T.C. Chang Introduction to Data Communication IE551 Spring 2004

T.C. Chang Introduction to Data Communication IE551 Spring 2004 01/06/23 8-1

T.C. Chang Need: DATA COMMUNICATION Design file exchange. Part program downloading. Person to person communication - e-mail, talk, video conferencing. System control: commands, status data, sensor data Remote login. 50% of plant floor computer system cost are allocated to networking costs. How to make control devices talk to each other. Solutions: Point-to-point communication Networking 01/06/23 8-2

T.C. Chang AN CPU ALU Control Unit registers address bus data bus control bus I/O Memory 01/06/23 8-3

T.C. Chang AN I/O BUFFER internal to a computer address bus decoder select clock buffer Data Bus from control bus 01/06/23 external device read/write 8-4

T.C. Chang ASCII CODE High Bits low 01/06/23 000 001 010 011 100 101 110 0000 NUL DLE SP 0 @ P \ p 0001 SOH DC1 ! 1 A Q a q 0010 STX DC2 " 2 B R b r 0011 ETX DC3 # 3 C S c s 0100 EOT DC4 4 D T d t 0101 ENQ NAK % 5 E U e u 0110 ACK SYN & 6 F V f v 0111 BEL ETB ' 7 G W g w 1000 BS CHN ( 8 H X h x 1001 HT EM ) 9 I Y i y 1010 LF SUB * : J Z j z 1011 VT ESC ; K [ k { 1100 FF FS , L \ l 1101 CR GS - M ] m } 1110 SO RS . N n 1111 DE SI US / ? O o 111 8-5

T.C. Chang SERIAL COMMUNICATION UART TX UART TX RV RV parallel GND Device 1 DTE 01/06/23 GND cable Device 2 DCE 8-6

T.C. Chang INTERFAC E DTE: Data Terminal Equipment (terminal) DCE: Data Circuit-terminating Equipment (modem, computer) DTE DTE DCE DCE RS 232C, RS 422, X.21 RS232C 25 pin connector DB25 connector twisted pair balanced 1 -3V 100 kbps at 1200m 0 3V 10 mbps at 12 m 20 kbps 15 m unbalanced signal 01/06/23 RS 422 37 pin or 9 pin X.21 packet transmission mode or unbalanced (RS 423A) 3 kbps at 1000 m 300 kbps at 10 m 8-7

T.C. Chang TRANSMITTING THE LETTER 'S' Volt letter 'S' 1 start 1 parity bit 1 0 0 1 0 1 0 2 stop bits 0 time 1 start bit 7 data bit 1 parity bit 2 stop bits sec/bit Even parity Baud rate 1/ clock 01/06/23 8-8

T.C. Chang PIN NAME TO DTE TO DCE 1 FG Frame Ground 2 TD 3 RD 4 RTS 5 CTS 6 DSR 7 SG 8 CD 9 FUNCTION EIA AA 101 Transmitted Data BA 103 Receive Data BB 104 Request to Send CA 105 Clear to Send CB 106 Data Set Ready CC 107 Signal Ground AB 102 Carrier Detect CF 109 - Reserved - - 10 - Reserved - - 11 - Unassigned - - 12 (S)CD Sec. Carrier Detect SCF 122 13 (S)CTS Sec. Clear to Send SCB 121 14 (S)TD Sec. Transmitted Data SBA 118 15 TC Transmitter Clock DB 114 16 (S)RD Sec. Received Data SBB 119 17 RC Receiver Clock DD 115 18 - Unassigned - - 19 (S)RTS Sec. Request to send SCA 120 20 DTR Data Terminal Ready CD 108.2 21 SO Signal Quality Detector CG 110 22 RI Ring Indicator CE 125 Data Rate Selector CH 111 Data Rate Selector CI 112 Ext. Transmitter Clock DA 113 Unassigned - - 23 01/06/23 RS 232 24 (E)TC 25 - CCITT 8-9

T.C. Chang MODEM CCITT V.XX standards (Consultative Committee for International Telephone STANDARDS and Telegraph) V.22, V.22 bis. : synchronous/asynchronous data transmission, full-duplex operation over 2 wire at 1,200 bps (2,400 and 1,200 bps for V.22 bis) data rate. V.32 : synchronous/asynchronous data transmission, full-duplex operation over 2 wire at 9,600 bps data rate. V.32 bis: synchronous/asynchronous data transmission, full-duplex operation over 2 wire at 14,400, 12,000, 9,600, 7,200, 4,800 bps data rate. V.34 bis: synchronous/asynchronous data transmission, full-duplex operation over 2 wire at 28.8k, . Modem-connection negotiations (training and retraining), may reduce the data rate due to line noise. Fastrain: may go up the speed as well. Duplex: full (two lines, two way), half (one line, one way) Bell standard: Bell 103, 300 bps; Bell 201B: 2,400 bps, full duplex on 4 wire, or 1,200 bps, half duplex on 2 wire. Bell 201C: 2,400 bps, half duplex on 2 wire; Bell 208 A & B: 4,800 bps Data compression: compress the data before transmission. 01/06/23 8 - 10

T.C. Chang address decoder Data Bus from computer 01/06/23 PARALLEL INTERFACE ADAPTER enable Data Bus Buffer Chip Select and Read Write Control Control Register Data Direction Register Peripheral Interface Data Output Register 8 - 11

T.C. Chang IEEE 488 Standard digital interface for programmable instrumentation HP interface GPIB (General Purpose Interface Bus) 1 mbps 01/06/23 8 - 12

T.C. Chang POLLING st at us o f input po rt lo op no st at us o f o ut put po rt no 01/06/23 ye s lo ad input byt e t o t he ac cum ulat o r ye s send a byt e t o t he o ut put p ort 8 - 13

T.C. Chang INTERRUP T highpriorityinterruptroutine lowpriorityinterruptroutine mainCPUloop 01/06/23 8 - 14

T.C. Chang NETWORKS No longer a point-to-point connection. Many devices connected together and information can be passed by one device to any of the devices on the network. Local area network - Ethernet, FDDI, ATM Wide area network High speed local network 01/06/23 8 - 15

T.C. Chang COMPARISO N LAN High Speed Local Computerized Branch Network (HSLN) Exchange (CBX) Transmission medium Twisted pair Coaxial cable Optical fiber CATV coax Twisted pair Topology bus, tree, ring bus star Speed 1-20 Mbps 50 Mbps 9.6-64 Kbps Max Distance 25 Km 1 Km 1 Km Switching Technique Packet Packet Circuit (no delay) 100's - 1000's 10's 100's-1000's Attachment Cost low high very low Applications Computers Main frame to Voice disk drive Terminal-t-terminal No. of Devices Supported Terminals Terminal-t-host 01/06/23 8 - 16

T.C. Chang GLOSSARY OF SELECTED TERMS Bandwidth: frequency range used by the communication system. Baseband: use voltage difference (digital) Broadband: use coaxial cable and analog (RF) signals. Higher band width, multiple channels on the same cable. Digital signals are modulated on a carrier frequency. CTV: 5 mbps per channel Carrier from 5-300 M Hz Carrier: A continuous frequency capable of being modulated or impressed with a second (information) signal. DDS (Dataphone Digital Service): AT&T service in which data is transmitted in digital rather than analog form. Need no modem. FDDI (Fiber Distributed Data Interface): ANSI standard for fiberoptic links with data rates up to 100 mbps. LED or laser light source; 2 km for unrepeated data transmission at 40 mbps. ISDN (Integrated Services Digital Network): mixed digital-transmission services, basic rate at 144 kbps, and primary rates at 1.544 and 2.048 mbps. 01/06/23 8 - 17

T.C. Chang GLOSSARY OF SELECTED TERMS Medium Access Control: controls which device on the network get the to send data to the medium. CSMA/CD Token Ring Token Bus Packet: small chunk of data. Protocol: a set of rules that governs the operation of functional units to achieve communication. TCP/IP: Transport protocols concurrently with existing Ethernet. NFS: network file system - file system sharing, remote disk mounting. 01/06/23 8 - 18

T.C. Chang IDEAL LAN CHARACTERISTICS high speed: greater than 10 mega bits per second low cost: easily affordable on a microcomputer and/or machine controller high reliability/integrity: low error rates, fault tolerant, reliable expandability: easily expandable to install new nodes installation flexibility: easy to be installed in an existing environment interface standard: standard interface across a range of computers and controllers. 01/06/23 8 - 19

T.C. Chang CABLE S insulators ground wire core wire Coaxial cable 01/06/23 Twist pair cable 8 - 20

T.C. Chang LAN TOPOLOGIES Ring Star Bus 01/06/23 8 - 21

T.C. Chang ETHERNET Terminator Tap Transceiver RF T/S 50 ohmcoaxial cable T/S digital Computer C1 T/S T/S C3 C4 Repeater C2 bridge T/S 01/06/23 8 - 22

T.C. Chang COLLISION DETECTION CSMA/CD protocol t0 A A begin transmission a is the time for signal to travel to B, B transmission time 2a t0 a- e A B begin transmission before signal reach B B A B detects collison B t0 a t0 2a- e A 01/06/23 A detects collison just before the end of transmission. B 8 - 23

T.C. Chang ETHERNET CONNECTIONS Twisted-pair Ethernet (10BASE-T) Standard Ethernet (10BASE5) segment length Š 500 m segment length Š 100 m cable Š 4 km unshielded twisted-pair cable transceiver cable Š 50 m devices connected to a hub in a star configuration between transceivers Š 2.5 m Š 100 transceivers per segment 50 ohm terminators Hub connected to the standard Ethernet Use twisted-pair transceiver. computers ThinNet Ethernet (10BASE2) segment length Š 185 m cable length Š 4 km T-connectors, 0.5 m between each T-connector Hub Š 30 connections 50 ohm terminators T-connectors plugged directly to the Ethernet card. 01/06/23 computers 8 - 24

T.C. Chang A TOKEN RING computer A B repeater direction of token and data packet D C Only one token is passed around the network. The device who has the token may transmit. 01/06/23 8 - 25

T.C. Chang A TOKEN LogicalBUS ring C A C B D A B E C D D E predecessor D B Add a new node A B E successor Token passing network. Whoever has the token may transmit one or more packets. When it is done, or the time has expired, it passes the token to the next station. 01/06/23 8 - 26

T.C. Chang ISO/OSI MODEL Device B Device A User Program User Program Layer 7 Application Application Layer 6 Presentation Presentation Layer 5 Session Session Layer 4 Transport Transport Layer 3 Network Network Layer 2 Data Link Data Link Layer 1 Physical Physical medium 01/06/23 8 - 27

T.C. Chang LAYERED PROTOCOL 2. DATA LINK LAYER flow control error control Activate, maintain and deactivate the link. Error free transmission on the same network. Detecting noise. 3. NETWORK LAYER provides the transparent transfer of data between transport entities. Responsible for establishing, maintaining, and terminating connections (between networks). Use globally unique node address. 4. TRANSPORT LAYER Ensures that data units are delivered error-free, in sequence, without no losses or duplications. Connection management 01/06/23 8 - 28

T.C. Chang LAYERED PROTOCOL 5. SESSION LAYER Controlling the dialogue between applications. Dialogue type: two-way simultaneous (TWS), two-way alternate (TWA), one-way, etc. Recovery after network breakage. 6. PRESENTATION LAYER Syntax of the data exchanged between application entities. e.g. teletext, videotex, encryption, virtual terminal. 7. APPLICATION LAYER Common application services (CASE) Specific application services (SASE) Management file transfer job transfer 01/06/23 8 - 29

T.C. Chang Preamble A PACKET SYN code Physical layer message Data link layer message Network layer message Transport layer message Session layer message Presentation layer message Application layer message Data Checksum Postamble 01/06/23 SYN code 8 - 30

T.C. Chang MAP 2.1 STANDARD Layer MAP implementation Layer 7 ISO FTAM {DP} 8571 Application File Transfer Protocol Manufacturing Messaging Format Standard (MMFS) MAP Directory Services MAP Network Management Layer 6 Presentation NULL/MAP transfer Layer 5 ISO Session{IS} 8327 Session Basic Combined Subset & Session Kernel, Full Duplex Layer 4 Transport ISO Transport{IS} 8073 Class 4 Layer 3 ISO Internet{DIS} 8473 Network Connectionless, SubNetwork Dependent Convergence Protocol Layer 2 ISO Logical Link Control {DIS} 8802/2 (IEEE 802.2) Data Link Type 1, Class 1 ISO/IEEE 802.4 Token Passing Bus Medium Access Control 01/06/23 Layer 1 ISO Token Passing Bus{DIS} 8802/4 (IEEE 802.4) Physical 10 Mbps Broadband 8 - 31

T.C. Chang ROUTE R INTERNET network layer data link physical layer Network A 01/06/23 network layer data link physical layer Network B network layer data link physical layer Network C 8 - 32

T.C. Chang An Integrated Corporate Communication Network Corporate Ethernet Bridge Division TOP network Corporate Offices Factory CRT IBM SNA network CAD/CAM CRT Gateway Terminal server Data base MAP Backbone Gateway Office TOP network Router Robots MAP Sub Network Machines PLCs Gateway Robots 01/06/23 Gateway Gateway Office Finance/accounting Corporate TOP network PLCs Vendor Network 8 - 33

T.C. Chang TOP Technical Office Protocol: for the office network Similar to MAP except the physical layer uses Ethernet 10Base5 01/06/23 8 - 34

T.C. Chang COMMUNICATION ON UNIX NETWORK INTERFACE LAYER PROTOCOL LAYER SOCKET LAYER when a communication is desired, create a socket get Protocol protocol Application e.g. ftp telnet IN buffer Out buffer out packet In packet Network interface Hardware determines the route of travel 01/06/23 8 - 35

T.C. Chang EXAMPLE internet domain for TCP protocol s socket(AF INET, sock stream,0); /* create a socket*/ connect(s,&server, sizeof(server)); /* establish connection */ write(s,buf,sizeof(buf)); /* send data */ close(s); /* close socket*/ 01/06/23 8 - 36

T.C. Chang TCP/IP PROTOCOL User Program Layer 7 Application Layer 6 Presentation Layer 5 Session Layer 4 Transport T CP Layer 3 Network IP Layer 2 Data Link Layer 1 Physical ET HERNET UDP: User datagram protocol FTP: File transfer protocol SMTP: Simple mail transfer protocol TELNET: Virtual terminal protocol 01/06/23 UD P FT P SM T P T ELNET TCP: Transmission control protocol IP: Internetwork protocol 8 - 37

T.C. Chang DATA COMMUNICATION CO AND INTERNET TERMINAL COMPUTER TCP/IP LAN COMPUTER PC/MAC COMPUTER COMPUTER NY UUCP PC/MAC TCP/IP Ethernet COMPUTER COMPUTER IN Phone line modem TERMINAL PC/MAC 01/06/23 8 - 38

T.C. Chang WHAT DO WE WANT SEND AND RECEIVE ELECTRONIC MAIL TRANSFER DATA REMOTE LOG IN OTHER COMPUTERS ACCESS INFORMATION RESOURCES IN THE WORLD COMMUNICATE WITH PEOPLE OF COMMON INTEREST RETRIEVE AND ARCHIVE DATA AND APPLICATION PROGRAMS OPEN TO THE INFORMATION DATA HIGHWAY 01/06/23 8 - 39

T.C. Chang DATA COMMUNICATION ALTERNATIVES Phone and fax BBS (bulletin board system) run your own. Commercial information vendors: CompuServe, Prodigy, America Online, GEnie Internet connection 01/06/23 8 - 40

T.C. Chang COMPUTER NETWORK Domains Information Vendor America Online GEnie Prodigy CompuServe MS Network EDU GOV MIL COM NET ORG TW - Taiwan CU - Cuba CA - Canada FR - France JP - Japan IR - Iran IQ - Iraq . Internet References: Krol, E., the Whole Internet User's Guide & Catalog, O'Reilly & Associates, Inc., 1992, 376 pages. ( 24.99, 1-800-998-9938, [email protected]) Hahn, H. & R. Stout, The Internet Complete Reference, Osborne McGraw-Hill, 1994. 817 pages. 01/06/23 8 - 41

T.C. Chang WHAT IS INTERNET? Internet is a loosely connected wide area network. It is a group of worldwide information resources open to everyone on the network. Some characteristics of the internet: Origin: Arpanet sponsored by US DOD in the 1970s. Who may participate? Anyone who pays a nominal fee to connect to a nearby network and agrees to follow a set of rules. Who runs the network? Nobody is in charge. Who pays for it and to whom? The organization who is connected to the network must pay it own segment of the network. There is no central organization to collect the payment. What kind of hardware is needed to run the network? Any kind of computer hardware. How to connect to a network? Find a closest node and negotiate the connection. What is the limitation of using it? No direct commercial use. What is most widely used operating system on the net? Unix. How big is the network? Too big and growing to be even bigger every minute. 01/06/23 8 - 42

T.C. Chang COMMONLY AVAILABLE TOOLS ON INTERNET TCP/IP: The network protocol used on the net. Packet switching and mail gram. Each computer on the net is assigned a unique IP address, e.g. 128.54.16.1. DNS domain name system does translation between names and the IP address. E-MAIL: [email protected] userid @ machine. local domain. domain Telnet: remote login a terminal session on an UNIX machine. Ftp: remote file copying. Usenet: news/discussion groups. Top cover from ethnic politics to science fiction. Archie: archive software and articles. Archie servers provide index of information available on public archives. Gopher, Veronic, and Jughead: easier way to explore internet resources. Wais: information search on the internet. Finger: look up someone on the net. Talk talk to someone on the net (two way communication). 01/06/23 8 - 43

T.C. Chang WORLD WIDE WEB (WWW) HyperText interface to the Internet. Allows users to explore the network effortlessly. Developed at CERN, the particle physics institute in Geneva Switzerland. HTTP: HyperText Transfer Protocol URL: Uniform Resource Locator "http://www.ecn.purdue.edu" HTML: HyperText Markup Language VRML: Virtual Reality Markup Language Client/Server: client is a software application that extract service from a server. Home Page: A start-up document that serves as your home base. Tools (Browsers): Lynx : for text terminal Mosaic: graphics, Mac Mosaic, PC Mosaic, X- Mosaic (NCSA product), Netscape, etc. 01/06/23 8 - 44