7.3 - Networks

7.3.1 Benefits and drawbacks of networks

Connecting Devices into Networks
Networks allow devices to share resources and communicate efficiently.

Benefits:
  • Resource sharing (files, printers, internet)
  • Improved communication
  • Centralised management and security
Drawbacks:
  • Security risks
  • Dependency on network availability
  • Setup and maintenance costs

7.3.2 Types of networks

Network Types by Coverage and Scale
Networks can differ by number of users, connection media, and coverage area.
  • PAN – Personal Area Network
  • LAN – Local Area Network
  • MAN – Metropolitan Area Network
  • WAN – Wide Area Network

7.3.3 Connectivity methods

Wired and Wireless Connectivity
Wired:
  • Copper / Ethernet – reliable and cost‑effective
  • Fibre‑optic – high speed and bandwidth
Wireless:
  • Wireless access points – flexible but susceptible to interference

7.3.4 Network topologies

Common Network Topologies
  • Star – Easy to manage, relies on a central device
  • Mesh – Highly resilient, complex and costly
  • Tree – Scalable hierarchical structure
Networks can be described as:
  • Physical – actual cable layout
  • Logical – data flow paths

7.3.5 Network models

Network Architecture Models
  • Client‑Server – centralised services
  • Thin Client – minimal local processing
  • Peer‑to‑Peer – equal devices sharing resources

7.3.6 Network components

Common Network Components
  • Server – provides services
  • Client – requests services
  • Router – directs network traffic
  • Network switch – connects local devices
  • Internet connection / backbone

7.3.7 OSI model

Seven‑Layer OSI Model and Functions
  1. Application – user-facing network services (e.g. web, email)
  2. Presentation – encryption, compression, data formatting
  3. Session – session setup, management, and termination
  4. Transport – data delivery, reliability, error handling
  5. Network – routing and logical addressing
  6. Data Link – frame creation and error detection
  7. Physical – transmission of raw bits over media

7.3.8 TCP/IP model

Four‑Layer TCP/IP Model and Functions
  • Application – combines OSI application, presentation, and session
  • Transport – reliable and unreliable delivery (TCP/UDP)
  • Internet – packet routing using IP addressing
  • Network – physical data transmission

OSI vs TCP/IP comparison

Comparing OSI and TCP/IP
OSI:
  • Conceptual reference model
  • Seven distinct layers
  • Used for teaching and troubleshooting
TCP/IP:
  • Practical implementation model
  • Four layers
  • Used by the internet

7.3.9 Data packets

Data Packet Transmission
Data packets contain headers, payload, and error‑checking data.

Packet switching can cause packet loss due to congestion.

Errors are detected using CRC (Cyclic Redundancy Check).

7.3.10 Network protocols

Common Network Protocols
Web: HTTP, HTTPS
Email: SMTP, POP, IMAP
Routing: RIP, OSPF
Application: FTP, SFTP, DHCP, DNS

7.3.11 Bandwidth and latency

Network Performance
Bandwidth is the amount of data that can be transmitted.

Latency is the delay in data transmission.

Both directly impact network and system performance.