Communication Protocol:
A protocol is a set of rules that governs the transmission of data over a communication network. These rules provide a method for orderly and efficient exchange of data between sender and receiver. These rules include the guidelines that regulate the following characteristics of the network: access method, allowed physical topologies, types of cabling and speed of data transfer.
The most common protocols are:
- TCP/IP (Transmission control protocol/Internet protocol)
- SMTP (Simple mail Transfer protocol)
- POP (Post office protocol) FTP (File Transfer protocol)
- HTTP (Hyper text transfer protocol)
- Telnet Protocol (Tele Type Network Protocol)
Computer Network:
Networks are not new to us. We are familiar with postal networks, airlines networks, Television networks, business networks etc. Networks allow us to do various kinds of functions efficiently without much of effort. Evolution of computer has affected many areas of our life and computer network is one of the most popular and useful network in today's life, even we cannot think life without computer.
Computer network is a kind of data transfer arrangement which connects different types of computers and their attachments in such a way that they can communicate with each other by transferring any kind of data (picture, audio, video, document, clip etc.) in the form of electrical signals. For this it is not necessary that computers are near to each other or very far to each other.
SNA (System Network Architecture) was the first computer network developed by IBM to establish the link between its computers and it was limited to company only. This type of personal network is known as Intranet.
Advantages of Computer Network:
- It can share copies of single file among many users at the same time.
- It can share application of entire network, which reduce the cost of purchasing multiple software.
- It can share computer resources like printer, scanner, fax machine, modem etc.
- Faster and cheap communication possible.
- Data backup and recovery is possible.
Disadvantages of Computer Network:
- Virus can spreads each mostly through the computer network.
- Cyber crimes are originated from the computer network.
- With the help of computer network the anti social groups are able to launch their evil activities.
- It is expensive to setup.
- Lots of chances of technical problem in computer network.
- Special skilled manpower is required to operate and maintain computer network.
Types of Computer Network:
Computer network is classified into two types according to the architecture and geographical area.
1. On the basis of architecture
- Peer to peer network
- Client server network
2. On the basis of geographical area
- LAN (Local Area Network)
- MAN (Metropolitan Area Network)
- WAN (Wide Area Network)
On the basis of Architecture:
Based on the Architecture or services provided by the network, a network can be classified as Peer-to-peer network and Client/server network.
Peer–To–Peer Network:
Peer-To-Peer network can take both a client and a server role. There is no centralized control over shared resources, such as files or printer. Any individual machine can share its resources with any other computer on the same network, however and whenever its user chooses to do so. It in all the computers has equal access and responsibility in the network. It is also known as distributed network.
Advantages of Peer-To-Peer Network:
- Easy to install.
- Inexpensive.
- No central administrator who sets the network policies.
- No extra investment in server hardware or software required.
- Does not require dedicated workstation.
- Easy to troubleshoot.
Disadvantages of Peer-To-Peer Network:
- Less security.
- Not suitable for more than 10 users.
- Difficult to later time expand.
- Useful for only small organization.
- Each machine must be backed up individually to protect all shared data.
Client-Server Network:
An arrangement of computer to resources sharing and communicate to each other through a central device (server) to all workstations (Clients) is called client-server network. The server is a high capacity, high speed computer with a large memory. The clients/workstation can be simple microcomputers having their own application package with network operating system. The central server manages, organize and coordinate all network clients on the network. Clients request server for data and communicate to other clients. Different types of server provide different services. The most common service is provided by different servers are file services, print services, message services and database services.
Advantages of Client-server network:
- It covers large geographical area.
- High speed.
- Centralize the network management
- Data backup and recovery is possible.
- High data security
Disadvantages of Client-server network:
- Expensive.
- Difficult to troubleshoot and maintain.
- Server failure leads to whole network failure.
- Difficult to install and required technical manpower.
On the basis of Geographical Area:
On the basis of geographical area computer network is further classified into three categories, LAN, MAN and WAN.
Local Area Network (LAN):
A LAN is a system of interlinked personal computer in a localized area, typically less than 1km across. LANs normally
operate within a compact area such as an office building or a campus owned by the using organization. The configuration of LAN can be a star, a ring or simple devices attached along a length of cable. In LAN, transmission channels used are coaxial or fiber optic cable and special interface units rather than telephone lines and modems.
Ethernet, developed by Xerox Corporation, is a famous example of LAN. Omininet developed by Corvus System is another example of LAN.
Advantages of LAN:
- It provides cheaper and reliable communication medium.
- High data transmission rate is possible.
- Easy to add new computer to network.
- Failure of one computer in the network does not affect the functioning for the other computers.
Disadvantages of LAN:
- Installation cost is high.
- User authority and identification is poor.
- Occupies limited geographical area.
Metropolitan Area Network (MAN):
A network which is designed to extend over an entire city is known as MAN. A MAN can include one or more LANs. A
MAN is larger than LANs and smaller than WAN. It extended around 100 km or less. It is owned by be either public or private owned companies. In addition, they may somewhat slower data communication rates than do LANs, partly because of their reliance on unbounded media over great distance. Cable Television, cable internet, microwave links in banks, cooperates offices with in different cities etc.
Advantages of MAN:
- Nodes are located in wider areas (generally connects the cities)
- Owned by the big organization. (Government, Semi-government or big private organization)
- It enables you to connect many fast LANs together.
- It offers centralized management of data
- It provides high security.
Disadvantages of MAN:
- Data rate is slow as compared to LAN
- Error rate is high as compared to LAN
- Expensive.
- Difficult to maintenance.
Wide Area Network (WAN):
A network that connects LAN over a potentially large geographic distance is known as WAN. WAN is a large network and also called network of network. The distance between computers connected to WAN is larger. Therefore the transmission medium used is normally telephone line, microwaves and satellite links. A WAN provides long distance transmission of data, voice, image and video information over a large geographical area that may comprises a country, a continent or even the whole world. The best example of WAN is an Internet.
Advantages of WAN:
- It covers large geographical area.
- It connects different types of network together.
- WAN has made life and communication very easy.
- It can support large number of hosts.
- It is owned by the multiple organizations.
Disadvantages of WAN:
- Lower data transfer rate.
- Set-up costs are higher.
- Difficult to maintenance.
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