Summary

Chapter 8: Fundamental Networks 33FDDIFDDI is a type of Token Ring network. The implementation and topology of FDDI differsfrom the IBM Token Ring LAN architecture. FDDI is often used to connect several buildingsin an office complex or on a university campus.FDDI runs on fiber-optic cable. FDDI combines high-speed performance with the advantagesof the token-passing ring topology. FDDI runs at 100 Mbps on a dual-ring topology.The outer ring is called the primary ring, and the inner ring is called the secondary ring.Normally, traffic flows on only the primary ring. If the primary ring fails, the data automaticallyflows onto the secondary ring in the opposite direction.An FDDI dual ring supports a maximum of 500 computers per ring. The total distance ofeach length of the cable ring is 62 miles (100 km). A repeater, which is a device that regeneratessignals, is required every 1.2 miles (2 km). In recent years, many Token Ring networkshave been replaced by faster Ethernet networks.Identify Standards OrganizationsSeveral worldwide standards organizations are responsible for setting networking standards.Manufacturers use standards as a basis for developing technology, especially communicationsand networking technologies. Standardizing technology ensures that the devices youuse are compatible with other devices using the same technology. Standards groups create,examine, and update standards. These standards are applied to the development of technologyto meet the demands for higher bandwidth, efficient communication, and reliable service.Here is a list of standards organizations:■■IEEE: The Institute of Electrical and Electronic Engineers is a nonprofit technical professionalassociation of more than 377,000 members in 150 countries. Founded in1884, the organization is composed of engineers, scientists, and students. Through itsmembers, the IEEE is a leading authority in technical areas ranging from computerengineering, biomedical technology, and telecommunications to electric power, aerospace,and consumer electronics.ISO: The International Organization for Standardization is an international organizationcomposed of national standards bodies from more than 140 countries. TheAmerican National Standards Institute (ANSI), for example, is a member of ISO. ISOis a nongovernment organization established to promote the development of standardizationand related activities. ISO’s work results in international agreements, which arepublished as International Standards.ISO has defined a number of important computer standards, the most significant ofwhich is perhaps the OSI model, a standardized architecture for designing networks.