From: pimjager Date: Wed, 11 Nov 2015 14:14:54 +0000 (+0100) Subject: Add explenation of partitions X-Git-Url: https://git.martlubbers.net/?a=commitdiff_plain;h=e0f0fe4cb2710b507fdcf6193ae61a9c32e2d539;p=tt2015.git Add explenation of partitions --- diff --git a/a2/1cases.tex b/a2/1cases.tex index 1bfdc39..9ffc07d 100644 --- a/a2/1cases.tex +++ b/a2/1cases.tex @@ -89,13 +89,14 @@ a feasible test suite the tests are divided into equivalence partitions. Below these partitions are given. \begin{enumerate} - \item \emph{Number of packets} in request~\footnote{A request is considered - establishing a connection (handshake) and a number of payload packets} + \item \emph{Number of segments} in request~\footnote{A request is + considered establishing a connection (handshake) and a number of + payload segments} \begin{enumerate} - \item 0 payload packets - \item 1 payload packet - \item n=small payload packets - \item n=big payload packets + \item 0 payload segments + \item 1 payload segments + \item n=small payload segments + \item n=big payload segments \end{enumerate} \item \emph{source port} \begin{enumerate} @@ -107,11 +108,11 @@ these partitions are given. \item Correct \item Incorrect \end{enumerate} - \item Bits flipped in \emph{payload} + \item Bit errors in \emph{payload} \begin{enumerate} \item Correct payload - \item Payload with bit flips - \item Payload with odd number of bits flipped + \item Payload with bit flips that do not show in checksum + \item Payload with bit flips that do show in checksum \end{enumerate} \item \emph{checksum} \begin{enumerate} @@ -129,24 +130,29 @@ these partitions are given. These partitions were chosen since they correspond to key parts of the TCP specification. -TCP segments are send over a TCP connection from a \emph{source} to a \emph{destination port}. Therefore segments which are received which have a +TCP segments are send over a TCP connection from a \emph{source} to a \emph{destination port}. Therefore segments which are received that have a source or destination port set to an incorrect value should not be regarded -as segments belonging to the connection. +as segments belonging to the connection by the SUT. TCP uses a \emph{checksum} to catch any error introduced in headers, when this -checksum does not match the actual computed checksum the packet should be -disregarded. +checksum does not match the actual computed checksum the SUT should +disregard the received segment. The TCP checksum is also an inherently weak one, as it is simply the -bitwise negation of the addition in ones complement arithmetic +bitwise negation of the addition, in ones complement arithmetic, of all 16 bit words in the header and data of the segment (excluding the -header). Therefore any bit error where the ones complement value of one word +checksum itself). Therefore any \emph{bit error} where the ones complement value +of one word increases by one, and the value of another decreases by one, is undetected. The SUT should exhibit the same behavior and accept packets where these type -of bit error occur. +of bit errors occur. + +TCP guarantees that segments are delivered in order,even when they are received +\emph{out of order} and that missing segments are resend. The SUT should +exhibit the same behavior. If segments are received out of order it should +deliver them in order. Missing segments should be re-requested (by ACK-ing +the correct sequence number). -\textbf{hier iets over waarom deze partities relevant zijn! Waarom odd en -even number of bits flipped bijv interessant?} \bigskip Partitions 2 to 6 are tested using pairwise testing to keep the number of test