TAILIEUCHUNG - Lecture Data communications and networking: Chapter 8 - Behrouz A. Forouzan

Although the previous chapters in this part are issues related to the physical layer or transmission media, Chapter 8 discusses switching, a topic that can be related to several layers. We have included this topic in this part of the book to avoid repeating the discussion for each layer. | Chapter 8 Switching Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 8. Figure Switched network 8. Figure Taxonomy of switched networks 8. 8-1 CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches connected by physical links. A connection between two stations is a dedicated path made of one or more links. However, each connection uses only one dedicated channel on each link. Each link is normally divided into n channels by using FDM or TDM. Three Phases Efficiency Delay Circuit-Switched Technology in Telephone Networks Topics discussed in this section: 8. A circuit-switched network is made of a set of switches connected by physical links, in which each link is divided into n channels. Note 8. Figure A trivial circuit-switched network 8. In circuit switching, the resources need to be reserved during the setup phase; the resources remain dedicated for the entire duration of data transfer until the teardown phase. Note 8. As a trivial example, let us use a circuit-switched network to connect eight telephones in a small area. Communication is through 4-kHz voice channels. We assume that each link uses FDM to connect a maximum of two voice channels. The bandwidth of each link is then 8 kHz. Figure shows the situation. Telephone 1 is connected to telephone 7; 2 to 5; 3 to 8; and 4 to 6. Of course the situation may change when new connections are made. The switch controls the connections. Example 8. Figure Circuit-switched network used in Example 8. As another example, consider a circuit-switched network that connects computers in two remote offices of a private company. The offices are connected using a T-1 line leased from a communication service provider. There are two 4 × 8 (4 inputs and 8 outputs) switches in this network. For each switch, four output ports are folded into the input ports to allow communication between computers .

• Quản trị mạng
• Data communications
• Lecture Data communications
• Physical layer
• Data link layer
• Circuit switched networks
• Datagram networks
• Business data communications
• Network criteria
• Data communications system
• Data communications networks
• Media access control
• Network models
• Network standards
• Application layer
• Application architectures
• Digital transmission
• Network and transport layers
• Transport layers
• Local area networks
• Traditional ethernet
• Wireless local area networks
• Wireless LANs
• Backbone networks
• Backbone network architectures
• Wide area networks
• Network security
• Risk assessment
• Network design
• Traditional network design
• Network management
• Configuration management