Computer Networks are used for data communications
A computer network can be defined as a collection of nodes. A node can be any device capable of transmitting or
receiving data. The communicating nodes have to be connected by communication links.
A Compute network should ensure
reliability of the data communication process, should c
security of the data
performance by achieving higher throughput and smaller delay times
Categories of Network
Networks are categorized on the basis of their size. The three basic categories of computer networks are:
A.Local Area Networks (LAN) is usually limited to a few kilometers of area. It may be privately owned and could be a network inside an office on one of the floor of a building or a LAN could be a network consisting of the computers in a entire building.
B.Wide Area Network (WAN) is made of all the networks in a (geographically) large area. The network in the entire state of Maharashtra could be a WAN
C.Metropolitan Area Network (MAN) is of size between LAN & WAN. It is larger than LAN but smaller than WAN. It may comprise the entire network in a city like Mumbai.
- A Protocol is one of the components of a data communications system. Without protocol communication
cannot occur. The sending device cannot just send the data and expect the receiving device to receive and further interpret it correctly.
- When the sender sends a message it may consist of text, number, images, etc. which are converted into bits and
grouped into blocks to be transmitted and often certain additional information called control information is also added to help the receiver interpret the data.
- For successful communication to occur, the sender and receiver must agree upon certain rules called protocol.
A Protocol is defined as a set of rules that governs data communications.
- A protocol defines what is to be communicated, how it is to be communicated and when it is to be communicated.
Elements of a Protocol
There are three key elements of a protocol:
It means the structure or format of the data. It is the arrangement of data in a particular order.
It tells the meaning of each section of bits and indicates the interpretation of each section. It also tells what action/decision is to be taken based on the interpretation.
It tells the sender about the readiness of the receiver to receive the data It tells the sender at what rate the data should be sent to the receiver to avoid overwhelming the receiver.
STANDARDS IN NETWORKING
- Standards are necessary in networking to ensure interconnectivity and interoperability between various
networking hardware and software components. Without standards we would have proprietary products
creating isolated islands of users which cannot interconnect.
Concept of Standard
Standards provide guidelines to product manufacturers and vendors to ensure national and international
Data communications standards are classified into two categories
1. De facto Standard
- These are the standards that have been traditionallyused and mean by fact or by convention
- These standards are not approved by any organized body but are adopted by widespread use.
2. De jure standard
- It means by law or by regulation.
- These standards are legislated and approved by an body that is officially recognized.
Standard Organizations in field of Networking
Standards are created by standards creation committees, forums, and government regulatory agencies.
- Examples of Standard Creation Committees :
1. International Organization for Standardization(ISO)
2. International Telecommunications Union –Telecommunications Standard (ITU-T)
3. American National Standards Institute (ANSI)
4. Institute of Electrical & Electronics Engineers (IEEE)
5. Electronic Industries Associates (EIA)
- Examples of Forums
1. ATM Forum
2. MPLS Forum
3. Frame Relay Forum
- Examples of Regulatory Agencies:
1. Federal Communications Committee (FCC)