r Esperanto Layer Seven: The Application Layer Layer Six: The Presentation Layer More About Compression Image Coding Schemes Windows Bitmap (BMP) The Joint Photographic Experts Group (JPEG) The Graphics Interchange Format (GIF) Contents JPEG vs. GIF Tag Image File Format (TIFF) Compressing Moving Images The MPEG Standards MPEG-1 MPEG-2 MPEG-3 MPEG-4 MPEG-7 The Session Layer Switched Networks Store-and-Forward Switching Packet Switching Connection-Oriented Networks Connectionless Networks The Network Layer Routing Responsibilities Routing Protocols Congestion Control Back to the E-Mail Message The Data Link Layer Error Recovery Options Practical Implementations The Physical Layer OSI Summary Other Protocol Stacks Chapter 2 Questions Chapter 3 Telephony Miracle on Second Avenue The History of Telephony The Telephone Network In the Belly of the Beast Network Topology Into the Central Office Interoffice Trunking Conserving Bandwidth: Voice Transport Framing and Formatting in T1 Beginnings: D1 Framing Evolution: D4 Today: Extended Superframe The Rest of the World: E1 Up the Food Chain: From T1 to DS3 and Beyond From DS1 to DS3 Contents SONET Advantages: Mid-Span Meet Improved OAM&P Multipoint Circuit Support Unintrusive Monitoring New Services SONET Evolution The SONET Frame SONET Bandwidth The STS-N Frame The STS-Nc Frame Overhead Modifications in STS-Nc Frames Transporting Subrate Payloads Virtual Tributaries Creating Virtual Tributaries Creating the Virtual Tributary Superframe SONET Synchronization One Final Thought Next-Generation SONET SONET Summary SDH Nomenciature The SDH Frame STM Frame Overhead Overhead Details Voice Digitization The Nature of Voice The Network Multiplexing Voice Digitization Pulse Code Modulation (PCM) Alternative Digitization Techniques Adaptive Differential Pulse Code Modulation (ADPCM) Continuously Variable Slope Delta Linear Predictive Coding (LPC) Digital Speech Interpolation (DSI) Enter the Modern World Voice-over IP VolP Evolution VoIP Implementation Carrier Class IP Voice IP-Enabled