For a local area network (LAN), CDDI (Copper Distributed Data Interface) is a standard for data transmission based on FDDI (Fiber Distributed Data Interface) that uses shielded twisted-pair (STP) or unshielded twisted pair (UTP) copper wire instead of fiber optic lines. CDDI supports a dual-ring capacity of 200 Mbps. CDDI's maximum distance is up to 200 meters, which is much shorter than FDDI. CDDI is defined by the American National Standards Committee X3-T9.5 and conforms to the Open Systems Interconnection (OSI) model of functional layering. CDDI is officially named the Twisted-Pair Physical Medium Dependent (TP-PMD) standard and is also referred to as Twisted Pair Distributed Data Interface (TP-DDI).
Fiber distributed data interface (FDDI), which is an optical data communication standard used for long distance networks provides communication with fiber optic lines up to 200 kilometers at a speed of 100 megabit per second (Mbps).It should be noted that relatively recently, a related copper specification, called Copper Distributed Data Interface (CDDI) has emerged to provide 100-Mbps service over copper. CDDI is the implementation of FDDI protocols over twisted-pair copper wire.FDDI uses a dual-ring architecture with traffic on each ring flowing in opposite directions (calledcounter-rotating). The dual-rings consist of a primary and a secondary ring. During normal operation, the primary ring is used for data transmission, and the secondary ring remains idle and available for backup. The primary purpose of the dual rings, as will be discussed in detail later in this chapter, is to provide superior reliability and robustness. FDDI was later extended to FDDI-2 for long distance voice and multimedia communication.
FDDI Advantages: ~Supports real time allocation of network bandwidth. ~Supports a lot of different types of network traffic. ~Is fault-tolerant because it uses dual fiber cables. If one cable fails FDDI moves the data to the other dual cable. FDDI Disadvantages: ~It's expensive ~There is always a chance of multiple ring failures and as the ring grows, that chance increases. ~It's not used frequently due to cost, companies prefer to use copper (CDDI) if they are taking the ring approach.
standard for data transmission in a local area network that can extend in range up to 200 kilometers (124 miles). Although FDDI logical topology is a token ring network, it does not use the IEEE 802.5 token ring protocol as its basis; instead, its protocol is derived from the IEEE 802.4 token bus timed token protocol. In addition to covering large geographical areas, FDDI local area networks can support thousands of users. As a standard underlying medium it uses optical fiber, although it can use copper cable, in which case it may be refer to as CDDI. FDDI uses a dual-attached, counter-rotating token ring topology.FDDI was considered an attractive campus backbone technology in the early to mid 1990s, but FDDI has since been effectively obsoleted by fast Ethernet and, since 1998, by Gigabit Ethernet due to their speed, lower cost, and ubiquity.FDDI, as a product of American National Standards Institute X3T9.5 (now X3T12), conforms to the Open Systems Interconnection (OSI) model of functional layering of LANs using other protocols. FDDI-II, a version of FDDI, adds the capability to add circuit-switched service to the network so that it can also handle voice and video signals. Work has started to connect FDDI networks to the developing Synchronous Optical Network SONET.A FDDI network contains two token rings, one for possible backup in case the primary ring fails. The primary ring offers up to 100 Mbit/s capacity. When a network has no requirement for the secondary ring to do backup, it can also carry data, extending capacity to 200 Mbit/s. The single ring can extend the maximum distance; a dual ring can extend 100 km (62 miles). FDDI has a larger maximum-frame size than standard 100 Mbit/s Ethernet, allowing better throughput.Designers normally construct FDDI rings in the form of a "dual ring of trees" (see network topology). A small number of devices (typically infrastructure devices such as routers and concentrators rather than host computers) connect to both rings - hence the term "dual-attached". Host computers then connect as single-attached devices to the routers or concentrators. The dual ring in its most degenerate form simply collapses into a single device. Typically, a computer-room contains the whole dual ring, although some implementations have deployed FDDI as a Metropolitan area network
the Application Software is a software that APPLIES to the real life application. For example: Microsoft Word is used to create documents similar to you create manually on paper. Accounting Softwares those are used for accounting which is simallarly done manually on Account Book. Thus, Application Software are easier to be understood by normal users because they directly deals with the normal real life applications. But the System Softwares are the softwares which deals with the system or hardware. For example: Disk Management Tools which are used to partition or format the disk. System Softwares are recommended to be used only by Advanced users who are having advance knowledge of the computer system.