fig:3-fsm} \end{figure} +\section{Analyse protocols} +\begin{description} + \item[GBN] As long as we cannot send two packets with the same sequence number at the same time, we're fine. A GBN receiver discards all packets but the packet it expects. Therefore, the largest allowable sender window is $k$. + \item[SR] It should not be the case that the receiver \emph{expects} a packet with sequence number $N$ \emph{and} finds another packet with sequence number $N$ \emph{acceptable}. Therefore, the largest allowable sender window (which equals the largest allowable receiver window) is $k$ for this protocol as well. +\end{description} + \end{document} |