The Communication occurs between entities in different systems. An entity is anything capable of sending or receiving information. But two entities cannot just send bit streams to each other and expect to be understood. For communication to occur the entities must agree on a protocol. The key elements of a protocol are syntax, semantics and timing.
Syntax : Syntax refers to the structure or format of the data, meaning the order in which they are presented. For example , a simple protocol might expect the first eight bits of data to be the address of the sender , the second eight bits to be the address of receiver and rest of the stream to be the message itself.
Semantics : Semantics refers to the meaning of each section of bits. How is a particular pattern to be interpreted and what action is to be taken based on that information.
Timing : Timing refers to two characteristics. When data should be sent and how fast it can be sent. For example , if a sender produces data at 100 Mbps but the receiver can process data at only 1 Mbps, the transmission will overload and receiver and data will be largely lost.
Standards are essential in creating and maintaining an open and competitive market fro equipment manufacturers and in guaranteeing national and international operational ability of data and telecommunication technology and processes. They provide guidelines to manufacturers, vendors, government agencies and other service providers to ensure the king of interconnectivity necessary in today’s marketplace and in international communications.
Data communications standards fall into two categories
1. de facto ( by fact)
2. de jure ( by law)
De jure standards are those that have been legislated by an officially recognized body.
De facto standards are often established originally by manufacturers seeking the functionality of a new product or technology.
Standards are developed by cooperation among standard creation committees forums and government regulatory agencies.
i) The International Standards Organization (ISO)
ii) The International Telecommunication Union (ITU-T)
iii) ANSI (American National Standards Institute)
iv) The Institute of Electrical and Electronics Engineer (IEEE)
v) The Electronic Industries Association (EIA)
The ISO is an organization dedicated to worldwide agreement on international standards in variety of fields. ITU-T is an international standards organization related to the United Nations that develops standards for telecommunications. Two popular standards developed by ITU-T are the V series and X series. ANSI , a nonprofit organization is the United States, voting representative to both the ISO and ITU-T. The IEEE is the largest national professional group involved in developing standards for computing , communication, electrical engineering and electronics. It sponsored an important standard for Local Area Network (LAN) called project 802. EIA is an association of electronics manufacturers in the United States. It is responsible for developing the EIA-232-D and EIA-530 standards.