1 INTRODUCTION 1.1 Network goals 1.2 Applications of networks 2 THE PHYSICAL LAYER 3 THE MEDIUM ACCESS SUBLAYER 4 THE DATA LINK LAYER 4.1 Error control 4.2 Flow control 4.3 Link management 5 THE NETWORK LAYER 5.1 Services provided to the transport layer 5.2 Routing congestion 5.3 Internetworking 6 THE TRANSPORT LAYER 6.1 Services provided to the session layer 6.2 Connection management 7 THE SESSION LAYER 7.1 Data exchange 7.2 Dialog management 7.3 Synchronization