Communication Systems and Computer Networks PDF

Communication Systems and Computer Networks (1404703) Prepared by: Prof. Shawkat K. Guirguis Professor of Computer Science & Informatics Part 7 2024-11-1...

Communication Systems and Computer Networks (1404703) Prepared by: Prof. Shawkat K. Guirguis Professor of Computer Science & Informatics Part 7 2024-11-11 (c) Prof.Shawkat K. Guirguis 1  NETWORK STANDARDIZATION Who’s Who in the Telecommunications World Who’s Who in the International Standards World Who’s Who in the Internet Standards World 2024-11-11 (c) Prof. Shawkat K. Guirguis 2  NETWORK STANDARDIZATION (cont.) Standards fall into two categories: de facto and de jure. De facto (Latin for ‘‘from the fact’’) standards are those that have just happened, without any formal plan. The IBM PC and its successors are de facto standards for small-office and home computers because dozens of manufacturers chose to copy IBM’s machines very closely. Similarly, UNIX is the de facto standard for operating systems in university computer science departments. De jure (Latin for ‘‘by law’’) standards, in contrast, are formal, legal standards adopted by some authorized standardization body. 2024-11-11 (c) Prof. Shawkat K. Guirguis 3  NETWORK STANDARDIZATION (cont.) International standardization authorities are generally divided into two classes: a. Those established by treaty among national governments, and b. those comprising voluntary, Non-treaty organizations. 2024-11-11 (c) Prof. Shawkat K. Guirguis 4  1 Who's Who in the Telecommunications World The legal status of the world’s telephone companies varies considerably from country to country. At one extreme is the United States, which has 1500 separate, privately owned telephone companies. Before it was broken up in 1984, AT&T, at that time the world’s largest corporation, completely dominated the scene. At the other extreme are countries in which the national government has a complete monopoly on all communication, including the mail, telegraph, telephone, and often, radio and television. Most of the world falls in this category. 2024-11-11 (c) Prof. Shawkat K. Guirguis 5  1 Who's Who in the Telecommunications World (cont.) In some cases the telecommunication authority is a nationalized company, and in others it is simply a branch of the government, usually known as the PTT (Post, Telegraph & Telephone administration). Worldwide, the trend is toward liberalization and competition and away from government monopoly. Most European countries have now (partially) privatized their PTTs, but elsewhere the process is still slowly gaining steam. 2024-11-11 (c) Prof. Shawkat K. Guirguis 6  1 Who's Who in the Telecommunications World (cont.) With all these different suppliers of services, there is clearly a need to provide compatibility on a worldwide scale to ensure that people (and computers) in one country can call their counterparts in another one. Actually, this need has existed for a long time. In 1865, representatives from many European governments met to form the predecessor to today’s ITU (International Telecommunication Union). Its job was standardizing international telecommunications, which in those days meant telegraphy. Even then it was clear that if half the countries used Morse code and the other half used some other code, there was going to be a problem. When the telephone was put into international service, ITU took over the job of standardizing telephony as well. 2024-11-11 (c) Prof. Shawkat K. Guirguis 7  EGYPT Joined ITU 1876 First gathering in Egypt 1938 International Radiocommunication Conference (Cairo, 1938) 1st February - 8 April 1938 - Cairo, Egypt Second gathering in Egypt 2019!! World Radio-communication Conference 2019 (WRC-19) 28th October to 22nd November 2019, Sharm El-Sheikh, Egypt. 2024-11-11 (c) Prof. Shawkat K. Guirguis 8  In 1947, ITU became an agency of the United Nations. ITU has three main sectors: 1. Radio-communications Sector (ITU-R). 2. Telecommunications Standardization Sector (ITU-T). 3. Development Sector (ITU-D). ITU-R is concerned with allocating radio frequencies worldwide to the competing interest groups. ITU-T is concerned with telephone and data communication systems. 2024-11-11 (c) Prof. Shawkat K. Guirguis 9  1 Who's Who in the Telecommunications World (cont.) From 1956 to 1993, ITU-T was known as CCITT, an acronym for its French name: Comite´ Consultatif International Te´le´graphique et Te´le´phonique. On March 1, 1993, CCITT was reorganized to make it less bureaucratic and renamed to reflect its new role. Both ITU-T and CCITT issued recommendations in the area of telephone and data communications. One still frequently runs into CCITT recommendations, such as CCITT X.25, although since 1993 recommendations bear the ITU-T label. 2024-11-11 (c) Prof. Shawkat K. Guirguis 10 ITU-T has four classes of members: National governments. Sector members. Associate members. Regulatory agencies. 2024-11-11 (c) Prof. Shawkat K. Guirguis 11  1 Who's Who in the Telecommunications World (cont.) ITU-T has about 200 governmental members, including almost every member of the United Nations. Since the United States does not have a PTT, somebody else had to represent it in ITU-T. This task fell to the State Department, probably on the grounds that ITU-T had to do with foreign countries, the State Department’s specialty. There are approximately 500 sector members, including telephone companies (e.g., AT&T, Vodafone, WorldCom), telecom equipment manufacturers (e.g., Cisco, Nokia, Nortel), computer vendors (e.g., Compaq, Sun, Toshiba), chip manufacturers (e.g., Intel, Motorola, TI), media companies (e.g., AOL Time Warner, CBS, Sony), and other interested companies (e.g., Boeing, Samsung, Xerox). Various nonprofit scientific organizations and industry consortia are also sector members (e.g., IATA). Associate members are smaller organizations that are interested in a particular Study Group. 2024-11-11 (c) Prof. Shawkat K. Guirguis 12  1 Who's Who in the Telecommunications World (cont.) Regulatory agencies are the folks who watch over the telecom business, such as the U.S. Federal Communications Commission. ITU-T’s task is to make technical recommendations about telephone, telegraph, and data communication interfaces. These often become internationally recognized standards, for example, V.24 (also known as EIA RS-232 in the United States), which specifies the placement and meaning of the various pins on the connector used by most asynchronous terminals and external modems. 2024-11-11 (c) Prof. Shawkat K. Guirguis 13  1 Who's Who in the Telecommunications World (cont.) It should be noted that ITU-T recommendations are technically only suggestions that governments can adopt or ignore, as they wish In practice, a country that wishes to adopt a telephone standard different from that used by the rest of the world is free to do so, but at the price of cutting itself off from everyone else. The real work of ITU-T is done in its 14 Study Groups, often as large as 400 people. 2024-11-11 (c) Prof. Shawkat K. Guirguis 14  1 Who's Who in the Telecommunications World (cont.) There are currently several Study Groups, covering topics ranging from telephone billing to multimedia services. In order to make it possible to get anything at all done, the Study Groups are divided into Working Parties, which are in turn divided into Expert Teams, which are in turn divided into ad hoc groups. ITU-T actually gets things done. Since its inception, it has produced thousands of recommendations occupying many thousands of pages. Many of these are widely used in practice. For example, the popular V.90 56-kbps modem standard is an ITU recommendation. 2024-11-11 (c) Prof. Shawkat K. Guirguis 15  2 Who's Who in the International Standards World International standards are produced and published by ISO (International Standards Organization), a voluntary non-treaty organization founded in 1946. Its members are the national standards organizations of the member countries. These members include ANSI (U.S.), BSI (Great Britain), AFNOR (France), DIN (Germany), and many others. ISO issues standards on a truly vast number of subjects, ranging from nuts and bolts (literally) to telephone pole coatings [not to mention cocoa beans (ISO 2451), fishing nets (ISO 1530), and quite a few other subjects one might not think were subject to standardization]. Over 13,000 and more standards have been issued, including the OSI standards. 2024-11-11 (c) Prof. Shawkat K. Guirguis 16  2 Who's Who in the International Standards World (cont.) ISO has almost 200 Technical Committees, numbered in the order of their creation, each dealing with a specific subject. TC1 deals with the nuts and bolts (standardizing screw thread pitches). TC97 deals with computers and information processing. Each TC has subcommittees (SCs) divided into working groups (WGs). The real work is done largely in the WGs by thousands of volunteers worldwide. Many of these ‘‘volunteers’’ are assigned to work on ISO matters by their employers, whose products are being standardized. Others are government officials keen on having their country’s way of doing things become the international standard. 2024-11-11 (c) Prof. Shawkat K. Guirguis 17  2 Who's Who in the International Standards World (cont.) Academic experts also are active in many of the WGs. On issues of telecommunication standards, ISO and ITU-T often cooperate (ISO is a member of ITU-T) to avoid the irony of two official and mutually incompatible international standards. The U.S. representative in ISO is ANSI (American National Standards Institute), which despite its name, is a private, nongovernmental, nonprofit organization. Its members are manufacturers, common carriers, and other interested parties. ANSI standards are frequently adopted by ISO as international standards. 2024-11-11 (c) Prof. Shawkat K. Guirguis 18  2 Who's Who in the International Standards World (cont.) The procedure used by ISO for adopting standards has been designed to achieve as broad a consensus as possible. The process begins when one of the national standards organizations feels the need for an international standard in some area. A working group is then formed to come up with a CD (Committee Draft). The CD is then circulated to all the member bodies, which get 6 months to criticize it. If a substantial majority approves, a revised document, called a DIS (Draft International Standard) is produced and circulated for comments and voting. Based on the results of this round, the final text of the IS (International Standard) is prepared, approved, and published. In areas of great controversy, a CD or DIS may have to go through several versions before acquiring enough votes, and the whole process can take years. 2024-11-11 (c) Prof. Shawkat K. Guirguis 19  2 Who's Who in the International Standards World (cont.) NIST (National Institute of Standards and Technology) is part of the U.S. Department of Commerce. It used to be the National Bureau of Standards. It issues standards that are mandatory for purchases made by the U.S. Government, except for those of the Department of Defense, which has its own standards. 2024-11-11 (c) Prof. Shawkat K. Guirguis 20  2 Who's Who in the International Standards World (cont.) IEEE (Institute of Electrical and Electronics Engineers), the largest professional organization in the world. In addition to publishing scores of journals and running hundreds of conferences each year, IEEE has a standardization group that develops standards in the area of electrical engineering and computing. IEEE’s 802 committee has standardized many kinds of LANs., which are listed in next figure 2024-11-11 (c) Prof. Shawkat K. Guirguis 21  IEEE 802 Standards The 802 working groups. The important ones are marked with *. The ones marked with  are hibernating. The one marked with † gave up. 2024-11-11 (c) Prof. Shawkat K. Guirguis 22  3 Who's Who in the Internet Standards World The worldwide Internet has its own standardization mechanisms, very different from those of ITU-T and ISO. The difference can be crudely summed up by saying that the people who come to ITU or ISO standardization meetings wear suits. The people who come to Internet standardization meetings wear jeans (except when they meet in San Diego, when they wear shorts and T-shirts). ITU-T and ISO meetings are populated by corporate officials and government civil servants for whom standardization is their job. They regard standardization as a Good Thing and devote their lives to it. Internet people, on the other hand, prefer anarchy as a matter of principle. 2024-11-11 (c) Prof. Shawkat K. Guirguis 23  3 Who's Who in the Internet Standards World (cont.) When the ARPANET was set up, DoD created an informal committee to oversee it. In 1983, the committee was renamed the IAB (Internet Activities Board) and was given a slighter broader mission, namely, to keep the researchers involved with the ARPANET The meaning of the acronym ‘‘IAB’’ was later changed to Internet Architecture Board. Each of the approximately ten members of the IAB headed a task force on some issue of importance. The IAB met several times a year to discuss results and to give feedback to the DoD. 2024-11-11 (c) Prof. Shawkat K. Guirguis 24  3 Who's Who in the Internet Standards World (cont.) When a standard was needed (e.g., a new routing algorithm), the IAB members would prepare it out and then announce the change so the graduate students who were the heart of the software effort could implement it. Communication was done by a series of technical reports called RFCs (Request For Comments). RFCs are stored on-line and can be fetched by anyone interested in them from www.ietf.org/rfc. They are numbered in chronological order of creation. Over 8000 now exist. 2024-11-11 (c) Prof. Shawkat K. Guirguis 25  3 Who's Who in the Internet Standards World (cont.) By 1989, the Internet had grown so large that this highly informal style no longer worked. Many vendors by then offered TCP/IP products and did not want to change them just because ten researchers had thought of a better idea. In the summer of 1989, the IAB was reorganized again. The researchers were moved to the IRTF (Internet Research Task Force), which was made subsidiary to IAB, along with the IETF (Internet Engineering Task Force). 2024-11-11 (c) Prof. Shawkat K. Guirguis 26  3 Who's Who in the Internet Standards World (cont.) The IAB was repopulated with people representing a broader range of organizations than just the research community. It was initially a self- perpetuating group, with members serving for a 2-year term and new members being appointed by the old ones. Later, the Internet Society was created, populated by people interested in the Internet. The Internet Society is thus in a sense comparable to ACM or IEEE. It is governed by elected trustees who appoint the IAB members. The idea of this split was to have the IRTF concentrate on long-term research while the IETF dealt with short-term engineering issues. The IETF was divided up into working groups, each with a specific problem to solve. Eventually, so many working groups were formed (more than 70). 2024-11-11 (c) Prof. Shawkat K. Guirguis 27  3 Who's Who in the Internet Standards World (cont.) In addition, a more formal standardization process was adopted, patterned after ISOs. To become a Proposed Standard, the basic idea must be completely explained in an RFC and have sufficient interest in the community to warrant consideration. To advance to the Draft Standard stage, a working implementation must have been rigorously tested by at least two independent sites for at least 4 months. If the IAB is convinced that the idea is sound and the software works, it can declare the RFC to be an Internet Standard. Some Internet Standards have become DoD standards (MIL- STD), making them mandatory for DoD suppliers. 2024-11-11 (c) Prof. Shawkat K. Guirguis 28  3 Who's Who in the Internet Standards World (cont.) BUT the story is still progressing and has many things to come!!! 2024-11-11 (c) Prof. Shawkat K. Guirguis 29