Networks and IT Infrastructure

Networks and IT Infrastructure

IT infrastructure is the foundation upon which all information systems are built. It encompasses the hardware, software, networks, data management, and services required to deliver IT capabilities to an organisation. Without reliable, well-designed infrastructure, even the best applications and data strategies will fail. Understanding infrastructure is therefore essential for any business professional involved in digital strategy or operations.

The Evolution of IT Infrastructure

IT infrastructure has evolved through a series of distinct eras, each representing a fundamental shift in how computing power is delivered:

1. Mainframe era (1950s–1970s) — large, centralised computers serving many users through dumb terminals; computing was shared and expensive, owned by large institutions only
2. Personal computer era (1980s–1990s) — desktop computers gave individuals their own processing power; computing became decentralised but created new data silos and integration challenges
3. Client-server era (1990s–2000s) — desktop client machines were networked to shared servers; processing was split between client and server; this enabled networked applications and centralised data management while leveraging local processing
4. Cloud computing era (2010s–present) — computing power, storage, and software are delivered as on-demand services via the internet; organisations can access infrastructure without owning it

Network Types

Networks are classified by their geographic scope:

• PAN (Personal Area Network) — the smallest scale; connects personal devices over very short distances (e.g. Bluetooth connecting a smartphone to headphones)
• LAN (Local Area Network) — covers a limited physical area such as a home, school, office floor, or building; typically owned and managed by a single organisation; enables sharing of files, printers, and internet access among connected devices
• MAN (Metropolitan Area Network) — covers a city or large campus; geographically separated locations within the same metropolitan area; often used by universities, municipalities, or businesses with multiple city locations
• WAN (Wide Area Network) — covers large geographic areas, potentially global; enables organisations to carry out business regardless of geographic location; the internet is the largest and most important WAN; organisations use private WANs to connect geographically dispersed offices securely

Network Topologies

A network topology describes the physical or logical arrangement of nodes and connections in a network:

• Bus topology — all devices connected to a single central cable (the bus); simple but if the bus fails, the entire network fails
• Star topology — all devices connect to a central hub or switch; failure of a single device does not affect others; easy to manage and expand; most common in modern LANs
• Ring topology — devices connected in a closed loop; data travels in one direction; failure of one device can disrupt the whole network
• Mesh topology — each device connects to multiple others; highly resilient (multiple paths exist); complex and expensive; used in critical infrastructure and WANs
• Tree (hierarchical) topology — a hybrid of star and bus; organised in a tree-like hierarchy; scales well for large networks

Intranet, Extranet, and the Internet

• Internet — the global public network of networks; uses TCP/IP protocols; accessible to anyone with a connection
• Intranet — a private network using internet technologies but restricted to an organisation's employees; used for internal communication, document sharing, and applications
• Extranet — an intranet extended to allow selected outside parties (e.g. business partners, key customers, suppliers) to access certain internal resources; requires authentication and access control

Cloud Computing

Cloud computing is the delivery of computing services — including servers, storage, databases, networking, software, analytics, and intelligence — over the internet, enabling faster innovation, flexible resources, and economies of scale. Organisations obtain computing power and software over the internet without owning the underlying infrastructure.

Cloud services are typically delivered in three models:

• IaaS (Infrastructure as a Service) — raw computing infrastructure on demand (virtual machines, storage, networking)
• PaaS (Platform as a Service) — a platform for developing and deploying applications without managing underlying infrastructure
• SaaS (Software as a Service) — complete software applications delivered via browser subscription (e.g. Microsoft 365, Salesforce, ERP systems)

IT Infrastructure and Business Strategy

IT infrastructure is not merely a technical concern — it is a strategic one. Infrastructure should support the firm's business and information systems strategy, evolving as new technologies emerge and as business requirements change. Key principles include:

• Infrastructure choices directly affect an organisation's ability to respond to competitive threats and opportunities
• Infrastructure decisions involve significant capital and operational commitments that constrain future options
• Cloud infrastructure offers greater flexibility and scalability than on-premise alternatives
• Infrastructure resilience, security, and compliance are board-level concerns, not just technical ones