What is Computer Network, Design and Topology

Computer networking is an engineering discipline that aims to study and analyze the communication process among various computing devices or computer systems that are linked, or networked, together to exchange information and share resources.

A computer network is a set of connected computers. Computers on a network are called nodes. The connection between computers can be done via cabling, most commonly the Ethernet cable, or wirelessly through radio waves. Connected computers can share resources, like access to the Internet, printers, file servers, and others. A network is a multipurpose connection, which allows a single computer to do more

Network Design              

Computer networks also differ in their design approach. The two basic forms of network design are called client/server and peer-to-peer. Client-server networks feature centralized server computers that store email, Web pages, files and or applications. On a peer-to-peer network, conversely, all computers tend to support the same functions. Client-server networks are much more common in business and peer-to-peer networks much more common in homes.

Topology

In communication networks, a topology is a usually schematic description of the arrangement of a network, including its nodes and connecting lines. Essentially, it is the topological structure of a network and may be depicted physically or logically. Physical topology is the placement of the various components of a network, including device location and cable installation, while logical topology illustrates how data flows within a network, regardless of its physical design. Distances between nodes, physical interconnections, transmission rates, or signal types may differ between two networks, yet their topologies may be identical.  The physical topology of a network is the actual geometric layout of workstations. There are several common physical topologies, as described below and as shown in the illustration.

Bus topology:

Alternatively referred to as a line topology, a bus topology is a network setup in which each computer and network device are connected to a single cable or backbone. The following sections contain both the advantages and disadvantages of using a bus topology with your devices.

Bus Topology

Advantages of bus topology

1. It works well when you have a small network.
2. Easiest network topology for connecting computers or peripherals in a linear fashion.
3.  Requires less cable length than a star topology

Disadvantages of bus topology

1. Difficult to identify the problems if the whole network goes down.
2. It can be hard to troubleshoot individual device issues.
3. Not great for large networks.
4. Terminators are required for both ends of the main cable.
5. Additional devices slow the network down.
6. If a main cable is damaged, the network fails or splits into two.

Star Topology:

Star networks are one of the most common computer network topologies. In its simplest form, a star network consists of one central switch, hub or computer, which acts as a conduit to transmit messages. This consists of a central node, to which all other nodes are connected; this central node provides a common connection point for all nodes through a hub. In star topology, every node (computer workstation or any other peripheral) is connected to a central node called a hub or switch.

Star Topology

Advantages of Star Topology

1. As compared to Bus topology it gives far much better performance, signals don’t necessarily get transmitted to all the workstations. A sent signal reaches the intended destination after passing through no more than 3-4 devices and 2-3 links. Performance of the network is dependent on the capacity of central hub.
2. Easy to connect new nodes or devices. In star topology new nodes can be added easily without affecting rest of the network. Similarly components can also be removed easily.
3. Centralized management. It helps in monitoring the network.
4. Failure of one node or link doesn’t affect the rest of network. At the same time it’s easy to detect the failure and troubleshoot it.

Disadvantages of Star Topology

1. Too much dependency on central device has its own drawbacks. If it fails whole network goes down.
2. The use of hub, a router or a switch as central device increases the overall cost of the network.
3. Performance and as well number of nodes which can be added in such topology is depended on capacity of central device.

Ring Topology:

A ring network is a network topology in which each node connects to exactly two other nodes, forming a single continuous pathway for signals through each node - a ring. Data travel from node to node, with each node along the way handling every packet.

Ring Topology

Advantages of Ring Topology

1. This type of network topology is very organized. Each node gets to send the data when it receives an   empty token. This helps to reduces chances of collision. Also in ring topology all the traffic flows in only one direction at very high speed.
2. Even when the load on the network increases, its performance is better than that of Bus topology.
3. There is no need for network server to control the connectivity between workstations.
4.  Additional components do not affect the performance of network.
5. Each computer has equal access to resources.

Disadvantages of Ring Topology

1. Each packet of data must pass through all the computers between source and destination. This makes it slower than Star topology.
2. If one workstation or port goes down, the entire network gets affected.
3. Network is highly dependent on the wire which connects different components.
4. MAU’s and network cards are expensive as compared to Ethernet cards and hubs

Mesh Topology:

A network setup where each computer and network device is interconnected with one another, allowing for most transmissions to be distributed, even if one of the connections go down. This topology is not commonly used for most computer networks as it is difficult and expensive to have redundant connection to every computer. However, this topology is commonly used for wireless networks. Below is a visual example of a simple computer setup on a network using a mesh topology.

Mesh Topology

Advantages of Mesh Topology

1.  Each connection can carry its own data load.
2. It is robust.
3. Fault is diagnosed easily.
4. Provides security and privacy.

Disadvantages of Mesh Topology

1. Installation and configuration is difficult.
2. Cabling cost is more.
3. Bulk wiring is required