nals 10.4Analog and Digital Data Circuits 10.4.1 Analog Data Circuits 10.4.2 Unloaded Circuits 10.4.3 Wet VS. Dry Circuits 10.4.4 Broadband or Wideband Analog 10.4.5 Digital Circuits 10.4.6 Fiber: Analog or Digital? 10.5DCE: Data Circuit-Terminating Equipment 10.5.1 Analog DCE: Modems 10.5.2 Digital DCE: CSUs, DSUs, and More 10.6Point-to-Point Circuits 10.6.1 Parallel 10.6.2 Serial 10.7 Multidrop Circuits 10.7.1 IBM Mainframe Circuits 10.7.2 Cable Television Distribution 10.8LANs: Local Area Networks 10.9Wide Area Networks 10.9.1 Basic Components of a WAN 10.9.2 Routers, Network Addresses and Packets 10.10 TCP/IP for Networking 11 HOW DATA IS FORMATTED FOR TRANSMISSION In this chapter, we'll put in place a solid understanding of the key concepts of IP packets and LAN frames, beginning with the fundamentals, to ensure that you have a solid foundation on which to build an understanding of routers, bandwidth-on-demand services and the Internet. 11.1 Basics 11.1.1 Bits 11.1.2 Bytes 11.1.3 Words 11.1.4 Control and Data 11.2Number Systems 11.2.1 Decimal 11.2.2 Binary 11.2.3 Hexadecimal 11.2.4 Common Use for Hexadecimal 11.3"Asynchronous" PAGE 9 TELECOM 101 REFERENCE BOOK TERACOM TRAINING INSTITUTE 11.3.1 Coding, Framing and Error Control 11.3.2 ASCII Code Set 11.3.3 Extended ASCII 11.3.4 EBCDIC 11.3.5 Framing: Start and Stop Bits 11.3.6 Parity Checking 11.3.7 No Parity 11.4Frames: "Synchronous" 11.4.1 Exchanging Frames 11.4.2 Components of a Frame 11.4.3 CRC: Cyclic Redundancy Checking 11.5Packets 11.6Packets vs. Frames 11.7IP Packets 12 MODEMS Understand how modems transmit 1s and 0s over analog circuits. We'll explain the techniques all modems use, jargon like baud rate and half duplex, and review current voiceband modem standards and what connection speeds to expect. 12.1 Data over the PSTN 12.1.1 Recap: Circuit-Switching and the PSTN 12.1.2 Recap: The Voiceband 12.1.3 Why Not Use Pulses? 12.2Representing Data in the Voiceband 12.2.1 Amplitude Shift Keying (ASK) 12.2.2 Frequency Shift Keying (FSK) 12.2.3 Phase Shift