Network Hardware: Switches, Routers, WAPs, and NICs

This lesson covers the key hardware components used in computer networks, as required by OCR J277 Section 1.3.1. You need to understand the purpose of switches, routers, wireless access points (WAPs), and network interface cards (NICs).

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Network Interface Card (NIC)

A NIC (Network Interface Card) is a hardware component that allows a device to connect to a network. Every device that connects to a network must have a NIC.

Feature	Detail
Purpose	Enables a device to send and receive data over a network
Location	Built into the motherboard of most modern devices, or added as an expansion card
Types	Wired NIC (Ethernet port) and wireless NIC (WiFi adapter)
MAC address	Each NIC has a unique MAC (Media Access Control) address — a permanent identifier assigned during manufacture

MAC Address

A MAC address is a 48-bit address written in hexadecimal, for example: A4:B1:C2:D3:E4:F5

• Every NIC has a unique MAC address — no two are the same worldwide.
• MAC addresses are used to identify devices on a local network (LAN).
• They operate at the data link layer of the network.

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Switch

A switch is a networking device that connects multiple devices within a LAN and directs data to the specific device it is intended for.

Feature	Detail
Purpose	Connects devices in a LAN and forwards data to the correct recipient
How it works	Maintains a table of MAC addresses; when data arrives, it reads the destination MAC address and sends the data only to that port
Advantage over a hub	A switch sends data only to the intended device; a hub sends data to all connected devices (less efficient)
Location	Central device in a star topology

Switch vs Hub

Feature	Switch	Hub
Data delivery	Sends to specific device only	Sends to all connected devices
Efficiency	High — reduces unnecessary traffic	Low — generates more traffic
Collisions	Rare	Common
Security	Better — data only goes to intended recipient	Poor — all devices see all data
Cost	More expensive	Cheaper
Modern use	Standard in most networks	Largely obsolete

OCR Exam Tip: If asked about the difference between a switch and a hub, the key point is: a switch sends data only to the intended recipient using MAC addresses, while a hub broadcasts data to all devices.

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Router

A router is a networking device that directs data between different networks. Routers are essential for connecting a LAN to the internet (a WAN).

Feature	Detail
Purpose	Forwards data packets between different networks (e.g. from LAN to WAN)
How it works	Reads the IP address of incoming packets and determines the best route to the destination network
Routing table	Maintains a table of network addresses and the best paths to reach them
NAT	Performs Network Address Translation — translates private IP addresses (LAN) to a public IP address (internet)
DHCP	Often assigns IP addresses to devices on the network automatically

Key Difference: Switch vs Router

Feature	Switch	Router
Operates on	MAC addresses (within a LAN)	IP addresses (between networks)
Connects	Devices within the same network	Different networks together
Example	Connecting PCs in a school LAN	Connecting the school LAN to the internet

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Wireless Access Point (WAP)

A WAP (Wireless Access Point) is a device that allows wireless devices to connect to a wired network using WiFi.

Feature	Detail
Purpose	Provides a wireless connection point for devices to join the network
How it works	Receives data wirelessly from devices (laptops, phones, tablets) and forwards it to the wired network (and vice versa)
Connection	The WAP itself is connected to the switch/router via an Ethernet cable
Range	Typically 30-50 metres indoors; multiple WAPs can be used for larger areas
Security	Should use encryption (WPA2 or WPA3) to protect wireless data

Home Router vs WAP

In many homes, the router also includes a WAP and a switch — it is an all-in-one device. In larger networks (schools, businesses), these are typically separate devices for better performance and coverage.

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How the Hardware Works Together

Consider a school network:

1. Each student's computer has a NIC that connects it to the network (wired or wireless).
2. Wired computers connect to a switch, which directs data to the correct device on the LAN.
3. Wireless devices (tablets, laptops) connect to a WAP, which bridges them to the wired network.
4. A router connects the school LAN to the internet (WAN), directing data packets between the two networks.

flowchart LR
  PC["Student PC"] -->|NIC| SW["Switch"]
  TAB["Tablet"] -->|WiFi| WAP["WAP"]
  WAP --> SW
  SW --> RT["Router"]
  RT --> NET["Internet (WAN)"]

flowchart LR
  PC["Student PC<br/>NIC + MAC"] -->|Ethernet| SW["Switch<br/>MAC table"]
  TAB["Tablet<br/>Wireless NIC"] -->|WiFi| WAP[Wireless Access Point]
  WAP -->|Ethernet| SW
  SW -->|Frames| RT["Router<br/>IP + NAT + DHCP"]
  RT -->|Packets| NET((Internet / WAN))

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Summary of Network Hardware

Device	Purpose	Key Detail
NIC	Connects a device to the network	Has a unique MAC address
Switch	Connects devices within a LAN; directs data to the correct device	Uses MAC addresses
Router	Connects different networks; directs data between networks	Uses IP addresses
WAP	Provides wireless access to a wired network	Uses WiFi; connected to switch via Ethernet

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Summary