Data Communication Network:
Data communications are the exchange of data between two devices using one or multiple forms of transmission medium. That is, data communication is movement of data from one device or end-point to another device or end point through electrical or optical medium. Systems that facilitate this movement of data between devices or end-points are called data communication network. The devices which are in need to be a part of a data communication network made up of computer hardware and software.
Data communication networks collect data from devices such as microphone and let the data to be carried to the receiver or destination such as a micro-computer or minicomputer. However, it could be the opposite, that is data communication networks can also carry data from a micro-computer or minicomputer to a device such as printer. Data communications networks facilitate more efficient use of computers and improve the day-to-day control of a business by providing faster information flow. They also provide message transfer services to allow computer users to talk to one another via electronic mail, chat, and video streaming.
Components of a Data Communication Network
Following are the five components of a data communication network.
- Data
- Sender
- Receiver
- Transmission Medium
- Protocol
Data:
Communication of data means a message or data will be transmitted from one device and will be received in the destination or target device. Thus the first component in a data communication network is data or message to that needs to be delivered and received. Data or message can be of various forms such as text, audio, video, image or combinations of these forms etc.
Sender:
A data must has to be sent to a destination from a source. This source is called the sender. The device that sends the data to the destination or target is the Sender. It can be a computer, cell phone, video camera and so on.
Receiver:
The destination of a transmitted data is the receiver which will receive the data. The device that receives the data that was sent by the Sender is the Receiver. A receiver can again be a computer, cell phone, video camera and so on.
Transmission medium:
In data communication network, the transmission medium is the physical path for the data to travel to its destination after being sent by the Sender. Receiver receives the data at one end of this path and the sender sent from another end of the path. Transmission medium could be like twisted-pair cable, coaxial cable, fiber-optic cable etc.
Protocol:
A protocol is nothing but a set of rules that applies on the full data communication procedure. This is like an agreement between the two devices to successfully communicate with each other. For example, how the data will be sent, how the data will be traveling, how to ensure that full data has received, how to handle errors in transmission etc. Both devices follow the same set of rules or protocol so that they understand each other.
Goals of Networks
Computer Network means an interconnection of autonomous (standalone) computers for information exchange. The connecting media could be a copper wire, optical fiber, microwave or satellite.
Networking Elements – The computer network includes the following networking elements:
- At least two computers
- Transmission medium either wired or wireless
- Protocols or rules that govern the communication
- Network software such as Network Operating System Network Criteria:
The criteria that have to be met by a computer network are:
1. Performance – It is measured in terms of transit time and response time.
- Transit time is the time for a message to travel from one device to another
- Response time is the elapsed time between an inquiry and a response.
Performance is dependent on the following factors:
- The number of users
- Type of transmission medium
- Capability of connected network
- Efficiency of software
2. Reliability – It is measured in terms of
- Frequency of failure
- Recovery from failures
- Robustness during catastrophe
3. Security – It means protecting data from unauthorized access.
Goals of Computer Networks: The following are some important goals of computer networks:
- Resource Sharing –
Many organization has a substantial number of computers in operations, which are located apart. Ex. A group of office workers can share a common printer, fax, modem, scanner etc.
- High Reliability –
If there are alternate sources of supply, all files could be replicated on two or, machines. If one of them is not available, due to hardware failure, the other copies could be used.
- Inter-process Communication –
Network users, located geographically apart, may converse in an interactive session through the network. In order to permit this, the network must provide almost error-free communications.
- Flexible access –
Files can be accessed from any computer in the network. The project can be begun on one computer and finished on another.
Computer Networks: Business Applications
Following are some business applications of computer networks:
- Resource Sharing:
The goal is to make all programs, equipments(like printers etc), and especially data, available to anyone on the network without regard to the physical location of the resource and the user.
- Server-Client model:
One can imagine a company’s information system as consisting of one or more databases and some employees who need to access it remotely. In this model, the data is stored on powerful computers called Servers. Often these are centrally housed and maintained by a system administrator. In contrast, the employees have simple machines, called Clients, on their desks, using which they access remote data.
- Communication Medium:
A computer network can provide a powerful communication medium among employees. Virtually every company that has two or more computers now has e-mail (electronic mail), which employees generally use for a great deal of daily communication
4. eCommerce:
A goal that is starting to become more important in businesses is doing business with consumers over the Internet. Airlines, bookstores and music vendors have discovered that many customers like the convenience of shopping from home. This sector is expected to grow quickly in the future.
Computer Network Components
Computer networks components comprise both physical parts as well as the software required for installing computer networks, both at organizations and at home. The hardware components are the server, client, peer, transmission medium, and connecting devices. The software components are operating system and protocols. The following figure shows a network along with its components −
Hardware Components
- Servers −Servers are high-configuration computers that manage the resources of the network. The network operating system is typically installed in the server and so they give user accesses to the network resources. Servers can be of various kinds: file servers, database servers, print servers etc.
- Clients − Clients are computers that request and receive service from the servers to access and use the network resources.
- Peers − Peers are computers that provide as well as receive services from other peers in a workgroup network.
- Transmission Media − Transmission media are the channels through which data is transferred from one device to another in a network. Transmission media may be guided media like coaxial cable, fibre optic cables etc; or maybe unguided media like microwaves, infra-red waves etc.
- Connecting Devices − Connecting devices act as middleware between networks or computers, by binding the network media together. Some of the common connecting devices are:
- Routers
- Bridges
- Hubs
- Repeaters
- Gateways
- Switches
Software Components
- Networking Operating System − Network Operating Systems is typically installed in the server and facilitate workstations in a network to share files, database, applications, printers etc.
- Protocol Suite − A protocol is a rule or guideline followed by each computer for data communication. Protocol suite is a set of related protocols that are laid down for computer networks. The two popular protocol suites are − o a. OSI Model ( Open System Interconnections) o b. TCP / IP Model