Network Hardware (Cambridge (CIE) A Level Computer Science): Revision Note

LAN hardware

Hub

• A hub is a networking device which is used to connect multiple devices in a network

• Hubs are "dumb" devices that pass on anything received on one connection to all other connections

• Because all data is sent to all devices, it can lead to network inefficiencies and security issues

• Hubs allow multiple other devices to be connected to them

• Hubs are generally much cheaper than switches, but:

  • When a hub receives a data packet, it will broadcast it to every device on the network

• This creates two potential issues:

  • As the information is being broadcast to every device, it will make unnecessary traffic, especially if there are a large number of devices

  • As every device will receive the data packet, security may be a concern

Switch

• A network switch is a networking device that connects devices on a computer network and uses packet switching to receive, process and forward data to the destination device

• Unlike a hub, a switch only sends data to the device it was intended for, which improves network efficiency

• This is done by each switch having a lookup table

• When a switch receives a data packet, it examines the destination MAC address and looks up that address in its lookup table

• Once it has found the matching MAC address, it will then forward the data packet to the corresponding port

Server

• A server is a powerful computer that provides services or resources to other devices on a network (called clients)

• Can manage and store files, host websites, control access to printers, or run applications

• Often kept in dedicated rooms or data centres due to their importance and high uptime requirements

• Designed to handle multiple requests at once and stay on 24/7

• Servers usually run specialist operating systems (e.g. Windows Server, Linux)

• Can be part of a LAN (local server) or accessed remotely over a WAN (cloud server)

• Examples include: file server, print server, web server, mail server

Network Interface Card (NIC)

• Historically a card inserted into a slot on the motherboard but now more likely to be built into the motherboard, that enables a device to connect to a network

• NICs have a built-in ethernet port and can be connected to a network via an ethernet cable

• It provides a dedicated, full-time connection to a network, converting the computer's data into a network-friendly format

• Every NIC has a unique identifier called a MAC address, used to identify the device on the network

• The primary function of a NIC is to send and receive data packets between the computer or device and the network

  

Wireless Network Interface Card (WNIC)

• Allows a device to connect to a wireless network (Wi-Fi)

• Often built into the motherboard of modern laptops, tablets, and smartphones

• Uses radio waves to send and receive data to/from a wireless router or access point

• Provides a dedicated connection to the network, without needing physical cables

• Supports standard wireless protocols like Wi-Fi 4, 5, or 6 depending on the model

• Has a unique MAC address used to identify the device on the network

• Converts the device’s data into a wireless signal suitable for network transmission

Wireless Access Point (WAP)

• Allows wireless devices to connect to a wired network

• Acts like a bridge between the wired and wireless parts of a network

• Commonly found in homes, schools, and offices as part of a Wi-Fi setup

• Often built into wireless routers, but can also be a separate device in larger networks

• Uses radio signals to send and receive data from wireless devices (e.g. laptops, phones)

• Extends the range of the wireless network, especially in large buildings

• Supports communication using standard Wi-Fi protocols (e.g. 802.11ac, 802.11ax)

Bridge

• Connects two separate network segments together

• Often used to join two LANs so they act as one larger network

• Operates at the data link layer (Layer 2) of the OSI model

• Can filter traffic by checking MAC addresses to decide if data should cross the bridge

• Helps reduce network traffic by only forwarding necessary data

• Commonly used in older or more complex network setups

Repeater

• Used to boost or regenerate signals in a network

• Helps extend the range of a wired or wireless signal

• Receives a weak signal and retransmits it at full strength

• Used when data needs to travel long distances without losing quality

• Often used in Wi-Fi range extenders to improve coverage in large buildings

• Operates at the physical layer (Layer 1) of the OSI model

Router

What is the role of a router?

• A router is a network hardware device that routes data from a local area network (LAN) to another network connection - it joins two networks together

• Routers analyse data packets and determine the best path for the packet to reach its destination

  • The header contains information about the packet

  • The payload is the actual data being sent

  • The IP address of both the sender and intended recipient is stored in the header of the data packet

• The router can often feature additional functionalities such as wireless networking, built-in firewalls for enhanced security, and network switch capabilities

• A router being used to connect a LAN to a WAN will have a public IP address, which has been assigned to it by an Internet Service Provider

• It is this public IP address that other routers use to identify and direct packets to the network

• If the data packet is coming into the LAN, the router will send the data packet to the specific device within its LAN that the packet is meant for

• If the packet is being sent from a device within the LAN, it will read the header of the packet to determine the intended destination IP address

  • It might have to travel through several routers before it gets to its destination

  • Each pass from router to router is called a hop

  • It will then forward the packet to its destination

• The network access device or ‘home hub’ used in your home network will have a router built into it

• Every router repeats this process the data packet passes through until it reaches its destination

• In addition to routing data between networks, routers can also perform other functions such as:

  • Assigning IP addresses to devices within the LAN

  • Filtering incoming traffic based on certain criteria, such as IP address, port number, or protocol type