Note Flow control refers to a set of procedures used to restrict the amount of data that the sender can send before waiting for acknowledgment. 流量控制就是一系列过程，用来限制发送方在 等到确认之前发送的数据数量。 11.11
11.11 Flow control refers to a set of procedures used to restrict the amount of data that the sender can send before waiting for acknowledgment. 流量控制就是一系列过程，用来限制发送方在 等到确认之前发送的数据数量。 Note
Note Error control in the data link layer is based on automatic repeat request, which is the retransmission of data. 数据链路层的差错控制基于自动重复请求， 即重传数据。 11.12
11.12 Error control in the data link layer is based on automatic repeat request, which is the retransmission of data. 数据链路层的差错控制基于自动重复请求， 即重传数据。 Note
11-3 PROTOCOLS几种协议 Now let us see how the data link layer can combine framing, flow control,and error control to achieve the delivery of data from one node to another.The protocols are normally implemented in software by using one of the common programming languages.To make our discussions language- free,we have written in pseudocode a version of each protocol that concentrates mostly on the procedure instead of delving into the details of language rules. 数据链路层如何将成帧，流量控制和差错控制结合起来，实 现节点到节点间的数据传输。通常用某种通用的程序语言实 现相关协议。但我们采用伪代码，主要关注数据链路实现的 过程，而非程序语言实现细节。 11.13
11.13 11-3 PROTOCOLS 几种协议 Now let us see how the data link layer can combine framing, flow control, and error control to achieve the delivery of data from one node to another. The protocols are normally implemented in software by using one of the common programming languages. To make our discussions languagefree, we have written in pseudocode a version of each protocol that concentrates mostly on the procedure instead of delving into the details of language rules. 数据链路层如何将成帧，流量控制和差错控制结合起来，实 现节点到节点间的数据传输。通常用某种通用的程序语言实 现相关协议。但我们采用伪代码，主要关注数据链路实现的 过程，而非程序语言实现细节
Figure1l.5 Taxonomy of protocols discussed in this chapter几种协议G Protocols For noiseless For noisy channel channel Simplest Stop-and-Wait ARQ Stop-and-Wait Go-Back-N ARQ Selective Repeat ARQ 11.14
11.14 Figure 11.5 Taxonomy of protocols discussed in this chapter 几种协议分类
11-4 ,NOISELESS CHANNELS无噪声信道 Let us first assume we have an ideal channel in which no frames are lost,duplicated,or corrupted.We introduce two protocols for this type of channel. 首先，我们假定有一种不会丢失帧、复制帧或损坏 帧的理想信道。包括两种协议：不使用流量控制和 使用流量控制，但不使用差错控制。 Topics discussed in this section: Simplest Protocol 最简单的协议 Stop-and-Wait Protocol停等协议 11.15
11.15 11-4 NOISELESS CHANNELS 无噪声信道 Let us first assume we have an ideal channel in which no frames are lost, duplicated, or corrupted. We introduce two protocols for this type of channel. 首先，我们假定有一种不会丢失帧、复制帧或损坏 帧的理想信道。包括两种协议：不使用流量控制和 使用流量控制，但不使用差错控制。 Simplest Protocol 最简单的协议 Stop-and-Wait Protocol 停等协议 Topics discussed in this section: