Telecommunication Essay Research Paper Telecommunication1 IntroductionComputer and — страница 5

the coaxial cable, has a large diameter, and can only span short distances. These cables use the IBM data connector. The fiber optic cable is the fastest possible type of data transfer, costs astronomical amounts of money, has a tiny diameter, and can span very long distances. This cable uses the ST fiber optic connector. Wiring hubs are used as central points for the cables from the network interface cards. 5.5. Loves Me, Loves Me Not, Server Based, Peer To Peer… There are two general types of LANs. The Server-based networks rely on one major server to store data, offer access to perhiperals, handle the printing and accomplish all the work associated with network management. The Server- based networks have a high start up cost, but offer high security as well as ease of

operation. These networks become more economical as more computers are added to the network. In Peer to peer networks the network responsibilities are divided among many computers. Some act as file servers, others as print servers, some as CD-ROM servers, tape drive servers, etc. The Startup cost of these networks is much cheaper, but when more computers are added to the network, some of the servers may not be able to handle the extra activity. 5. Links Between LANs 5.1. She Just Won’t Send Sysop! Most networks have very short information transfer ranges. But, in an ever shrinking world the need for links between LANs has never been higher. This section will explain the components and information needed to link LANs. When an electric current travels over a long length, it’s

charge decreases, and it is susceptible to electromagnetic interference. To combat the length problem a component has been devised. A repeater is a little box that is inserted between a cable. It’s primary function is to amplify the weakening pulse and send it on it’s way. Bridges are used to analyze the station address of each Ethernet packet and determine the destination of the message. The Routers strip the outer Ethernet packets of a data packet in order to get the data. This data is sent to other routers in other places of the world and then repackaged by those routers. The removal of the excess data packets by the routers decreases the time required to transfer that data. If networks use the same addressing protocol, bridges can be used to link them, however, if they

use different addressing protocols, only routers may be used. During these times MANs (Metropolitan Area Networks) are in use and development today. These use routers that are connected preferably via a fiber optic cable, to create one large network. 5.2. Pluto Calling Earth! Any networks larger than 1000m typically rely on telephone digital lines for data transfer. These networks are called Circuit Switched Digital Networks . Circuit Switched Digital Networks utilize a switching matrix at the central office of a telephone company that connects local calls to long distance services. The Telephone companies now offer dial up circuits with signaling rates of 56, 64, and 384 kilobits per second as well as 1.544 megabits per second. Another type of LAN to LAN connections are packet

switching networks. These are services that a network router calls up on a digital line. They consist of a group of packet switches that are connected via intraswitch trunks (usually fiber optic) that relay addressed packets of information between them. Once the packet reaches the destination packet switch, it sends it via another digital connection to the receiving router.