COVER -- CONTENTS -- UNIT 1 -- INTRODUCTION -- BASIC CONCEPTS -- THE OSI MODEL -- SIGNALS -- ENCODING -- UNIT 2 -- TRANSMISSION OF DIGITAL DATA: INTERFACES AND MODEMS -- TRANSMISSION MEDIA -- MULTIPLEXING -- ERROR DETECTION AND CORRECTION -- UNIT 3 -- DATA LINK CONTROL -- DATA LINK PROTOCOLS -- LOCAL AREA NETWORKS -- METROPOLITAN AREA NETWORKS (MAN) -- SWITCHING -- UNIT 4 -- INTEGRATED SERVICES DIGITAL NETWORK (ISDN) -- X.25 -- FRAME RELAY -- ASYNCHRONOUS TRANSFER MODE (ATM) -- SYNCHRONOUS OPTICAL NETWORK SONET/SDH -- UNIT 5 -- NETWORKING AND INTERNETWORKING DEVICES -- TRANSPORT LAYER -- UPPER OSI LAYER -- TRANSMISSION CONTROL PROTOCOL (TCP) / INTERNET PROTOCOL -- EMERGING TECHNOLOGIES COMPUTER TELEPHONY AND IP TELEPHONY -- REFERENCES -- INDEX.