8 megabits with 30 channels for voice, is equal to 1,000,000,000,000,000,000 bytes data, or video, plus one channel for signaling or 1 billion gigabytes. A byte is equal to 8 and one for diagnostics. bits, or one character. Glossary FDDI (Fiber-Distributed Data tower and a dish on a business or residential Interface) customer's building. It is also used to connect An ANSI-defined protocol in which comput- two buildings together as a lower-cost option ers communicate at 100Mbps over fiber-optic than running cabling. Used most often in cabling. FDDI can be used on backbones that rural or hard-to-cable areas. connect LAN segments together. It is not widely used. fractional T1 A less expensive T1 access scheme in which fiber-optic cable the customer pays for use of just a fraction A type of cable that is made from glass of the 24-channel capacity of T1 lines. The strands rather than copper wire. The key most common capacities are 2 channels = advantage of fiber-optic cabling is that it is 128Kbps, 4 channels = 256Kbps, and 6 chan- nonelectric. Thus, it is immune from electri- nels = 384Kbps. cal interference and interference from other cables within the same conduit. Fiber-optic fractional T3 cabling can be used for higher-speed trans- A less expensive T3 access scheme in which missions than twisted-pair copper cabling. the customer pays for a fraction of the 672-channel capacity of T3 lines. For exam- Fibre Channel protocol ple, it might have the capacity of six T1s or Used in storage area networks and data cen- 144 channels. Fractional T3s are cheaper ters for gigabit-speed, highly reliable, short- than a full T3 line. distance access to devices such as disks, graphics equipment, video input/output frame relay network devices, and storage devices that hold mas- An older public virtual data network com- sive amounts of data. monly used for LAN-to-LAN communica- tions and Internet access. Customers, usually firewall small and midsize organizations, connect to Software and hardware that prevents unau- frame relay serv