Describe the hardware that is used to support a LAN

2.1 Networks – The Internet

Objective: Describe the hardware that is used to support a LAN

1. Introduction to LAN hardware

A Local Area Network (LAN) connects computers and other devices within a limited area such as a home, office, or campus. The hardware that enables this connectivity can be grouped into three categories:

• Transmission media – the physical pathway for data.
• Network interface devices – convert data between digital form and the transmission medium.
• Network infrastructure devices – manage, direct, and protect traffic.

2. Transmission Media

The choice of media influences speed, distance, cost, and susceptibility to interference.

3. Network Interface Devices (NICs)

Every device that participates in a LAN must have a Network Interface Card (NIC) to attach to the chosen medium.

• Ethernet NIC – Provides RJ‑45 connector for twisted‑pair or RJ‑45/Fibre transceiver modules.
• Wireless NIC – Integrated Wi‑Fi adapter with antenna; may support multiple standards (802.11a/b/g/n/ac/ax).
• Fiber NIC – Uses SFP or SFP+ modules to connect to fibre optic cables.

NICs handle framing, error detection (CRC), and may offload tasks such as checksum calculation to improve performance.

4. Network Infrastructure Devices

4.1 Hubs

A hub is a simple, multi‑port repeater that broadcasts incoming frames to all other ports. It operates at the physical layer (Layer 1) and does not segment traffic.

• Pros: Very cheap, easy to set up.
• Cons: Causes collisions, limited bandwidth per port, obsolete in modern LANs.

4.2 Switches

Switches operate at the data‑link layer (Layer 2) and forward frames based on MAC addresses, creating separate collision domains for each port.

1. Learning: Switch builds a MAC address table by inspecting source addresses of incoming frames.
2. Forwarding: Uses the table to send frames only to the destination port.
3. Full‑duplex: Allows simultaneous send/receive, eliminating collisions.

Modern switches often include additional features:

• VLAN support – logical segmentation of a LAN.
• Port security – limits MAC addresses per port.
• Power over Ethernet (PoE) – supplies 48 V DC to devices such as IP phones and access points.

4.3 Routers

Routers operate at the network layer (Layer 3) and connect multiple LANs or a LAN to a WAN (e.g., the Internet). They examine IP addresses and make routing decisions.

• Static routing – manually configured routes.
• Dynamic routing – protocols such as OSPF, RIP, or EIGRP automatically exchange route information.
• Network Address Translation (NAT) – maps private LAN addresses to a public IP for Internet access.

4.4 Access Points (APs)

APs provide wireless connectivity to a wired LAN. They bridge the Wi‑Fi medium to the Ethernet backbone, handling authentication (WPA2/WPA3) and often supporting multiple SSIDs.

4.5 Modems

In a LAN that accesses the Internet via a broadband service, a modem converts digital signals from the LAN into the appropriate format for the ISP (e.g., DSL, cable, fiber). The modem is typically combined with a router in a single “gateway” device.

5. Example LAN Hardware Layout

The figure below summarises a typical small‑office LAN architecture.

6. Summary Checklist

• Choose appropriate transmission media based on speed, distance, and environment.
• Equip each device with a compatible NIC (wired or wireless).
• Use switches rather than hubs to avoid collisions and improve bandwidth.
• Deploy routers for inter‑network communication and NAT.
• Provide wireless coverage with access points, ensuring security settings are configured.
• Consider PoE switches to simplify power delivery to IP devices.