Network Components

A network needs multiple components to connect computing devices to each other. The higher the number of devices or the longer the distance between devices, the more the components are required to transfer data between devices quickly, reliably, and securely. Not all networks need all components and complexity, but their processing may vary depending on whether they are connecting a home network (which is very small and simple) or a data center network (which is huge and complex). Some of the most commonly used components are described below.

Network Interface Controllers

A network interface controller (NIC) is a component that connects a computing device to the network. The NIC will have a connector to attach a cable for wired connections or an antenna for wireless transmission and reception and associated circuitry to send and receive data over the network. Each network interface controller has a unique identifier referred to as the Media Access Control (MAC) address which is unique across the billions of devices globally that can join any network.

Switches

In order to communicate with each other, two computing devices must be connected, directly or indirectly, over a wired or a wireless connection. When it is not practical to connect each device to every other device, networks use intermediary components to which each device connects. The intermediate device then acts as a bridge between devices within a network and further connects to intermediary devices in other networks for creating a connection between any two devices on all connected networks. Such intermediary components are referred to as switches. Switches perform multiple functions to enable seamless transfer of data between devices. They process the electronic signals that carry the data. For example, they may clean data signals, removing unnecessary noise that may be introduced during transmission. They may boost the signal to a higher power level so that it can be transmitted to other networks, possibly using a different transmission medium to help the signal cover longer distances without degradation.

Routers

A router is a networking device that forwards data packets between computer networks. Routers are added between switches in two different networks. Routers process the control information in data packets to determine the optimal path between the sending and the receiving computing devices for faster transmission. Routers are required to maintain a lot more information than switches and also do a lot more processing. Routing across networks with different characteristics and configurations is more complex than routing data within the same network. The simplest and familiar routers are home and small office routers that connect the home or small office network to the Internet and enable the exchange of data with other networks and devices, which are also connected to the Internet. More sophisticated enterprise routers connect large business networks across long distances and also connect them to the Internet. Depending on the distance between the source and destination devices, data packets may go through multiple routers, forwarded from one router to another based on the control information in the data packets.

Cables and Connectors

A Category-5 cable (commonly referred to as a Cat-5 cable) is cable made up of four pairs of twisted copper wire and is used for networking computers and other devices. The Cat-5 cable can provide high-speed data transmission rates up to 100 Mbps, over long distances without any data quality degradation, making it one of the most widely used cables in computer networks today.

A Cat-5 cable uses an RJ-45 connector which is a rectangular pronged plug with 8 pins arranged in two rows. This plug fits into the RJ-45 socket available on any device that can be connected on a wired network.

Modems

Modems (MOdulator-DEModulator) are network components that are required when the transmission media is not capable of sending digital signals. Digital data from the sending device is converted to analog signals (the modulation) to be transmitted over the analog medium. On the receiving end, another modem converts the analog signal to digital data (demodulation) for the receiving device to process. One example is the telephone line using an analog medium for data connections between a home network and the Internet. The transmission medium, such as optic fiber is capable of transmitting digital signals directly without any modems.

Firewalls

A firewall is a network device for controlling network security and access. When data is being exchanged between devices on a network, a firewall is managed by the same individual or enterprise. Here, security may not be a concern since the devices can be trusted. But most networks also need to communicate with devices on other networks and almost always with the Internet. While you connect devices across networks that are managed by other entities, it protects your network and systems from known or unknown malicious access. Firewalls sit between two networks and play the role of a gatekeeper. Modern firewalls are sophisticated in their ability to detect and prevent malicious network access. They allow network owners or administrators to define access and data rules to control what kind of data packets are allowed to be sent or received by the network with destination and source addresses. Basic firewalls can be software that is installed on your routers, but more sophisticated firewalls are a combination of dedicated hardware and software.