Computer Network and its Topology

What is Computer Network

What exactly is a computer network?

A computer network is a system that connects several independent computers in order for them to share information (data) and resources. Users can communicate more easily thanks to the integration of computers and other devices.

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A computer network is a collection of two or more computer systems that are linked together. A network connection can be established using either cable technology or wireless technology. Hardware and software are used to connect computers and devices in any network.

A computer network is made up of various types of nodes. Nodes in a computer network can include servers, networking hardware, personal computers, and other specialised or general-purpose hosts. They are identified using hostnames and network addresses.

Goal Of Networking:

• Programs do not have to run on a single system due to resource and load sharing.
• Cost savings – Printers, tape drives, and other peripherals can be shared by multiple machines.
• Reliability implies that if one machine fails, another can take its place.
• Capability to adapt (its ability to easily add more processors or computers)
• Postal service and communication (people living apart can work together)
• Access to Information (remote information access, access to the internet, e-mail, video conferencing, and online shopping)
• Connectivity for entertainment (online games, videos, etc.)
• Internet-based networking

Types of Networks

1. Division based on the communication medium 

• Wired Network: As we all know, the term "wired" refers to any physical medium comprised of cables. Copper wire, twisted pair, and fibre optic cables are all possibilities.

• Wireless Network: "Wireless" refers to media that is not wired and is made up of electromagnetic waves (EM Waves) or infrared waves. All wireless devices will have antennas or sensors. Wireless devices include cellular phones, wireless sensors, TV remotes, satellite disc receivers, and laptops with WLAN cards. A wireless network communicates using radiofrequency waves rather than wires.

2. Division based on area covered

• Local Area Network (LAN): A LAN is a collection of devices that are connected in a single physical location, such as a building, office, or home.

• MAN (Metropolitan Area Network): A metropolitan area network (MAN) is a computer network that connects computers within a metropolitan area, which can be a single large city, a collection of cities and towns, or any large area with multiple buildings. As an example, consider cable television networks.

• WAN (Wide Area Network): is a network that connects different countries or continents. The Internet, for example, allows users from all over the world to connect to a distributed system known as www.

What is Network Topology

A network topology is the arrangement of computer systems or network devices that are linked together.

What is Bus Topology

Every computer and network device in a bus topology network is linked to a single cable (Backbone Cable). A linear bus's topology is defined as having exactly two terminals with terminators.

Advantages: 

• The installation is easy.

• This topology works well when the network is small.

• The bus topology requires less cable than the mesh, star, and tree topologies.

• When compared to other topologies, this topology is highly cost-effective.

• When compared to a star topology, the required wire length is reduced.

Disadvantages: 

• This type of topology is unsuitable for huge networks.

• When compared to other topologies, this one is incredibly slow.

• It is tough to identify network faults.

• High pocket loss

• It is difficult to troubleshoot the problems for each device.

What is Ring Topology

The topology is called ring topology because it connects one computer to another, with the final one connecting to the first to form a circular lane. This topology is classified into two types: unidirectional and bidirectional. These topologies allow packets to go in just one direction, resulting in a unidirectional ring network, whereas others allow data to move in any direction, resulting in a bidirectional ring network.

Token passing is the most popular access technique in the ring topology.

• Token passing is a network access method in which a token is passed from one node to another.

• Token: A frame that passes via the network.

Working of Token passing

• A token travels through the network, being passed from computer to computer until it reaches its destination.

• The sender updates the token by include the address with the contents.

• The data is transmitted from one device to the next until the target address matches. When the token is received by the destination device, it sends an acknowledgement to the sender.

• A token is used as a carrier in a ring topology.

Advantages:

• In this topology, the possibility of collision is quite low.

• Installing and expanding it is cheap.

• There is no need for a central controller to manage node connectivity.

Disadvantages:

• A data packet in a Unidirectional Ring must pass through all nodes.

• To communicate with one another, all computers must be turned on.

• In this topology, troubleshooting is challenging.

• The installation or removal of stations between them can disrupt the entire topology.

• Less secure.

What is Star Topology

A star topology is a network arrangement in which every node is linked to a central hub, switch, or computer. The central computer is known as a server, and the peripheral devices connected to the server are known as clients.

Advantages:

• Efficient troubleshooting: When compared to a bus topology, troubleshooting in a star topology is quite efficient.

• Network control: The star topology makes it simple to add complex network control capabilities.

• Because each station is connected to the central hub through its own connection, a failure in one cable does not affect the entire network.

• It is easily scalable because more stations may be attached to the open ports on the hub.

• It is beneficial. High data rates

Disadvantages

• A central point of failure:If the central hub or switch fails, all connected nodes are unable to communicate with one another.

• The performance is based on a single concentrator, such as a hub or server.

What is Mesh topology

A mesh topology is a network setup where each computer and network device are interconnected with one another. Most communications can be transmitted using this topology even if one of the connections fails. It is a topology commonly used for wireless networks. A graphic representation of computers on a network with a full mesh topology is shown below.

Mesh Topology

In a full mesh topology, every computer in the network has a connection to each of the other computers in that network. The following formula can be used to calculate the number of connections in this network (n is the number of computers in the network): n(n-1)/2

At least two computers in the network have connections to multiple other computers in the network in a partial mesh topology. It is a low-cost method of implementing network redundancy. If one of the network's primary computers or connections fails, the rest of the network continues to function correctly.

Advantages

• Because multiple devices can transmit data at the same time, it manages large amounts of traffic.

• A single device failure does not interrupt the network or data transmission.

• Introducing additional devices does not interfere with data flow between existing devices.

Disadvantages

• It is more expensive to implement than other network topologies, making it a less desirable alternative.

• It is tough and time consuming to build and maintain the topology.

• The possibility of redundant connections exists, which adds to the high costs and potential for decreased efficiency.

What is Tree Topology

Also known as hierarchical topology, this is the most common form of network topology currently in use. Tree topology combines the features of bus topology and star topology

This topology divides the network into several layers/layers of the network. Mainly in LAN, a network is divided into three types of network devices.

• The Lowermost Layer is the access layer where computers or devices are attached. 

• The Middle Layer is known as the distribution layer, which works as a mediator between the upper layer and the lower layer

• The Highest Layer is known as the core layer and is central point of the network

Advantages

• provide transmission signals over long distances without being attenuated.

• We can easily add new devices to the existing network

• whole network is divided into segments known as star networks, which can be easily managed and maintained.

• Error detection and error correction are very easy

• The breakdown in one station does not affect the entire network

Disadvantages

• High cost: Devices required for broadband transmission are very costly.

• Failure in main bus cable will damage the overall network

• If new devices are added, then it becomes difficult to reconfigure.

What is Hybrid Topology

A hybrid topology is a type of network topology that is a combination of two or more network topologies, such as mesh topology, bus topology, and ring topology. Its use and choice are dependent on its deployment and requirements like desired network performance, the number of computers, their location.

Advantages

• This type of topology combines the benefits of different types of topologies in one topology.

• Can be modified as per requirement.

• It is extremely flexible.

• It is very reliable.

• Handles a large volume of traffic.

• It is used for creating a large network.

Disadvantages

• It is expensive.

• very complex.

• they require a lot of cables in the installation process.

• Installation is a difficult process.