(This book systematically introduces and deeply analyzes various network technologies that are popular today; and explains the connections and differences between them in detail. The main contents include: LAN/WAN interconnection, network transmission equipment, ATM, TCP/IP, SONET, Frame Relay, ISDN, SMDS, DSL, X.25 and other popular network technologies and the future development direction of network technology. This book is an excellent treatise on LAN/WAN network technology, with detailed content and easy-to-understand language. It can also be used as network technology training materials and reference books.)