说明：  本书内容包括:概述;物理层;点对点信道的数据链路层;局域网;广域网;网络互连;运输层;应用层;计算机网络的安全等。
(The contents of this book include: overview; physical layer; point to point channel data link layer; LAN; Wan; network interconnection; transport layer; application layer; computer network security.)