Telecomunication System

a. Ethernet

Ethernet is a networking technology developed in the early 1970s and governed by the IEEE 802.3 specification. Ethernet provides access to the networking using Carrier Sense Multiple Access with Collision Detection (CSMA/CD). Ethernet remains the most popular type of networking technology in use today. The main advantage of Ethernet is that it is one of the cheapest network architectures to implement. Network interface cards, cabling, and hubs are fairly inexpensive when compared to the hardware required for other architectures such as token ring. A major disadvantage of Ethernet relates to collisions on the network. The more collisions, the slower the network will run, and excessive collisions can even bring down the network.

b. Token Ring

Token ring is a network architecture developed by IBM that is physically wired as a start but that uses token passing in a logical ring topology. Token Ring's advantages include reliability and ease of maintenance. It uses a star-wired ring topology in which all computers are directly wired to a MAU. The MAU allows malfunctioning computers to be disconnected from the network. This overcomes one disadvantage of token-passing, which is that one malfunctioning computer can bring down the network, since all computers are actively passing signals around the ring.

c. FDDI

Fiber Distributed Data Interface (FDDI) is an architecture that provides high-speed network backbones that can be used to connect and extend the range of LANs. FDDI uses fiber-optic cable and is wired in a ring topology. FDDI uses token passing as its media-access method and can operate high speeds. FDDI is a fast, reliable standard. The dual, counter-rotating ring topology increases the network's reliability by keeping it functioning even if a cable is damaged. A major advantage of FDDI is speed. It operates over fiber optic cable at 100 Mbps. Optical cable is not bothered by electrical noise and has a higher transfer rate then wires carrying electronic signals. FDDI's main disadvantages are availability and price. Because FDDI is not useful for transmitting large graphic and sound files (such as video), it is being replaced by Gigabit Ethernet. FDDI adapter cards and fiber-optic cable are both expensive compared to other technologies offering the same speed. Fiber-optic cable installation

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