Data Communications and Networking Forouzan Fourth Edition Chapter 12 Multiple Access 多路访问 12.1 CopyrightThe McGraw-Hill Companies,Inc.Permission required for reproduction or display
12.1 Chapter 12 Multiple Access 多路访问 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
Figure 12.1 Data link layer divided into two functionality-oriented sub 数据链路层分为两个功能子层： 数据链路控制子层和多路访问控制子层 Data link layer Data link control Multiple-access resolution 12.2
12.2 Figure 12.1 Data link layer divided into two functionality-oriented sublayers 数据链路层分为两个功能子层: 数据链路控制子层和多路访问控制子层
Figure 12.2 Taxonomy of multiple-access protocols discussed in this ch 多路访问控制协议的分类： 随机访问协议 受控访问控制协议 通道化协议 Multiple-access protocols Random access Controlled-access Channelization protocols protocols protocols ALOHA Reservation FDMA CSMA Polling TDMA CSMA/CD Token passing CDMA CSMA/CA 12.3
12.3 Figure 12.2 Taxonomy of multiple-access protocols discussed in this chapter 多路访问控制协议的分类： 随机访问协议 受控访问控制 协议 通道化协议
12-1 RANDOMACCESS 随机访问协议 In random access or contention methods,no station is superior to another station and none is assigned the control over another.No station permits,or does not permit,another station to send.At each instance,a station that has data to send uses a procedure defined by the protocol to make a decision on whether or not to send. 在随机访问或竞争访问方式中，没有一个站点是优于其它站点的， 也不能控制其它站点。没有站点有权力允许或不允许其它站点发 送或不发送数据。有数据要发送的站通过自身的协议决定发送还 是不发送数据。 Topics discussed in this section: ALOHA ALOHA协议 Carrier Sense Multiple Access 载波侦听多路访问协议CSMA Carrier Sense Multiple Access with Collision Detection带有冲突检测能力CSMA Carrier Sense Multiple Access with Collision Avoidance带冲突避免CSMA 12.4
12.4 12-1 RANDOM ACCESS 随机访问协议 In random access or contention methods, no station is superior to another station and none is assigned the control over another. No station permits, or does not permit, another station to send. At each instance, a station that has data to send uses a procedure defined by the protocol to make a decision on whether or not to send. 在随机访问或竞争访问方式中，没有一个站点是优于其它站点的， 也不能控制其它站点。没有站点有权力允许或不允许其它站点发 送或不发送数据。有数据要发送的站通过自身的协议决定发送还 是不发送数据。 ALOHA ALOHA协议 Carrier Sense Multiple Access 载波侦听多路访问协议 CSMA Carrier Sense Multiple Access with Collision Detection 带有冲突检测能力CSMA Carrier Sense Multiple Access with Collision Avoidance 带冲突避免CSMA Topics discussed in this section:
Figure12.3 Frames in a pure ALOHA network纯ALOHA的帧 Station 1 Frame 1.1 Frame 1.2 Time Station 2 Frame 2.1 Frame 2.2 Time Station 3 Frame 3.1 Frame 3.2 Time Station 4 Frame 4.1 Frame 4.2 Time Collision Collision duration duration 12.5
12.5 Figure 12.3 Frames in a pure ALOHA network 纯ALOHA的帧