HOMEWORK WEEK 6
9.) Compare and contrast circuit-switched services, dedicated-circuit services, and packet-switched services. Circuit switched services are the oldest approach to MAN and WAN circuits. They began operating over the PSTN or the Public Switched Telephone Network that carriers like AT&T, and Bell South ran on. A simple telephone call is based off of this premise. Circuit switched services rely on cloud architecture. This means that the users must lease connection points into the common carrier network, and then a person/computer dials the phone number of the destination and provides a temporary circuit. The circuit becomes disconnected when the computers are done exchanging data(phone is hung up). The two basic types of switched Circuit Services we use are POTS and ISDN. POTS or Plain Old Telephone Service, is referred to as dial up you may be familiar with. ISDN is the Integrated Digital Services Network. It combines voice, video and data on the same digital circuit. (Fitzgerald, 297-298). Dedicated Circuit services allow you to lease circuits from those common carriers and then equipment is later installed to connect the computers and devices to the circuit. Equipment can include items such as multiplexers, a channel service unit or a data service unit. Connections that are made are point-to-point; mainly one building in one city to another building in that same city or a different one. The three basic architectures in these networks are ring, star and mesh; however they can be combined. One example of this is a distributed star architecture in which a series of star networks are connected by a ring/mesh architecture. Two types of dedicated circuit services used today are: T carrier services and synchronous optical network (SONET) services. Each of these has their own data link protocols. (Fitzgerald, 299-300). Packet Switched Services unlike circuit switched and dedicated circuit network s do not have to wait for the circuit is closed for...
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