计算子专业英语第七章.pptVIP

Notes [1] ?Open Systems Interconnection is a standard reference model for communication between two end users in a network. 开放式互连系统是网络中两个用户进行通信的标准参考模型。 [2] ?The session layer establishes and manages a dialogue between communicating and systems. 会话层在通信与系统之间建立和管理对话。 [3] ?It specifies what communication services are to be available to a computer system to allow it to co-operate with other systems in carrying out tasks. 它(应用层)指定了哪种通信服务在计算机系统里可以用来和其他系统共同完成任务。 [4] ?None of the layers are intended to be seen or used directly by the operators or other human users of a computer system. 任何一层都不可能让操作员或者系统里的其他用户看到或直接使用。 Exercises Ⅰ. ?Choose the correct answer. 1. ?In OSI reference model, which layer ensures error-free transmission of data between two directly connected systems? _______ ? a. physical layer b. data link layer c. transport layer d. network layer 2. ?Which layer provides routing and switching functions necessary to move data from an originating system through intermediary nodes to the destination system? ________ ? a. ?physical layer b. ?data link layer c. ?transport layer d. ?network layer 3. The TCP/IP model has four layers, from the bottom to up there are________. ? a. data link layer, network layer, transport layer, application layer ? b. network layer, data link layer, transport layer, application layer ? c. transport layer, network layer, transport layer, application layer ? d. data link layer, network layer, application layer, transport layer Ⅱ. ?Answer the questions. 1. ?What’s the function of the network reference model? 2. ?What’s the difference between OSI reference model and TCP/IP reference model? Tips Network Protocol Network protocol defines the rules and conventions for communication between network devices. 1. ?ARP—Address Resolution Protocol ARP converts an IP address to its corresponding physical network address. ARP i