A2. Networks
THEME A: SYSTEM FUNDAMENTALS
Topic Overview
This module covers the purpose, benefits, and limitations of modern digital infrastructure, including the Internet, Cloud Computing, Distributed Systems, Edge Computing, and Mobile Networks. It also details the function of key network devices.
Table of Contents
Digital infrastructure: overview
Digital infrastructure refers to the physical and virtual systems that support the creation, transmission, storage, processing, and management of digital data.
It forms the foundation for modern digital services such as communication, cloud services, data analytics, online education, e-commerce, and automation.
Just as roads enable vehicles to move, digital infrastructure enables data packets to move reliably between devices and systems.
The Internet
Purpose
The internet is a global network of interconnected devices that communicate using standardized protocols. Its primary purpose is to enable reliable, fault-tolerant global communication and data exchange.
Benefits
- ✓ Enables worldwide communication and collaboration
- ✓ Provides access to vast information resources (text, audio, video)
- ✓ Supports online services such as education, banking, commerce, and entertainment
- ✓ Reduces operational costs for organizations through digital communication
- ✓ Allows centralized services to be accessed from anywhere
Limitations
- ⚠ Bandwidth and performance vary by location and congestion
- ⚠ Increasing demand places strain on infrastructure scalability
- ⚠ Security vulnerabilities expose users and organizations to cyber threats
- ⚠ Dependence on internet availability makes services vulnerable to outages
- ⚠ Critical systems relying on internet connectivity require high reliability and resilience
Cloud computing
Purpose
Cloud computing provides on-demand access to computing resources (storage, processing power, software) via the internet without requiring local infrastructure ownership.
Benefits
- ✓ Scalability: resources can be increased or reduced as needed
- ✓ Cost efficiency: pay-as-you-use model reduces upfront investment
- ✓ Accessibility: data and applications accessible from any location
- ✓ Supports collaboration for geographically distributed teams
- ✓ Built-in backup, redundancy, and disaster recovery
Limitations
- ⚠ Requires stable and reliable internet connectivity
- ⚠ Raises concerns about data security, privacy, and compliance
- ⚠ Latency can affect performance for real-time applications
- ⚠ Large data transfers can increase operational costs
- ⚠ Users share responsibility for securing cloud-stored data
Distributed systems
Purpose
A distributed system coordinates multiple independent computers (nodes) so they operate as one coherent system, sharing processing and storage tasks.
Benefits
- ✓ Improved performance through parallel processing
- ✓ Scalability by adding additional nodes
- ✓ Increased reliability and fault tolerance
- ✓ Efficient handling of large data sets
- ✓ Better resource utilization across systems
Limitations
- ⚠ Complex system design and maintenance
- ⚠ Difficulty ensuring data consistency across nodes
- ⚠ Increased latency due to inter-node communication
- ⚠ Larger security attack surface
- ⚠ Requires sophisticated coordination and fault-management algorithms
Edge computing
Purpose
Edge computing processes data near the source rather than in centralized data centres, minimizing delay and reliance on cloud connectivity.
Benefits
- ✓ Reduced latency for real-time applications
- ✓ Faster response times for critical systems
- ✓ Lower bandwidth usage by processing data locally
- ✓ Continued operation during connectivity loss
- ✓ Enhanced privacy by keeping sensitive data on-site
Limitations
- ⚠ Higher deployment and maintenance complexity
- ⚠ Increased security requirements across many devices
- ⚠ Higher initial infrastructure costs
- ⚠ Inconsistent computing capabilities across edge devices
- ⚠ Challenges maintaining data consistency across distributed locations
Mobile networks
Purpose
Mobile networks provide wireless connectivity for mobile devices over large geographic areas, supporting communication while users move.
Benefits
- ✓ Enables communication and internet access anywhere within coverage
- ✓ Supports voice, data, and multimedia services
- ✓ Increasing speeds and lower latency with newer generations (4G, 5G)
- ✓ Supports mobile applications, remote work, telemedicine, and IoT
- ✓ Facilitates constant connectivity in modern society
Limitations
- ⚠ Coverage gaps and signal interference
- ⚠ Network congestion affecting service quality
- ⚠ High infrastructure upgrade costs
- ⚠ Security vulnerabilities such as eavesdropping and data interception
- ⚠ Limited radio spectrum requiring careful management
Network Devices: Overview
Network devices are hardware components that manage, control, secure, direct, convert, and transmit data packets across networks.
Each device performs a specific role to ensure efficient, reliable, and secure communication between devices and networks.
Gateways
Function
A gateway connects networks that use different protocols or architectures, allowing communication between otherwise incompatible systems. Gateways often perform data translation, protocol conversion, and address mapping.
Key characteristics
- Operate across multiple layers of the TCP/IP model
- Translate data formats and protocols
- Often include security, filtering, and traffic management
- Act as entry and exit points between networks
Examples
- Connecting a private network to the internet using NAT
- Translating between SMTP and other messaging protocols
- Bridging VoIP networks with traditional telephone systems
Firewalls
Function
A firewall monitors and controls network traffic based on predefined security rules to prevent unauthorized access.
Hardware firewalls
- Physical devices placed at the network perimeter
- Protect entire networks
- Handle high traffic volumes efficiently
Software firewalls
- Installed on individual devices
- Provide application-level control
- Protect against internal threats
Modems
Function
A modem (modulator–demodulator) converts digital data into analogue signals for transmission over analogue media, and converts incoming analogue signals back into digital form.
- Bridge between digital networks and analogue transmission systems
- Used with telephone lines, cable, or satellite connections
- Enable internet connectivity via service providers
Network Interface Cards (NICs)
Function
A NIC allows a device to connect to a network by converting signals between the network medium and the computer’s internal digital format.
Key characteristics
- Handles data transmission and reception
- Converts electrical, optical, or radio signals into digital data
- Contains a unique MAC address
- Performs error detection (e.g., CRC)
Types
- Ethernet NICs
- Fibre-optic NICs
- Wireless (Wi-Fi) NICs
Routers
Function
A router forwards data packets between different networks by examining destination IP addresses and selecting the best path.
- Operate at the internet layer
- Maintain routing tables & use routing protocols (e.g., RIP)
- Connect LANs to WANs and the internet
- Support NAT, security policies, and traffic management
Switches
Function
A switch connects devices within a local area network (LAN) and forwards data frames based on MAC addresses.
- Operate at the link layer
- Maintain MAC address tables
- Reduce unnecessary traffic by forwarding data only to intended devices
- Handle broadcast and multicast traffic appropriately
Wireless Access Points (WAPs)
Function
A wireless access point (WAP) connects wireless devices to a wired network by converting Ethernet data into radio signals and vice versa.
- Extend network access without physical cables
- Support Wi-Fi security standards (WPA2, WPA3)
- Can be centrally managed & enable roaming
| Device | Primary Function |
|---|---|
| Gateway | Translates and connects different network protocols |
| Firewall | Filters traffic and enforces security rules |
| Modem | Converts digital ↔ analogue signals |
| NIC | Interfaces a device with a network |
| Router | Routes packets between networks |
| Switch | Directs traffic within a LAN |
| WAP | Provides wireless network access |
TCP/IP & Protocol Layers
The TCP/IP Model vs OSI
| TCP/IP Layer | Description | Protocols |
|---|---|---|
| Application | User interaction & data formatting | HTTP, FTP, SMTP, DNS |
| Transport | Error checking, packet sequencing (end-to-end) | TCP, UDP |
| Internet | Routing & IP addressing | IP (IPv4/IPv6), ICMP |
| Network Access | Physical transmission & MAC addressing | Ethernet, Wi-Fi (802.11) |
Exam Prep & Real-World Scenarios
Identify two functions of a router.
Model Answer:
- Directs data packets between different networks based on IP addresses.
- Assigns IP addresses to devices on a LAN (if acting as a DHCP server).
Explain why breaking data into packets is necessary for transmission.
Model Answer:
Breaking data into packets prevents large files from monopolizing the bandwidth ("blocking"), allowing multiple users to share the network simultaneously. Additionally, if a transmission error occurs, only the corrupted packet needs to be re-sent rather than the entire file, improving efficiency and reliability.
Real-World Scenario: Video Streaming
Scenario: A user experiences buffering while watching a 4K video. Explain the role of buffering and protocols involved.
Exam-Style Response:
Video streaming typically utilizes UDP (User Datagram Protocol) because speed is prioritized over perfect accuracy; dropping a few frames is preferable to pausing for re-transmission (latency).
Buffering occurs when the device pre-loads a portion of the video into memory. This ensures smooth playback even if network speed fluctuates or packets arrive out of order (jitter), preventing interruptions visible to the user.
Summary Comparison
| Infrastructure | Main purpose | Key benefit | Key limitation |
|---|---|---|---|
| Internet | Global data exchange | Universal connectivity | Security and scalability |
| Cloud computing | On-demand resources | Scalability and cost efficiency | Internet dependence |
| Distributed systems | Parallel processing | Performance and fault tolerance | Complexity |
| Edge computing | Local processing | Low latency | Management complexity |
| Mobile networks | Wireless connectivity | Mobility | Coverage and security |
IB-Style Exam Summary
Modern digital infrastructure provides the foundation for data communication, processing, and storage in contemporary computing systems. The internet enables global, fault-tolerant communication, while cloud computing offers scalable, cost-effective access to computing resources. Distributed systems improve performance and reliability by sharing workloads across multiple nodes, and edge computing reduces latency by processing data near its source. Mobile networks support wireless connectivity and mobility across large areas.
Network devices perform specialized roles to enable efficient and secure communication within and between networks. Gateways translate protocols between different networks, while firewalls protect networks by filtering traffic. Modems convert digital data for transmission over analogue media. Network interface cards allow devices to connect to networks using unique MAC addresses. Routers direct data packets between networks based on IP addressing, and switches manage traffic within local area networks using MAC address tables. Wireless access points extend network connectivity by enabling wireless communication. Together, these devices form the foundation of modern network infrastructure.