1.The data link layer in system A,for example,communicates with the network layer of system A,the physical layer of system A,and the data link layer in system B.Figure 5 illustrates this example.例如,系统A中的数据链接层与该系统中的物理层——网络层以及系统B中的数据链接层进行通信,详见图5.
2.The seven OSI layers use various forms of control information to communicate with their peer layers in other computer systems.这七个OSI层通过不同形式的控制信息与其它计算机系统中的同级层进行通信.
3.Each layer in the source system adds control information to data,and each layer in the destination system analyzes and removes the control information from that data.
在源系统中的每一层都在数据库中添加控制信息,而目标系统中的每一层则对该数据库中的控制信息进行分析和移除.
4.After the application layer performs these actions,the data is passed to the recipient software application in system B,in exactly the form in which it was transmitted by the application in system A.在应用层实施完这些功能之后,数据会被传送到系统B中的接收应用软件,其被传送的方式与其从系统A中发送出来的方式一样
5.At the data link layer,however,all the information passed down by the network layer(the Layer3 header and the data)is treated as data.但在数据链路层,所有网络层传送的信息都被视为有效数据.
6.Different data link layer specifications define different network and protocol characteristics,including physical addressing,network topology,error notification,sequencing of frames,and flow control.不同的数据链路层参数代表了不同的网络协议特性,包括物理地址、网络拓扑、错误通知、帧数排序和数据流控制.
7.because this layer defines the logical network layout,routers can use this layer to determine how to forward packets.由于这一层决定了逻辑网络的布置,路由器可以利用这一层决定如何转发数据包.
8.flow control manages data transmission between devices so that the transmitting device does not send more data than the receiving device can process.数据流管理设备间的数据传输,保证发送设备所发出的数据不超过接收设备所能接受的范围.
9.Communication sessions consist of service requests and service responses that occur between applications lacated in different network devices.通讯层包括位于不同网络设备的应用软件中的服务请求和服务响应
10.This layer interacts with software applications that implement a communicating component.Such application programs fall outside the scope of the OSI model.该层与装有通信组件的应用软件相互作用,这种应用程序超出了OSI的模型范围.