Network Hardware (OCR A Level Computer Science)

Network Hardware

What Hardware is Needed in a Network?

Modem

• A modem (modulator-demodulator) is a device that modulates an analogue carrier signal to encode digital information and also demodulates a carrier signal to decode the transmitted information

• It enables a computer to transmit data over telephone or cable lines by converting digital signals into analogue and vice versa for receiving data

• It can be used for DSL, cable, or dial-up internet connections

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 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

• An important role of the router is to analyse data packets and direct them to their 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

Multiple networks connected by routers, represented by the blue circular objects

• 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

Cables

• Cables are the physical paths for data to travel between devices in a network

• Ethernet cables, like Cat5, Cat5e, and Cat6, are common types of network cables used for wired networks. They can transfer data at various speeds (10 Mbps, 100 Mbps, 1 Gbps, 10 Gbps)

• Fibre-optic cables use light to transmit data, offering much higher speed and larger data capacity

NIC (Network Interface Card)

• A network interface card (NIC) is a hardware component, 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

• Each network interface card has a unique identifier, which is known as a MAC address, which is created during the manufacturing process

Wireless Access Point (WAP)

• Wireless access points (WAPs) act as a central transmitter and receiver of Wi-Fi signals

• WAPs connect to the wired network from a fixed location using Ethernet or Fibre optic cable and project a Wi-Fi signal to a designated area

• In a large network, multiple access points are used to provide extensive coverage and handle many connections

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

• Switches are also used to connect several devices just like a hub; however, rather than sending data packets to all devices on the network, the switch will only send the data to its intended device

• 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