[外文翻譯]數(shù)據(jù)鏈路層/The Data Link Layer
內(nèi)包含中文翻譯和英語原文，內(nèi)容豐富，建議下載閱覽。

①中文頁數(shù) 16

中文字數(shù) 14889

②英文字數(shù) 22

英文頁數(shù) 8671

③ 摘要
在這一章中，我們將研究網(wǎng)絡第二層——數(shù)據(jù)鏈路層的設計原則。我們將主要研究的是在數(shù)據(jù)鏈路層上，兩臺相連的機器之間進行可靠、有效通信而涉及到的一些算法。這里的相連，意思是指兩臺機器通過通信信
道進行物理連接．信道意思是：概念上像一條線路〔即同軸電纜、電話線或者點到點的無線通道)；能像線路一樣，這也暗示了它的一個本質(zhì)特征，是接收到的比特同發(fā)送出去的順序完今相同。
剛開始，也許會認為這個問題很簡單，覺得沒有什么內(nèi)容需要學習——機器A只是把比特放到線路上，而機器B也只是取走比特。不幸的是，通信線路偶爾也會出錯。而且，它們只有有限的數(shù)據(jù)速率，并且：在同一數(shù)據(jù)的發(fā)送和接收之間的傳輸時延也不為零。這些限制對于數(shù)據(jù)的有效傳輸有重要的影響。 用于通信過程的協(xié)議必須把所有這些因素都加以考慮。這些協(xié)議正是本章的主題。

In this chapter we will study the design principles for layer 2, the data link layer. This study deals with the algorithms for achieving reliable, efficient communication between two adjacent machines at the data link layer. By adjacent, we mean that the two machines are connected by a communication channel that acts conceptually like a wire (e.g., a coaxial cable, telephone line, or point-to-point wireless channel). The essential property of a channel that makes it ''wirelike'' is that the bits are delivered in exactly the same order in which they are sent.
At first you might think this problem is so trivial that there is no software to study—machine A just puts the bits on the wire, and machine B just takes them off. Unfortunately, communication circuits make errors occasionally. Furthermore, they have only a finite data rate, and there is a nonzero propagation delay between the time a bit is sent and the time it is received. These limitations have important implications for the efficiency of the data transfer. The protocols used for communications must take all these factors into consideration. These protocols are the subject of this chapter.


④ 關(guān)鍵字 數(shù)據(jù)鏈路層的設計原則/stud the design principles for layer