CSE 328 / 329 · Stallings Ch. 2–7, 19

Computer
Networks · Study Guide

Socratic walkthroughs, flashcards & practice quizzes for the full course
قبل ما تبدا سمي الله و صلي عالنبي

Welcome 👋

This interactive study guide is designed to help you master Computer Networks — protocols, signals, error control, flow control, HDLC and routing — built on Stallings' textbook and Prof. Hossam Kasem's lectures. Navigate through the modes below:

  • 📖 Tutorial Mode: Socratic walkthroughs of OSI/TCP-IP, transmission impairments, CRC, Hamming, ARQ, sliding window, HDLC and routing — with try-it checks and worked examples.
  • 🎴 Flash Cards: Quick-recall decks of definitions, formulas, register fields, and one-liner facts.
  • 🎯 Professor's Focus: Every Q & A and solved numerical from Prof. Kasem's Midterm Revision Guide (Part 1, L1–L4) and the Advanced Final Study Companion (Part 2, L5–L10) — pick a part from the home page.
  • ⚡ Practice Quiz: Exam-style MCQs drawn from lectures, sheets, assignments & revision.

💡 Pro-Tip: Press Ctrl+K to search across tutorials and questions. The floating 📋 Cheat Sheet at the bottom-right has Shannon/Nyquist, Hamming layout, HDLC frame format and routing rules.

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Tutorial Mode
Socratic walkthroughs of every lecture with try-it checks
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Flash Cards
Quick-recall decks of terms, formulas & one-liner facts
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Professor's Focus
Every Q & A and solved numerical from both Midterm & Final revision guides
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Practice Quiz
Exam-style MCQs with hints, explanations & mistake tracking
Professor's Focus

Pick a revision part

Each part is a self-contained Q & A + worked-numerical deck drawn from Prof. Kasem's revision documents.

P1
Part 1 · Midterm Revision
Lectures 1–4 — communication model, OSI/TCP-IP, impairments, Shannon/Nyquist, thermal noise.
21 Q & A 6 numericals
P2
Part 2 · Advanced Final
Lectures 5–10 — parity & checksum, CRC circuits, HDLC, sliding window, TSI, routing.
Deep diagrams Mod-2 traces
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📋 Cheat Sheet
Check formulas, truth tables, and registers anytime!
TUTORIAL MODEChoose a topic
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Protocol Architecture & OSI (Lectures 1–2)
Need for protocols · 7-layer OSI · TCP/IP 5-layer · PDUs · TCP vs UDP · overhead
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Data Transmission & Signals (Lecture 3)
Analog vs digital · impairments · Shannon · Nyquist · thermal noise · attenuation
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Error Detection — Parity, Checksum, CRC (Lecture 5)
Parity weaknesses · CRC polynomials · modulo-2 division · Internet checksum
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Error Correction — Hamming (Lecture 6)
dmin → detect/correct · parity positions & coverage · syndrome decoding
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Flow Control & ARQ (Lecture 7)
Stop-and-wait · sliding window · utilization · Go-Back-N · Selective Reject
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HDLC Protocol (Lectures 7–8)
Frame format · bit stuffing · I/S/U frames · NRM/ABM/ARM · SABM & UA
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Routing & WAN (Lecture 10)
Fixed / Flooding / Random / Adaptive · Dijkstra vs Bellman-Ford · ARPANET history
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LINKSMore Practice
Want to go deeper?
  • 📕 Stallings textbook: Data and Computer Communications — chapters 2, 3, 6, 7, 19.
  • 🎯 Professor's Focus tab: the entire Midterm Revision Q & A document.
  • 📋 Cheat Sheet: open the floating button (bottom-right) for Shannon/Nyquist, Hamming positions, HDLC frame layout, and routing strategies.
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FLASH CARDS
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PROFESSOR'S FOCUSFull Revision Guide (Parts 1 & 2)
Every Q&A and solved numerical Prof. Kasem highlighted — Lectures 1–10

Items drawn from the CSE 328 Midterm Revision Guide and the Advanced Final Exam Study Companion (Part 2). Theory first, then solved numericals. Click any item to expand.

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📘 Theoretical Q & A

🧮 Solved Numerical Problems

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📋 Exam Reference Sheet

Protocol Architecture & OSI / TCP-IP

OSI 7 layers (top→bottom): Application · Presentation · Session · Transport · Network · Data Link · Physical.

TCP/IP 5 layers: Application · Transport · Internet · Network Access · Physical.

OSITCP/IPPDUExample
7 ApplicationApplicationdataHTTP, FTP, SMTP, DNS
6 PresentationdataTLS, JPEG, ASCII
5 SessiondataNetBIOS, RPC
4 TransportTransportsegment / datagramTCP, UDP
3 NetworkInternetpacketIP, ICMP, ARP
2 Data LinkNetwork AccessframeEthernet, HDLC, PPP
1 PhysicalPhysicalbitcables, fiber, radio

Protocol elements: Syntax · Semantics · Timing.

TCP vs UDP: TCP header ≥ 20 B, reliable, ordered. UDP header = 8 B, best-effort.

Signals & Transmission

Shannon: C = B · log2(1 + SNR)
SNR linear; from dB: SNR = 10SNRdB/10
Nyquist: R = 2B · log2(M)
noise-free channel
Thermal noise: N = k · T · B
k = 1.38 × 10−23 J/K · T in K
AttenuationdB = 10 · log10(Pin / Pout)
+3 dB ≈ ×2 · +10 dB = ×10

Impairments: Attenuation · Limited bandwidth · Delay distortion · Noise (thermal, intermod, crosstalk, impulse).

Error Detection & Correction

Parity: catches all odd-count errors; misses all even.

CRC: append n zeros, modulo-2 divide by P(X), remainder = FCS. Modulo-2 add = XOR.

Hamming positions: P1, P2, D, P4, D, D, D, P8, …

Coverage rule: Pi covers every position whose binary index has bit i set.

2r ≥ m + r + 1
detect ≤ dmin − 1 · correct ≤ ⌊(dmin − 1)/2⌋

Flow Control, ARQ & HDLC

Stop-and-wait: U = 1 / (1 + 2a)
a = Tprop / Tframe
Sliding window: U = W / (1 + 2a) if W < 1 + 2a; else 1

Seq-number limits (k bits): Go-Back-N W ≤ 2k − 1 · Selective Reject W ≤ 2k−1.

HDLC frame: Flag · Address · Control · Info · FCS · Flag.

Frame types: I · S (RR, RNR, REJ, SREJ) · U (SABM, UA, DISC, FRMR).

Bit stuffing: after every five 1s insert a 0.

Modes: NRM · ABM (most common, no polling) · ARM.

Routing & WAN

StrategyInfo neededStrengthWeakness
Fixedstatic tablesimpleno reaction
Floodingnonerobust, broadcastsload
Randomnonesimplesuboptimal
Adaptivelive statereactscan oscillate

Algorithms: Dijkstra (full topology) vs Bellman-Ford (neighbor distance vectors).

ARPANET: Gen 1 Bellman-Ford/queue · Gen 2 Dijkstra/delay · Gen 3 averaged delay.

WAN switching: Circuit · Packet (datagram/VC) · Frame Relay · ATM (53-byte cells).

Midterm Focus — Key Formulas

Data sizes: Total bits = images × pixels × bpp. Video bps = bits/frame × fps.

Shannon: C = B · log2(1 + SNR)
Nyquist: R = 2B · log2(M)
Thermal noise: N = k · T · B
AttenuationdB = 10 · log10(Pin / Pout)

Quick recall: log2(16) = 4 · log2(64) = 6 · 100.3 ≈ 2 · K = °C + 273.

OSI mnemonic: All People Seem To Need Data Processing.