Hello, we'll start by understanding what Computer Network is?
By definition a Computer Network is when two or more computers are connected together using a telecommunication system with the purpose of communicating and sharing resources.
With the help of networking it's convenient to make information accessible to anyone, anytime and anywhere.
So, Data Communication is an important part in our life.
When two digital devices exchange information by means of wired or wireless devices, it is known as data communication .
We can connect all these computers to each other with the help of communication links.
These communication links are made up different types of physical media including coaxial cable, fiber optics, copper wire, switches, modems and routers.
The basic requirements for communication between devices are as follows:
1) They has to be a sender and receiver.
2) Transmission Medium for movement of bits of information between communicating devices has to exist.
3) Protocol are required for proper communication.
4) Standard Data Representation: This as to be represent in order for data transmitted between devices international.
Networks are different type and these can be divided into Local Area Network (LAN), Wide Area Network (WAN), Metropolitan Area Networks (MAN) and Personal Area Network (PAN).
Let's consider each one of them at a time.
Local Area Network (LAN): This is a network that connects a relatively small number of machines in a small geographical locations.
An example of a Local Area Network would be a network with in a college or university.
Wide Area Network (WAN): Is a network that connects two or more local area networks over a potentially large geographic distance.
An example of Wide Area Network would be two colleges local area networks connected together.
Metropolitan Area Network (MAN): These are large computer networks usually spread out within a city.
An example of a Metropolitan Area Network would be a network large enough to cover a whole city.
Personal Area Network (PAN): Is a computer network used for communication among computer devices within for example someone's home.
Let's look at the uses of networks.
We can’t live without sharing information today and sometimes data files have to be shared simultaneously and have to be stored on server.
Software can be shared when installed on application servers with other devices on the network.
Peripheral device like printers and faxes can also be shared on a network.
Devices connected to a network allow instantaneous communication.
From taking place they allow Personal communication.
Email, Teleconferencing, Video conferencing, Audio conferencing and Data conferencing.
In addition they make it easier to back data up on removable media and the server too all in one step.
Network Topologies: Network Topologies can be described as the logical layout of wires and equipments.
It is important to be considered because the choice of topology affects the network performance, network size, network collision detection and much more.
Networks can be arranged in various topologies.
Let's looks at some of these topologies.
Who's start with the Bus topology: This is also refer to as the linear bus.
In this setup one wire call the backbone connects all the nodes in the network.
The backbone is terminated at both end.
Its main advantages in a network are:
1) Its easy to setup.
And two it requires small amount of wire.
Its disadvantages include: Thinks like its slow and its easy to crash.
The second type of topology to consider is the Star topology: Here, all nodes are connected to a hub or a switch.
Its advantages are: its very easy to setup.
Its main disadvantages are: if the single hub approach down it can cause the whole network to crash and its uses lots of cables.
The third type of topology to consider is the Ring topology: In the ring topology nodes are connected in a circle and data is transmitted using tokens and nodes must wait for token to send and to receive data.
The main advantages of the ring topology is that no data collision occurs between nodes will data is being transfer.
Its main disadvantages however is that its very slow network.
The fourth type of topology is the Mesh Topology: In the mesh topology all computers are connected to one another multiple times with different cable.
Its main advantages is that data will always be delivered.
And its disadvantages is that it require lot of cables and its tough to setup.
Network Hardware technologies.
Let's look at the technologies used to setup a network.
A number of devices are use to implementing networks.
These include Network interface cards, hubs, bridges and the gateway.
The Network Interface card or NIC allows to computer to connect to a network.
Let's look at some functions of the network interface card in relation to the sender and receiver devices.
The function of the network interface card at the sender are:
It receives data from the Network Layer.
It attaches the MAC address to the data packet being transmitted
It converts data into packets suitable for transfer over a particular network.
It provides the physical connection to the media.
Functions of a Network Interface Card at the destination.
It provides the physical connection to the media.
It translates signal into data.
It reads the MAC address to see if it matches its own address
If it does match it passes the data on to the Network Layer
The next device to consider is the hub: Hubs are used as a center of a star network and transmit packets to all nodes.
It allows multiple connection of devices.
Its advantages are: its relatively cheap and can connect to different media types.
Its disadvantages are: it cannot filter information and it passes packets to all connected segments.
After the hub the next device to discuss is the Bridge.
This device connect two or more local area network together.
It advantages are: it can extend network distances, uses MAC address to filter traffic, eases congestion and can connect different types of media.
Its disadvantages are: it broadcast packets but cannot filtered and its more expensive than a hub and a switch.
Next on the list is the Router: Routers are used to choose the best path to transmit data over a network.
Repeaters: These repeats signals that travels via long distance in a network.
Advantages of repeater are: they can connect different types of media and do not increase network traffic.
Their disadvantages include the fact that it extends the collision domain, it can not filter data and it can not connect different network architectures.
The Switch is a multiport bridge that functions at the data link layer.
It limits the collision domain and provide bridging.
Its more expensive than a hub and a bridge and its configuration of additional functions can be very complex.
The last is the Gateway : This can be a computer used to connect two different LANs and also connect different application protocols .
Thank you.