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DATA COMMUNICATIONS AND NETWORKING
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PROTOCOLS AND STANDARDS
In this section, we define two widely used terms: protocols and standards. First, we
define protocol, which is synonymous with rule. Then we discuss standards, which are
agreed-upon rules.
Protocols
In computer networks, communication occurs between entities in different systems. An
entity is anything capable of sending or receiving information. However, two entities cannot
simply send bit streams to each other and expect to be understood. For communication
to occur, the entities must agree on a protocol. A protocol is a set of rules that govern data
communications. A protocol defines what is communicated, how it is communicated, and
when it is communicated. The key elements of a protocol are syntax, semantics, and timing.
o Syntax. The term 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 8 bits of data to be the address of the sender, the second 8 bits to be the address
of the receiver, and the rest of the stream to be the message itself.
o Semantics. The word 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 interpretation? For example, does an address identify the route to be taken
or the final destination of the message?
o Timing. The term timing refers to two characteristics: when data should be sent
and how fast they 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 the
receiver and some data will be lost.
Standards
Standards are essential in creating and maintaining an open and competitive market for
equipment manufacturers and in guaranteeing national and international interoperability
of data and telecommunications technology and processes. Standards provide guidelines
INTRODUCTION
to manufacturers, vendors, government agencies, and other service providers to ensure
the kind of interconnectivity necessary in today's marketplace and in international communications.
Data communication standards fall into two categories: de facto (meaning
"by fact" or "by convention") and de jure (meaning "by law" or "by regulation").
o De facto. Standards that have not been approved by an organized body but have
been adopted as standards through widespread use are de facto standards. De facto
standards are often established originally by manufacturers who seek to define the
functionality of a new product or technology.
o De jure. Those standards that have been legislated by an officially recognized body
are de jure standards.
Standards Organizations
Standards are developed through the cooperation of standards creation committees,
forums, and government regulatory agencies.
Standards Creation Committees
While many organizations are dedicated to the establishment of standards, data telecommunications
in North America rely primarily on those published by the following:
o International Organization for Standardization (ISO). The ISO is a multinational
body whose membership is drawn mainly from the standards creation committees
of various governments throughout the world. The ISO is active in developing
cooperation in the realms of scientific, technological, and economic activity.
o International Telecommunication Union-Telecommunication Standards
Sector (ITU-T). By the early 1970s, a number of countries were defining national
standards for telecommunications, but there was still little international compatibility.
The United Nations responded by forming, as part of its International
Telecommunication Union (ITU), a committee, the Consultative Committee
for International Telegraphy and Telephony (CCITT). This committee was
devoted to the research and establishment of standards for telecommunications in
general and for phone and data systems in particular. On March 1, 1993, the name
of this committee was changed to the International Telecommunication UnionTelecommunication
Standards Sector (ITU-T).
o American National Standards Institute (ANSI). Despite its name, the American
National Standards Institute is a completely private, nonprofit corporation not affiliated
with the U.S. federal government. However, all ANSI activities are undertaken
with the welfare of the United States and its citizens occupying primary importance.
o Institute of Electrical and Electronics Engineers (IEEE). The Institute of
Electrical and Electronics Engineers is the largest professional engineering society in
the world. International in scope, it aims to advance theory, creativity, and product
quality in the fields of electrical engineering, electronics, and radio as well as in all
related branches of engineering. As one of its goals, the IEEE oversees the development
and adoption of international standards for computing and communications.
o Electronic Industries Association (EIA). Aligned with ANSI, the Electronic
Industries Association is a nonprofit organization devoted to the promotion of
SECTION 1.5 RECOMMENDED READING 21
electronics manufacturing concerns. Its activities include public awareness education
and lobbying efforts in addition to standards development. In the field of information
technology, the EIA has made significant contributions by defining physical connection
interfaces and electronic signaling specifications for data communication.
Forums
Telecommunications technology development is moving faster than the ability of standards
committees to ratify standards. Standards committees are procedural bodies and
by nature slow-moving. To accommodate the need for working models and agreements
and to facilitate the standardization process, many special-interest groups have developed
forums made up of representatives from interested corporations. The forums
work with universities and users to test, evaluate, and standardize new technologies. By
concentrating their efforts on a particular technology, the forums are able to speed
acceptance and use of those technologies in the telecommunications community. The
forums present their conclusions to the standards bodies.
Regulatory Agencies
All communications technology is subject to regulation by government agencies such
as the Federal Communications Commission (FCC) in the United States. The purpose
of these agencies is to protect the public interest by regulating radio, television,
and wire/cable communications. The FCC has authority over interstate and international
commerce as it relates to communications.
Internet Standards
An Internet standard is a thoroughly tested specification that is useful to and adhered
to by those who work with the Internet. It is a formalized regulation that must be followed.
There is a strict procedure by which a specification attains Internet standard
status. A specification begins as an Internet draft. An Internet draft is a working document
(a work in progress) with no official status and a 6-month lifetime. Upon recommendation
from the Internet authorities, a draft may be published as a Request for
Comment (RFC). Each RFC is edited, assigned a number, and made available to all
interested parties. RFCs go through maturity levels and are categorized according to
their requirement level.
RECOMMENDED READING
For more details about subjects discussed in this chapter, we recommend the following
books and sites. The items enclosed in brackets [...] refer to the reference list at the end
of the book.
Books
The introductory materials covered in this chapter can be found in [Sta04] and [PD03].
[Tan03] discusses standardization in Section 1.6.
INTRODUCTION
The following sites are related to topics discussed in this chapter.
o www.acmsigcomm/sos.html This site gives the status of varililus networking
standards.
o www.ietf The Internet Engineering Task Force (IETF) home page.
RFCs
The following site lists all RFCs, including those related to IP and TCP. In future chapters
we cite the RFCs pertinent to the chapter material.