Midterm Reviewer - Data Communications PDF

ARUN K. MAJUMDAR DATA COMMUNICATIONS NETWORK - Optical Wireless Communications for - Any system of computer that is USED TO Broadband Global Internet Connectivity...

ARUN K. MAJUMDAR DATA COMMUNICATIONS NETWORK - Optical Wireless Communications for - Any system of computer that is USED TO Broadband Global Internet Connectivity TRANSMIT and /or RECEIVE information (2019) BETWEEN 2 or more LOCATIONS - Communication is all about sharing information, local or remote DATA COMMUNICATION NETWORK ARCHITECTURE - transmission, reception, and processing of OUTLINE the PRODUCTS and SERVICES digital information. necessary for the individual COMPONENTS w/in a DATA COMM. NETWORK to DATA OPERATE TOGETHER - information that is stored in digital form INFORMATION NETWORKS AND NETWORK PROTOCOLS - knowledge or intelligence. GENERAL CLASSIFICATIONS NETWORK CURRENT NETWORKS - set of devices (sometimes called nodes or o Most modern and sophisticated stations) interconnected by media links. networks and protocol LEGACY DATA COMMUNICATIONS NETWORKS o NO ONE really wants to use it - systems of interrelated computers and LEGENDARY computer equipment o ANTIQUATED NETWORK or PROTOCOL finally disappears. INTRANETS - private data communications networks used by many companies to exchange information COMPUTER NETWORK CLASSIFICATION among employees and resources. Broadcast Network FIREWALL - ALL stations and devices on the - converts the Intranet add. system to the network SHARE a SINGLE Public Internet add. system communication channel WORLD WIDE WEB (WWW) o BROADCASTING - server-based application that allows - messages are intended FOR ALL subscribers to access the services offered by Subscribers on the network the Web. o MULTICASTING HISTORY - messages are FOR A SPECIFIC GROUP of Subscribers. 1844: Baltimore and Washington, D.C., with a message “What hath God wrought!” o Frames, blocks, packets - short messages where data is 1874: Baudot invented a telegraph multiplexer propagated through the network 1875: Telephone was invented by Alexander Point-to-Point Graham Bell. - Only have 2 stations, no addresses February 14, 1946: the development of ENIAC by needed. Eckert & Mauchley DATA COMMUNICATIONS PROTOCOLS 1950 - SETS of RULES governing the ORDERLY - computers - inputting information EXCHANGE of DATA - printers for outputting information NETWORK ARCHITECTURE - magnetic tape for storing information - These early computers could process - set of LAYERS and PROTOCOLS that only one job at a time using a technique GOVERN the OPERATION of the called batch processing. NETWORK 1951: the UNIVAC was developed Remington Rand PROTOCOL STACK Corporation and was the first mass-produced - lists of protocol used by a system electronic computer. LAYERED NETWORK ARCHITECTURE 1980: Personal computers - consists of 2 or more independent levels each level has a specific set of responsibilities and functions CONNECTION ORIENTED PROTOCOL OSI LAYER - established between endpoints prior to the OPEN SYSTEMS INTERCONNECTION (OSI) transmission of data. - set of standards for communicating among Setting up the Call computers. Establishing the connection - serve as a structural guideline for exchanging Disconnecting information CHARACTERISTIC LAYERS LAYER 1 – PHYSICAL LAYER Handshake - occurs between 2 Physical connection and transporting bits station before any data are actually CABLES, WIFI, Hub and Repeater transmitted. Data ACKNOWLEDGEMENT HUB Provide some means of ERROR a connectivity device and a transparent Control device that samples the incoming bit stream CONNECTIONLESS PROTOCOL CARRIER SYSTEM Microwave Satellites Cellular Radio DATA are exchanged in an UNPLANNED fashion WITHOUT prior COORDINATION LAYER 2 – DATA LINK LAYER responsible for providing error-free CHARACTERISTIC communications across the physical link connecting primary and secondary stations WITHOUT Handshake (nodes) within a network HOP-TO-HOP Do not support ERROR Control DELIVERY) SYNTAX LAYER 3 - NETWORK LAYER (END TO END) provides details that enable data to be routed - format of the data in which DATA are SENT between devices in an environment using multiple networks, subnetworks, or both. SEMANTICS LAYER 4 – TRANSPORT LAYER (SERVICE TO - refers to the MEANING of EACH Section of SERVICE) DATA. controls and ensures the end-to-end integrity of the data message propagated through the network between 2 devices. STANDARD LAYER 5 – SESSION LAYER - authoritative principles or rules that imply a Responsible for network availability model or pattern 3 Basic Function of Session Layer 1. Session Management 2. Authentication DATA COMMUNICATIONS STANDARDS 3. Authorization guidelines that have been generally accepted by the data communication LAYER 6 – PRESENTATION LAYER industry. provides independence to the application processes by addressing any code or syntax conversion 2 BASIC TYPES OF STANDARD PROPRIETARY (CLOSED) STANDARD 3 basic function of Presentation Layer - manufacture & controlled by 1 1. Translation COMPANY. 2. Data Compression OPEN SYSTEM STANDARDS 3. Encryption/Decryption - ANY COMPANY can PRODUCE COMPATIBLE equipment, however, ROYALTY MUST BE PAID to the ORIGINAL LAYER 7 – APPLICATION LAYER COMPANY. highest layer in the hierarchy Two Types of Service Elements a. CASEs (Common Application Service Elements) useful to a variety of application processes. b. SASEs (Specific Application Service Elements) satisfy particular needs of application processes. LOCAL AREA NETWORK Computer Network Topologies LAN POINT TO POINT - Small network - contains exactly two hosts - Interconnection of computers and peripheral devices Main reason of interconnection of PCs Resource sharing BUS TOPOLOGY Applicative programs sharing Increment productivity COMPONENTS OF A LAN STAR TOPOLOGY - connected to a central device, known as hub device, using a point-to-point connection. RING TOPOLOGY COMMUNICATION INFRASTRUCTURE - Use to transfer info NETWORK SERVER MESH TOPOLOGY - Storage and backup - a host is connected to one or multiple hosts. DATA COMMUNICATIONS TYPES OF COMPUTER NETWORKS Full Mesh: All hosts have a point-to-point connection to every other host in the network. PERSONAL AREA Partially Mesh: Not all hosts have point-to-point - smallest network connection to every other host. - connectivity ranges up to 10 meters TREE TOPOLOGY LOCAL AREA NETWORK (LAN) - network spanned inside a building and operated under single administrative system. Network LAN Technologies DAISY CHAIN 1. ETHERNET (IEEE 802.3) - connects all the hosts in a linear fashion - high probability of data collision, uses Carrier Sense Multi Access/Collision Detection HYBRID TOPOLOGY (CSMA/CD) technology to detect collisions. - A network structure whose design contains more than one topology. 2. FAST-ETHERNET (IEEE 803.2) - can run on UTP, Optical Fiber, and wirelessly too. 3. GIGA-ETHERNET (IEEE802.3ab/ IEEE802.3ah) - provides speed up to 1000Mbits/s METROPOLITAN AREA NETWORK (MAN) - expands throughout a city such as cable TV network. WIDE AREA NETWORK - covers a wide area which may span across provinces and even a whole country. INTERNETWORK - internet, largest network in this planet. EX: E-mail, Blogging, Social Media, Marketing and Networking. DATA COMMUNICATION CIRCUITS DATA COMMUNICATIONS CIRCUIT ARRANGEMENTS - provide a transmission path between locations and to transfer digital information from 1 station Circuit configurations is based on the following: to another Number of stations on the circuit STATION (NODE) Type of transmission facility Distance between stations - endpoint where subscribers gain access to the Number of users on each station circuit. COMMUNICATIONS FACILITIES COMMUNICATIONS CIRCUIT CONFIGURATION - physical means of interconnecting stations within a data communications system TWO-POINT CONFIGURATION - Involves only 2 stations. - Transfer of digital information between a main computer MULTIPOINT CIRCUIT - Involves 3 or more stations - Interconnect a single mainframe computer (host) block diagram of a two-station data comms circuit to many personal computers FUNDAMENTAL COMPONENTS OF DATA TRANSMISSION MODES COMMUNICATIONS CIRCUIT SIMPLEX (RECEIVE-ONLY, TRANSMIT-ONLY, SOURCE ONE-WAY-ONLY LINES) - generates data - unidirectional; information can be sent in only 1 direction. TRANSMITTER - encodes the source information and converts it to HALF DUPLEX (TWO-WAY-ALTERNATE OR a different form EITHER WAY LINES) - transmission is possible in both directions but not TRANSMISSION MEDIUM at the same time. - Carries the encoded signals from the transmitter to the receiver FULL DUPLEX (TWO-WAY SIMULTANEOUS, DUPLEX, BOTH-WAY LINES) RECEIVER - transmissions are possible in both directions - Converts the encoded signals received from the simultaneously, but they must be between the transmission medium back to their original form same two stations DIGITAL INFORMATION DESTINATION FULL/FULL DUPLEX - Main frame computer, PC & workstation - transmission is in both directions at the same time but not between the same two stations SERIAL AND PARALLEL DATA TRANSMISSION DATA COMMUNICATIONS NETWORKS PARALLEL BY BIT / SERIAL BY CHARACTER - Each bit has its own transmission line. - Any group of computers connected together - All 4 bits can be transmitted simultaneously - The primary balancing in computer networking is - Used for short distance communications speed vs reliability. - Some networking protocols are very reliable but require a significant amount of overhead to provide the desired high level of service. - Other protocols are designed with speed as the primary parameter therefore, forgo some of the reliability features of the connection-oriented protocols. These quick protocols are examples of connection less protocols. SERIAL BY BIT - a single transmission lines - 1 bit can be transmitted at a time - used for long-distance data communications NETWORK COMPONENTS, FUNCTIONS, AND FEATURES Characteristics of NICs include the following: - Computer networks are like snowflakes, no two are the same. 1. The NIC constructs, transmits, receives, and processes data to and from a PC and the connected network. SERVERS 2. Must have a NIC installed - computers that hold shared files, programs, and the network operating system. 3. NIC is generally installed in a computer as a daughterboard Operation of a file server: 4. Each NIC has a unique six-byte media access control o A user (client) requests a file from the file (MAC) address, server o The file server sends a copy of the file to MAC address is sometimes called: their questing user. o File servers allow users to access and - Physical manipulate disk resources stored on - Hardware other computers. - Node - Ethernet Characteristics - LAN address o File servers are loaded with files, 5. The NIC must be compatible with the network (i.e., accounts, and a record of the access Ethernet—10baseT or token ring) to operate properly rights of users or groups of users on the network. LOCAL OPERATING SYSTEM o The server provides a shareable virtual - allows personal computers to access files disk to the users (clients). o File mapping schemes are implemented Examples: to provide the virtualness of the files - MS-DOS o Security systems are installed and - PC-DOS configured to provide the server with the - Unix required security and protection for the - Macintosh files. - OS/2 o Redirector or shell software programs - Windows 3.11 located on the users’ computers - Windows 95 transparently activate the client’s - Windows 98 software on the file server. - Windows 2000 - Linux CLIENTS (CUSTOMERS) - access and use the network and shared network resources. TRANSMISSION MEDIA (CHANNELS, LINKS, OR LINES) - facilities used to interconnect computers in a network, such as twisted-pair wire, coaxial cable, and optical fiber cable NETWORK OPERATING SYSTEM SHARED DATA - program that runs on computers and servers - data that file servers provide to clients such as that allows the computers to communicate data files, printer access programs, and e- over a network mail. SHARED PRINTERS AND PERIPHERALS Popular NOS: - hardware resources provided to the users of the - Unix network by servers. - Novell Net Ware - AppleShare NETWORK INTERFACE CARD - Macintosh System 7 - Special expansion card - IBM LAN Server - The NIC prepares (formats) and sends data, - Compaq OpenVMS a receives data, and controls data flow between the computer and the network. - Microsoft Windows NT Server DATA COMMUNICATIONS CODES - character codes, character sets, symbol ERROR CONTROL codes, or character languages. - The data can be corrupted during the BAUDOT CODE (Telex code or a fixed-length transmission. block code) TYPES OF ERROR - first fixed-length character code developed for machines BIT ERROR - 5bit character code - single bit error ASCII CODE - the Bell System model 33 teletype code as BURST ERROR the United States of America Standard Code - 2 or more bits in the data unit have changed for - Information Exchange (USASCII), better known as ASCII-63 - ITU as International Alphabet No. 5, in the United States as ANSI standard X3.4-1986 (R1997), and by the International Standards Organization as ISO-14962 (1997). - 7bit character code HOW TO DETECT ERRORS? EBCDIC CODE (extended binary-coded decimal interchange code) - 8-bit fixed length character set developed in 1962 by the International Business Machines Corporation (IBM) - 8 bits or 256, codes are possible, although only 139 of the 256 codes are actually assigned characters. BAR CODES - series of vertical black bars separated by vertical white bars (called spaces). Classification of Bar Codes ✓ Discrete code o has spaces or gaps between characters. o EX: Code 39 ✓ Continuous Code o does not include spaces between ERROR DETECTION TECHMIQUES characters o EX: Universal Product Code 1. Vertical Redundancy Check (VRC) - parity check. ✓ 2S Code - It can detect single bit error. o stores data in two dimensions in - It can detect burst error only if the number is contrast odd. - VRC 1: odd VRC 0; even CODE 39 - Code 3 of 9 and 3 of 9 Code 2. Longitudinal Redundancy Check (LRC) - 36 unique codes representing the 10 digits - A block of bits is organized in blocks and and 26 uppercase letters columns. - Also called as two-dimensional parity. 3. Checksum Checksum = Check + sum Sender side – Checksum Creation Receiver side – Checksum Validation 4. Cyclic Redundancy Check (CRC) UNIVERSAL PRODUCT CODE - develop by the grocery industry in 1970’s to identify their products. (The National Association of Food Chains) ACRONYM ARPA Advanced Research Projects Agency ARPANET Advanced Research Projects Agency Network NSF National Science Foundation NSFNET National Science Foundation Network FTP File Transfer Protocol HTTP Hypertext Transfer Protocol SMTP Simple Mail Transfer Protocol STANDARDS ORGANIZATIONS FOR DATA COMMUNICATIONS ISO. INTERNATIONAL STANDARDS ORGANIZATION ITU INTERNATIONAL TELECOMMUNICATIONS UNION IEE. INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS ANSI. AMERICAN NATIONAL STANDARDS INSTITUTE EIA. ELECTRONICS INDUSTRY ASSOCIATION TIA. TELECOMMUNICATIONS INDUSTRY ASSOCIATIONS IAB - INTERNET ARCHITECTURE BOARD IETF. INTERNET ENGINEERING TASK FORCE IRTF. INTERNET RESEARCH TASK FORCE