\documentclass[10pt,a4paper]{article}

% Packages
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%\usepackage{opensans}          % Can't make this work so far. Shame. Would be lovely.
\usepackage[normalem]{ulem}     % For underlining links
% Most of the following are not required for the majority
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\usepackage{amsmath}            % Symbols
\usepackage{MnSymbol}           % Symbols
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%\usepackage[english,german,french,spanish,italian]{babel}              % Languages

% Document Info
\author{shashi}
\pdfinfo{
  /Title (physical-and-data-link-layer.pdf)
  /Creator (Cheatography)
  /Author (shashi)
  /Subject (Physical and Data Link Layer Cheat Sheet)
}

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\newcommand{\SetRowColor}[1]{\noalign{\gdef\RowColorName{#1}}\rowcolor{\RowColorName}} % Shortcut for row colour
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% Header and Footer
\pagestyle{fancy}
\fancyhead{} % Set header to blank
\fancyfoot{} % Set footer to blank
\fancyhead[L]{
\noindent
\begin{multicols}{3}
\begin{tabulary}{5.8cm}{C}
    \SetRowColor{DarkBackground}
    \vspace{-7pt}
    {\parbox{\dimexpr\textwidth-2\fboxsep\relax}{\noindent
        \hspace*{-6pt}\includegraphics[width=5.8cm]{/web/www.cheatography.com/public/images/cheatography_logo.pdf}}
    }
\end{tabulary}
\columnbreak
\begin{tabulary}{11cm}{L}
    \vspace{-2pt}\large{\bf{\textcolor{DarkBackground}{\textrm{Physical and Data Link Layer Cheat Sheet}}}} \\
    \normalsize{by \textcolor{DarkBackground}{shashi} via \textcolor{DarkBackground}{\uline{cheatography.com/213612/cs/46527/}}}
\end{tabulary}
\end{multicols}}

\fancyfoot[L]{ \footnotesize
\noindent
\begin{multicols}{3}
\begin{tabulary}{5.8cm}{LL}
  \SetRowColor{FootBackground}
  \mymulticolumn{2}{p{5.377cm}}{\bf\textcolor{white}{Cheatographer}}  \\
  \vspace{-2pt}shashi \\
  \uline{cheatography.com/shashi} \\
  \end{tabulary}
\vfill
\columnbreak
\begin{tabulary}{5.8cm}{L}
  \SetRowColor{FootBackground}
  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Cheat Sheet}}  \\
   \vspace{-2pt}Not Yet Published.\\
   Updated 3rd June, 2025.\\
   Page {\thepage} of \pageref{LastPage}.
\end{tabulary}
\vfill
\columnbreak
\begin{tabulary}{5.8cm}{L}
  \SetRowColor{FootBackground}
  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Sponsor}}  \\
  \SetRowColor{white}
  \vspace{-5pt}
  %\includegraphics[width=48px,height=48px]{dave.jpeg}
  Measure your website readability!\\
  www.readability-score.com
\end{tabulary}
\end{multicols}}




\begin{document}
\raggedright
\raggedcolumns

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% from this page to resize cheat sheet text:
% www.emerson.emory.edu/services/latex/latex_169.html
\footnotesize % Small font.

\begin{multicols*}{3}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Transmission Media}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Transmission media is a communication channel that transmits information from the source/transmitter to the receiver} \tn 
% Row Count 3 (+ 3)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Wired Media}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{{\bf{Type}}} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{{\bf{Twisted Pair}}} \tn 
% Row Count 2 (+ 1)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{{\bf{Coaxial Cable}}} \tn 
% Row Count 3 (+ 1)
% Row 3
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{{\bf{Fiber Optic}}} \tn 
% Row Count 4 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{1.29487 cm} p{0.79363 cm} p{0.75186 cm} x{1.33664 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{4}{x{5.377cm}}{\bf\textcolor{white}{Wireless Media}}  \tn
% Row 0
\SetRowColor{LightBackground}
{\bf{Type}} & {\bf{Range}} & {\bf{Speed}} & {\bf{Use Cases}} \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
Radio Waves & Short to Medium & Medium & WLANs, mobile phones \tn 
% Row Count 5 (+ 3)
% Row 2
\SetRowColor{LightBackground}
Microwaves \seqsplit{Unidirectional} & Long & High & Satellite links, cellular \tn 
% Row Count 8 (+ 3)
% Row 3
\SetRowColor{white}
Infrared (IR) & Very short & Low & Remote controls \tn 
% Row Count 10 (+ 2)
% Row 4
\SetRowColor{LightBackground}
Satellite & Global & Medium to High & Global \seqsplit{communication} \tn 
% Row Count 12 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}----}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{2.4885 cm} x{2.4885 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Types of Parity}}  \tn
% Row 0
\SetRowColor{LightBackground}
Even Parity & Odd Parity \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
Total number of 1s (including parity bit) must be even. & Total number of 1s (including parity bit) must be odd. \tn 
% Row Count 4 (+ 3)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{{\bf{Limitation:}} Detects only odd number of bit errors (fails if two bits flip).}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{1.54287 cm} x{3.43413 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Real-World Applications}}  \tn
% Row 0
\SetRowColor{LightBackground}
PARITY & Used in RAM error detection. \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
{\bf{Checksum}} & TCP/IP headers, UDP. \tn 
% Row Count 3 (+ 1)
% Row 2
\SetRowColor{LightBackground}
{\bf{CRC}} & Wi-Fi, ZIP files \tn 
% Row Count 4 (+ 1)
% Row 3
\SetRowColor{white}
{\bf{Hamming Code}} & ECC memory, satellite communication. \tn 
% Row Count 6 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Introduction to MAC Protocols}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{{\bf{MAC (Media Access Control) protocols determine how devices share a communication channel to avoid collisions.}}} \tn 
% Row Count 3 (+ 3)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{{\bf{Used in:}} Ethernet (wired) and Wi-Fi (wireless).} \tn 
% Row Count 5 (+ 2)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{{\bf{Goal:}} Ensure fair and efficient transmission.} \tn 
% Row Count 6 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{CSMA/CD}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{CSMA/CA, is a channel access method used in wireless networks, particularly in IEEE 802.11 (Wi-Fi), to manage access to the shared communication channel and prevent collisions.} \tn 
% Row Count 4 (+ 4)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{How CSMA/CA Works} \tn 
% Row Count 5 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{1.	Carrier Sense (CS): \newline        {\emph{ Device checks if the channel is idle.}} \newline 2.	Collision Avoidance (CA): \newline        {\emph{Uses RTS/CTS (Request to Send / Clear to Send) to reserve the channel.}} \newline         {\emph{Waits for DIFS (DCF Interframe Space) before transmitting.}} \newline 3.	Random Backoff Timer: \newline         {\emph{ If busy, waits for a random time (contention window) before retrying.}}}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Framing}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Framing is the process of dividing a continuous stream of data into manageable chunks called frames for transmission.} \tn 
% Row Count 3 (+ 3)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{1.84149 cm} x{3.13551 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Framing Techniques}}  \tn
% Row 0
\SetRowColor{LightBackground}
{\bf{Technique}} & {\bf{Description}} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
{\bf{Character Count}} & Frame starts with a count of the number of characters in the frame. \tn 
% Row Count 4 (+ 3)
% Row 2
\SetRowColor{LightBackground}
{\bf{Byte Stuffing}} & Special characters added to distinguish data from control info (e.g., FLAG -\textgreater{} ESC FLAG). \tn 
% Row Count 8 (+ 4)
% Row 3
\SetRowColor{white}
{\bf{Bit Stuffing}} & Inserts 0 after a sequence of 5 continuous 1s to avoid confusion with frame delimiters. \tn 
% Row Count 12 (+ 4)
% Row 4
\SetRowColor{LightBackground}
{\bf{Clock-based (SONET)}} & Uses synchronization signals to mark frame boundaries. \tn 
% Row Count 15 (+ 3)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Cyclic Redundancy Check (CRC)}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Uses polynomial division to generate a checksum (CRC code).} \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Steps:} \tn 
% Row Count 3 (+ 1)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{1.	Choose a predefined generator polynomial (e.g., x$^{\textrm{3}}$ + x + 1 → 1011).\{\{nl\}\} 2.	Append n zeros to data (where n = degree of polynomial). \{\{nl\}\}3.	Divide modified data by polynomial (using XOR). \{\{nl\}\}4.	Append remainder (CRC) to original data.} \tn 
% Row Count 8 (+ 5)
% Row 3
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Advantage: Detects all single-bit, double-bit, and odd-length burst errors.} \tn 
% Row Count 10 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Hamming Code}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Adds redundant bits to detect and correct single-bit errors.} \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Steps:} \tn 
% Row Count 3 (+ 1)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{1.	Insert parity bits at positions that are powers of 2 (1, 2, 4, 8...). \{\{nl\}\} 2.	Calculate parity for overlapping bit groups.} \tn 
% Row Count 6 (+ 3)
% Row 3
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Example:} \tn 
% Row Count 7 (+ 1)
% Row 4
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{1. Data: 1001 \{\{nl\}\} 2. Encoded: \_ \_ 1 \_ 0 0 1 (positions 1,2,4 are parity bits) \{\{nl\}\}Calculate parity:} \tn 
% Row Count 10 (+ 3)
% Row 5
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{\{\{ar\}\}{\emph{ P1 (positions 1,3,5,7): ? + 1 + 0 + 1 → Even parity → 0 \{\{nl\}\}	}} P2 (positions 2,3,6,7): ? + 1 + 0 + 1 → Even parity → 0 \{\{nl\}\}P4 (positions 4,5,6,7): ? + 0 + 0 + 1 → Odd parity → 1} \tn 
% Row Count 15 (+ 5)
% Row 6
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Final Hamming code: 0011001} \tn 
% Row Count 16 (+ 1)
% Row 7
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Error Correction: Receiver recalculates parity to locate and flip the erroneous bit.} \tn 
% Row Count 18 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{0.96071 cm} x{1.04425 cm} x{1.04425 cm} x{1.12779 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{4}{x{5.377cm}}{\bf\textcolor{white}{Flow Control Methods}}  \tn
% Row 0
\SetRowColor{LightBackground}
{\bf{Method}} & {\bf{Efficiency}} & {\bf{Complexity}} & {\bf{Best For}} \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
Stop \& Wait & Low & Low & Low-speed links \tn 
% Row Count 4 (+ 2)
% Row 2
\SetRowColor{LightBackground}
Go back N & Medium & Medium & Moderate \tn 
% Row Count 5 (+ 1)
% Row 3
\SetRowColor{white}
\seqsplit{Selective} Rep & High & High & \seqsplit{High-speed} \tn 
% Row Count 7 (+ 2)
% Row 4
\SetRowColor{LightBackground}
Leaky Bucket & \seqsplit{Controlled} & Medium & Traffic shaping \tn 
% Row Count 9 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}----}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Switching Techniques}}  \tn
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Switching is a technique used to transmit data across a network from source to destination. It determines how data is routed and delivered between network devices% Row Count 4 (+ 4)
} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{1.51041 cm} x{1.55618 cm} x{1.51041 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{3}{x{5.377cm}}{\bf\textcolor{white}{Comparison of Switching Techniques}}  \tn
% Row 0
\SetRowColor{LightBackground}
{\bf{Circuit}} & {\bf{Packet}} & {\bf{Message}} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
Dedicated \seqsplit{communication} path,before data transfer. & Data is divided into packets sent \seqsplit{independently} & Entire message is stored and forwarded. \tn 
% Row Count 5 (+ 4)
% Row 2
\SetRowColor{LightBackground}
Consistent and reliable & Efficient use of bandwidth. & No need for a dedicated path. \tn 
% Row Count 8 (+ 3)
% Row 3
\SetRowColor{white}
Wastes bandwidth when idle. & Packets may arrive out of order. & Delays due to \seqsplit{store-and-forward}. \tn 
% Row Count 11 (+ 3)
% Row 4
\SetRowColor{LightBackground}
Telephone networks & Internet, VoIP & Email systems \tn 
% Row Count 13 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}---}
\SetRowColor{LightBackground}
\mymulticolumn{3}{x{5.377cm}}{\seqsplit{Technique	Description	Advantage	Disadvantage	Use} Case}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}---}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{0.9154 cm} x{2.56312 cm} x{1.09848 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{3}{x{5.377cm}}{\bf\textcolor{white}{Error Types}}  \tn
% Row 0
\SetRowColor{LightBackground}
{\bf{Error Type}} & Description & Example \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
\seqsplit{Single-bit} & One bit is flipped (0→1 or 1→0) & 010 → 011 \tn 
% Row Count 4 (+ 2)
% Row 2
\SetRowColor{LightBackground}
Burst Error & Multiple consecutive bits are corrupted & 001100 → 110011 \tn 
% Row Count 6 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}---}
\SetRowColor{LightBackground}
\mymulticolumn{3}{x{5.377cm}}{Types of Errors in Networking}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}---}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Error Detection Techniques}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{\{\{br\}\}Parity Check} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Adds an extra bit (parity bit) to make the total number of 1s even (even parity) or odd (odd parity).} \tn 
% Row Count 4 (+ 3)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{1.14425 cm} x{1.64772 cm} x{1.78503 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{3}{x{5.377cm}}{\bf\textcolor{white}{Comparison: CSMA/CD vs. CSMA/CA}}  \tn
% Row 0
\SetRowColor{LightBackground}
{\bf{Feature}} & {\bf{CSMA/CD (Ethernet)}} & {\bf{CSMA/CA (Wi-Fi)}} \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
Medium & Wired & Wireless \tn 
% Row Count 3 (+ 1)
% Row 2
\SetRowColor{LightBackground}
Collision Handling & Detects collisions & Avoids collisions \tn 
% Row Count 5 (+ 2)
% Row 3
\SetRowColor{white}
Duplex Mode & Half-duplex & Doesn't require full-duplex \tn 
% Row Count 7 (+ 2)
% Row 4
\SetRowColor{LightBackground}
Mechanism & Listens while transmitting & Uses RTS/CTS/ACK \tn 
% Row Count 9 (+ 2)
% Row 5
\SetRowColor{white}
\seqsplit{Efficiency} & Faster in wired networks & Slower due to overhead \tn 
% Row Count 11 (+ 2)
% Row 6
\SetRowColor{LightBackground}
Backoff Algorithm & Binary Exponential & Similar, but with DIFS/SIFS \tn 
% Row Count 13 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}---}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Checksum}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Sender computes a checksum (sum of data bytes) and appends it to the data. Receiver recalculates and compares. \{\{nl\}\}Steps:} \tn 
% Row Count 3 (+ 3)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{1.	Divide data into fixed-size segments (e.g., 16-bit words).\{\{nl\}\}2.	Sum all segments (ignore overflow).\{\{nl\}\} 3.	Take 1's complement (invert bits) → Checksum.\{\{nl\}\} 4.	Append checksum to data.} \tn 
% Row Count 7 (+ 4)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Limitation: Weak against certain errors (e.g., reordered data).}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}


% That's all folks
\end{multicols*}

\end{document}