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ITM 253

Computer Networking

TU BITM · Semester 4 · BITM curriculum and programme regulation

Requirement
required
Credits
3
Study Guide
10 units available

Chapter notes

Authoritative study guide across 10 syllabus units

Open a unit to read its study notes.

Unit 1: Introduction to Data Communications· 3 LHs· ~4 marks

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Part 1: Core Concepts (2 Marks)

  • Data Communication: The exchange of data between two devices via a transmission medium governed by a set of communication protocols. Five core components: Message, Sender, Receiver, Transmission Medium, and Protocol.
  • OSI 7-Layer Reference Model: Application (7) →\to Presentation (6) →\to Session (5) →\to Transport (4) →\to Network (3) →\to Data Link (2) →\to Physical (1). Mnemonic: All People Seem To Need Data Processing.
  • TCP/IP Model (4/5 Layers): Application Layer, Transport Layer, Internet Layer, Network Access Layer.

Part 2: Structural Frameworks (10 Marks)

OSI vs TCP/IP Layer Mapping

OSI 7-Layer Model TCP/IP Protocol Suite
7. Application Layer Application Layer
6. Presentation Layer (HTTP, HTTPS, DNS, FTP, SMTP, SSH)
5. Session Layer
4. Transport Layer Transport Layer (TCP, UDP)
3. Network Layer Internet Layer (IPv4, IPv6, ICMP)
2. Data Link Layer Network Interface Layer
1. Physical Layer (Ethernet, Wi-Fi 802.11, ARP)

Part 3: Distinction Tables

Basis of Comparison OSI Model TCP/IP Model
Development Theoretical reference model developed by ISO. Practical protocol suite developed by ARPANET/DoD.
Layer Count 7 Layers. 4 or 5 Layers.
Approach Strict modular theoretical boundaries. Looser, pragmatic protocol-oriented design.

Part 4: Worked Problems & Exam Traps

Encapsulation and Decapsulation Protocol Data Units (PDUs)

  • Layer 7/6/5: Data
  • Layer 4 (Transport): Segment (TCP) / Datagram (UDP)
  • Layer 3 (Network): Packet (IP)
  • Layer 2 (Data Link): Frame (Ethernet MAC)
  • Layer 1 (Physical): Bits (0s and 1s)

Do not call Layer 2 PDUs “packets”. Layer 2 transfers Frames with physical MAC addresses; Layer 3 transfers Packets with logical IP addresses.