Physical Components of Computer Network

Pre-Requisite: Computer Networks

A computer network is a system that connects multiple independent computers in such a way that they can share information and resources. Some of the Physical Components of the Computer Network are mentioned below:

1. NIC(Network Interface Card)
2. HUB
3. Router
4. Modem
5. Switch
6. Nodes
7. Media

1. NIC(Network Interface Card): NIC or network interface card is a network adapter that is used to connect the computer to the network. It is installed in the computer to establish a LAN.  It has a unique id that is written on the chip, and it has a connector to connect the cable to it. The cable acts as an interface between the computer and the router or modem. NIC card is a layer 2 device which means that it works on both the physical and data link layers of the network model. There are two types of NIC: 

• Wired NIC: Cables and Connectors use Wired NIC to transfer data.
• Wireless NIC: These connect to a wireless network such as Wifi, Bluetooth, etc.

2. HUB: A HUB is a basically multi-port repeater. A hub connects multiple wires coming from different branches, for example, the connector in star topology which connects different stations. Hubs cannot filter data, so data packets are sent to all connected devices.  In other words, the collision domain of all hosts connected through Hub remains one.

3. Router:  A Router is a device like a switch that routes data packets based on their IP addresses. The router is mainly a Network Layer device. Routers normally connect LANs and WANs and have a dynamically updating routing table based on which they make decisions on routing the data packets. The router divides the broadcast domains of hosts connected through it. 

4. Modem: A Modem is a short form of Modulator/Demodulator. The Modem is a hardware component/device which can connect computers and other devices such as routers and switches to the internet. Modems convert or modulate the analog signals coming from telephone wire into a digital form that is in form of 0s and 1s. 

5. Switch: A Switch is a multiport bridge with a buffer and a design that can boost its efficiency(a large number of ports imply less traffic) and performance. A switch is a data link layer device. The switch can perform error checking before forwarding data, which makes it very efficient as it does not forward packets that have errors and forward good packets selectively to the correct port only.

6. Nodes: Node is a term used to refer to any computing devices such as computers that send and receive network packets across the network. Two Types of nodes are :

• End Nodes: These type of nodes is going to be the starting point or the end point of communication. E.g., computers, security cameras, network printers, etc.
• Intermediary Nodes: These nodes are going to be in between starting point or end point of the end nodes. E.g., Switches, Bridges, Routers, cell towers, etc.

7. Media: Also known as Link which is going to carry data from one side to another side. This link can be Wired Medium (Guided Medium) and Wireless Medium (Unguided Medium). It is of two types:

1. Wired Media
2. Wireless Media

Examples of Wired media are as follows:

Ethernet: Ethernet is the most widely used LAN technology, which is defined under IEEE standards 802.3. There are two types of Ethernet:

1. Ethernet straight-through cable (used for two different devices).
2. Ethernet crossover cable (used for two same devices).

Fibre Optic Cable: In this data is transferred in the form of light waves. 

Optic Fibre Cable

Coaxial Cable: Mainly used for audio and video communications. 

Coaxial Cable

USB Cable: USB Stands for Universal Serial Bus. Mainly used to connect PC and smartphones.

USB Cable

Examples of Wireless media are as follows:

• Infrared (E.g. short-range communication – TV remote control).
• Radio (E.g. Bluetooth, Wi-Fi).
• Microwaves (E.g. Cellular system).
• Satellite (E.g. Long range communications – GPS).