ü A Network is a set of devices (nodes) interconnected by communication links.

ü A node can be a computer, printer, or any other device capable of sending and/or receiving data generate by other nodes on the network.

ü The computers on a network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams.

ü These links connecting the devices are called Communication channels (transmission medium).

2. Computer Network Architecture

ü Computer Network Architecture is defined as the physical and logical design of the hardware, software, protocols, and media of the transmission of data.

ü Network architecture generally refers to design of computer network or communications network.

ü Simply we can say that how computers are organized and how tasks are allocated to the computer.

Types of Computer Network Architecture:

The two most popular computer architectures are-

 

 

1.P2P (Peer to Peer) Computer Architecture

ü These peers are connected to each other with help of Internet.

ü Files might be shared directly without requirement of central server among these systems on the network.

ü P2P network, tasks are allocated at each and every device available on network.

ü Peer-To-Peer network is useful for small environments, usually up to 10 computers.

ü Peer-To-Peer network has no dedicated server.

ü There is also no separate division as clients and servers.

ü Each and every computer in this network are treated same and equally and might send even receive message directly.

ü This P2P network is generally useful in various fields such as education, business, military, etc.

Advantages:

ü It is inexpensive as it does not contain any dedicated server.

ü If one computer stops working but, other computers will not stop working.

ü P2P is very simple and not complex.

ü It is easy to set up and maintain as each computer manages itself.

Disadvantages:

ü It cannot back up the data as the data is different in different locations.

ü It has a security issue as the device is managed itself. This is because message that is sent flows freely among connected computers.

2.Client-Server Computer Architecture.

ü Client/Server network is a network model designed for the end users called clients, to access the resources such as video, songs, etc. from a  Server (central computer).

ü The central controller is known as a server while all other computers in
the network are called clients.

ü It is type of system where clients are connected to server to just share or use
resources such as files, directories, printer, etc.

ü A server performs all the major operations such as security and network
management.

ü A server is responsible for managing all the resources such as files,
directories, printer, etc.

ü All the clients communicate with each other through a server. For example, if
client1 wants to send some data to client2, then it first sends the request to
the server for the permission. The server sends the response to the client1 to
initiate its communication with the client2.

Advantages:

ü We can back up the data easily due to centralized system.

ü Due to dedicated server that improves the overall performance of the whole system.

ü Security system is better in Client/Server network as a single server administers the shared resources.

ü It also boosts the speed of the sharing resources.

ü NOS (Network Operating System) is provided by server to provide resources to many users that request them.

Disadvantages:

ü It is expensive as it requires the server with large memory size.

ü The cost of Network Operating System (NOS) is very high.

ü It requires a dedicated network administrator to manage all the resources.

ü If any how server goes down or crashes, entire will be affected by this.

 

3.Line Configuration

ü Line configuration refers to the way two or more communication devices attached to a link.

ü Line configuration is also referred to as connection. 

ü A Link is the physical communication pathway that transfers data from one device to another.

ü For communication to occur, two devices must be connected in same way to the same link at the same time.

There are two possible line configurations.
1. Point-to-Point Connection.
2. Multipoint Connection.

1.Point-to-Point Connection:  

ü It is a protocol which is used as a communication link between two devices.

ü It is simple to establish.

ü The most common example for Point-to-Point connection (PPP) is a computer connected by telephone line.

ü We can connect the two devices by means of a pair of wires or using a microwave or satellite link.

ü Example: Point-to-Point connection between remote control and Television for changing the channels.

2.Multipoint Connection:

ü It is also called Multidrop configuration.

ü In this connection two or more devices share a single link.

ü There are two kinds of Multipoint Connections:

· Spatial Sharing-If the links are used simultaneously between many devices, then it is spatially shared line configuration.

· Temporal (Time) Sharing-If user takes turns while using the link, then it is temporal shared line configuration.

4. Network Strategies

ü A network strategy consists of your plan for building and managing a network
of partners in a way best suited to meet your shared goals.

ü It focuses on the considerations of how you will build your network, in terms of
what you will do, and would not do, to align your work with your goals.

Types of network strategies model:

       Four network strategies models: 

o terminal,

o client/ server,

o peer to peer and

o distributed processing network.

importance of network strategy

ü Networking will help you develop and improve your skill set and stay on top of the latest trends in your industry and job market.

ü Networking also helps you to advance your career and gives you access to more job opportunities.

5. Network Types

ü According to the distance, size and structure, computer network can be mainly classified into three categories.

ü LAN, MAN, and WAN are the 3 major types of networks designed to operate over the area they cover.

1. LAN (Local Area Network)

2.MAN (Metropolitan Area Network)

3.WAN (Wide Area Network)

ü There are many other types of Computer Networks also these are:  

a)PAN (Personal Area Network)

b)SAN (Storage Area Network)

c)EPN (Enterprise Private Network)

d)VPN (Virtual Private Network)

e)Wireless Local Area Network (WLAN)

f)Campus Area Network (CAN)

g)Storage Area Network (SAN)

h)System-Area Network (SAN)

i)Passive Optical Local Area Network (POLAN)

j)Enterprise Private Network (EPN)

k)Virtual Private Network (VPN)

l)Home Area Network (HAN)

LAN- (LOCAL AREA NETWAORK)-

v LAN means Local Area Network. LAN can be small, linking few computers.

v LAN is the most frequently used network.

v LAN is a data communication system within a building, plant, or campus, or between nearby building.

v LAN is used for connecting two or more personal computers through a communication medium such as twisted pair, coaxial cable, etc.

v It is less costly as it is built with inexpensive hardware such as hubs, network adapters, and ethernet cables.

v The data is transferred at an extremely faster rate in Local Area Network.

v Local Area Network provides higher security.

Types of LAN:

LAN can be classified as:

1)Client/Server

2)Peer to Peer (Workgroup)

LAN Features:

3)Standard PC Hardware

4)Resource Sharing

5)Common Applications

6)File Sharing

7)Data Security

8)Fault Tolerance

9)Centralized Security

MAN (METROPOLITAN AREA NETWORK)-

v A MAN is network with a size between a LAN and a WAN.

v It normally covers the area inside a town or a city.

v It is designed for customers who need a high-speed connectivity, normally to the Internet, and have endpoints spread over a city or part of city.

WAN (WIDE AREA NETWORK)

v A WAN is a data communication system spanning states, countries, or the whole world.

v Wide Area Network (WAN) connect LANs together between cities.

v The most common example of WAN is the Internet.

Advantage of Networking

1.Resources Sharing

2.High Reliability

3.High Speed