信息通信Chapter 02.ppt

Chapter 2 Basic Concepts Two ways to share a link: Peer-to-peer (对等方式). The devices share the link equally. Primary-secondary (主从方式). Where one device controls traffic and the others must transmit through it. Ring and mesh topologies are more convenient for peer-to-peer transmission. Simplex transmission means that data flows in one direction only. Half-duplex transmission allows data to flow in both directions, but not at the same time. Full-duplex transmission allows data to flow in both directions at the same time. A network can be categorized as local area network (LAN), metropolitan area network (MAN), or a wide area network (WAN) A LAN is a data communication system within a building, plant, or campus, or between nearby buildings. * * Chapter 2 Basic Concepts 2.1 Line Configuration 线路配置 2.2 Topology 拓扑结构 2.3 Transmission Mode 传输模式 2.4 Categories of Networks 2.5 Internetworks 互联网络 2.6 Summary 2.1 Line Configuration Line configuration refers to the way two or more devices attach to a link (链路) . A link is the physical communication pathway that transfers data from one device to another. There are two possible line configurations: point–to–point and multipoint. (Fig2.1) Fig2.2 Point-to-point 2.1 Line Configuration 2.1.1 Point-to-point 点对点 This configuration provides a dedicated link(专用链路) between two devices. The dedicated link maybe wired or wireless. an actual wire-cable wireless-microwaves or satellite links 2.1.2 Multipoint 多点连接 (also called multidrop line configuration 多分支连接) means more than two specific devices share a single link. spatially shared: 空分共享 devices can use the link simultaneously time shared 时分共享 (temporally shared) devices must take turns 2.1 Line Configuration Fig2.3 Multipoint 2.2 Topology Topology defines the way a network is laid out, either physically or logically arrangement. 网络物理或逻辑的安排方式。 five basic topologies mesh