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diff --git a/assignment5.tex b/assignment5.tex new file mode 100644 index 0000000..8289bea --- /dev/null +++ b/assignment5.tex @@ -0,0 +1,108 @@ +\documentclass[a4paper,9pt]{article} + +\author{Camil Staps\\\small{s4498062}} +\title{Networking\\\large{Assignment 5}} +\date{April 27, 2016} + +\usepackage{polyglossia} +\setmainlanguage{english} +\usepackage{geometry} +\usepackage{enumitem} +\setenumerate{label=\alph*)} +\usepackage{amsmath} +\usepackage{minted} + +\begin{document} + +\maketitle + +\section{Packet forwarding} +\begin{enumerate} + \item + \begin{tabular}{l | l} + Dest. addr. & Interface \\\hline + H1 & 1 \\ + H2 & 2 \\ + H3 & 3 \\ + \end{tabular} + + \item No: in a datagram network, the forwarding table entries are tuples of + destination address prefixes and link interfaces. There is no way to + distinguish packets coming from host H1 from packets coming from host H2. + + \item + \begin{tabular}{l | l | l | l} + \multicolumn{2}{c|}{Incoming} & \multicolumn{2}{c}{Outgoing} \\\hline + Interface & VC\# & Interface & VC\# \\\hline + 1 & 13 & 3 & 23 \\ + 2 & 37 & 4 & 47 \\ + \end{tabular} + + \item + \begin{enumerate}[label=\Alph*.] + \setcounter{enumii}{1} + \item + \begin{tabular}{l | l | l | l} + \multicolumn{2}{c|}{Incoming} & \multicolumn{2}{c}{Outgoing} \\\hline + Interface & VC\# & Interface & VC\# \\\hline + 1 & 23 & 2 & 33 \\ + \end{tabular} + + \item + \begin{tabular}{l | l | l | l} + \multicolumn{2}{c|}{Incoming} & \multicolumn{2}{c}{Outgoing} \\\hline + Interface & VC\# & Interface & VC\# \\\hline + 1 & 47 & 2 & 57 \\ + \end{tabular} + + \item + \begin{tabular}{l | l | l | l} + \multicolumn{2}{c|}{Incoming} & \multicolumn{2}{c}{Outgoing} \\\hline + Interface & VC\# & Interface & VC\# \\\hline + 1 & 33 & 3 & 43 \\ + 2 & 57 & 3 & 67 \\ + \end{tabular} + \end{enumerate} +\end{enumerate} + +\section{Switching} +\begin{enumerate}[label=\arabic*.] + \item Only one packet can be handled at the same time, so we may have to wait + for $n-1$ packets. That gives a delay of $(n-1)\cdot D$. + \item Every packet goes to a different output port, so we will never go over + the bus bandwidth (which is at least 1). Therefore, there is no queuing + delay in this case. + \item Every packet goes to a different output port and therefore uses a + different vertical bar in the interconnection network. Queuing can only + occur when two packets need the same vertical line, but as explained this + cannot happen. Therefore, there is no queuing delay in this case either. +\end{enumerate} + +\section{Subnets} +223.1.17.128/26 can support up to 64 addresses (so also 60).\\ +223.1.17.0/25 can support up to 128 addresses (so also 90).\\ +223.1.17.192/26 can support up to 64 addresses (so also 12). + +The subnets do not conflict; their binary prefixes in the last byte are +\texttt{10}, \texttt{0} and \texttt{11} respectively. + +\section{ICMP Traceroute} +\texttt{do\_one\_ping} and the underlying functions have been adapted to return +a tuple \texttt{(address, icmp\_type)} (or \texttt{(None, None)} in case of a +timeout). + +The function \texttt{ping} has been replaced by \texttt{traceroute}. This uses +a counter \texttt{i} to increase the TTL of the echo requests we send. For each +TTL we call \texttt{do\_one\_ping} which gives us either \texttt{(None, None)} +if no server responded, or \texttt{(address, icmp\_type)}, where +\texttt{icmp\_type} is either \texttt{ICMP\_ECHO\_REPLY} or +\texttt{ICMP\_TIME\_EXCEEDED}. We can use this to stop (in case of a reply) or +continue (in case of a TTL excess). + +The logic may be found in \texttt{traceroute}: + +\inputminted[linenos,xleftmargin=1cm,firstline=102,lastline=118]{python}% + {assignment5/traceroute.py} + +\end{document} + |