ITT 300 - CHAPTER 1 INTRODUCTION.pdf

ITT300 INTRODUCTION TO DATA COMMUNICATION AND NETWORKING CHAPTER 1 INTRODUCTION ADAPTED FROM: BEHROUZ A. FOROUZAN LEARNING OUTCOMES At the end of this lesson, students should be able to: 1. Identify the main components in a communications sy...

ITT300 INTRODUCTION TO DATA COMMUNICATION AND NETWORKING CHAPTER 1 INTRODUCTION ADAPTED FROM: BEHROUZ A. FOROUZAN LEARNING OUTCOMES At the end of this lesson, students should be able to: 1. Identify the main components in a communications system 2. Describe the criteria for an effective communications system 3. Differentiate three methods of data flow 4. Draw four types of network topology 5. Clarify the advantages and disadvantages of each network topology 6. Identify three categories of network 7. Describe the Internet protocols and standards W H AT I S DATA ? Data Is a raw and unorganized facts. The term data refers to information in any form which is agreed by two parties. Data information today comes in different forms such as texts, numbers, images, audios and videos. ACTIVITY 1 W H AT I S DATA C O M M U N I C AT I O N S ? When we communicate we are sharing information Local sharing, e.g face to face Remote sharing, e.g over some distances Data: information being shared, e.g text, numbers, images, audio, video Data Communications: exchange of data between two (or more) devices via some transmission medium  Delivery the data must be delivered to the correct destination Accuracy EFFECTIVE the data received must be accurate DATA representation of the data sent C O M M U N I C AT I O N S Timeliness the data should be delivered within a reasonable time CO M P O N E N T S O F DATA C O M M U N I CAT I O N S C O M P O N E N T S O F DATA C O M M U N I C AT I O N S Message – the information to be communicated. Popular forms of information include text, numbers, pictures, audio , and video Sender – the device that sends the data. It can be a computer, workstation, telephone, television Receiver – the device that receives the message Transmission medium – the physical path by which a message travels from sender to receiver Protocol – set of rules that govern data communications (represents an agreement between the communicating devices)  Half-Duplex each station can both Simplex transmit and receive, but the communication is not at the same time. unidirectional. Only When one device is one of the two devices sending, the other can on a link can transmit; only receive. Example: the other can only walkie-talkie receive. Example: keyboard and monitor Full-Duplex both stations can transmit and receive simultaneously. Example: telephone DATA F LO W NETWORKS Network: a set of devices (referred as nodes) connected by communication links Most networks use distributed processing, in which a task is divided among multiple computers.  A number must be able to meet a certain number of criteria: Performance including transit time and response time. Depends on number of users, type of transmission medium, capability of hardware, efficiency of software Transit time: the amount of time required for a message to travel from one device to another Response time is the elapsed time between an inquiry and a response. Reliability: measured by frequency of failure, the time it takes a link to recover from a failure, and the network’ robustness in a catastrophe Security: protecting data from unauthorized access, protecting data from damage, recovery NETWORK CRITERIA COMMUNICATION LINKS TYPE OF CONNECTION Point-to-point – provides a dedicated link between two devices Spatially – Temporally – several devices users must take use the link turns simultaneously Multipoint – more than two specific devices share a single link (either spatially or temporally) NETWORK TO P O LO GY Arrangement of nodes of a computer network Topology = layout  PHYSICAL TOPOLOGY AND LOGICAL TOPOLOGY Physical topology – placement of various nodes. Logical topology – deals with the data flow in the network. NETWORK TOPOLOGY M E S H TO P O LO GY Each node is directly connected to every other nodes in the network. Fault tolerant and reliable ADVANTAGES DISADVANTAGES Fault tolerant Issues with broadcasting messages. Reliable Expensive and impractical for large network.  S TA R TO P O LO GY Every node is connected to a central node called hub or switch. Centralized management. All traffic must past through the hub or switch. ADVANTAGES DISADVANTAGES Easy to design and implement. Single point of failure affects the whole network. Centralized administration. Bottleneck due to overloaded Switch/Hub. Scalable. Increase cost due to Switch/Hub MAY 24 17 B U S TO P O LO GY All data transmitted between nodes in the network is transmitted over this common transmission medium and can be received by all nodes in the network simultaneously. a signal containing the address of the intended receiving machine travels from a source machine in both directions to all machines connected to the bus until finds the intended recipient. ADVANTAGES DISADVANTAGES Only one wire - less expensive Not fault tolerant (no redundancy) Suited for temporary network Limited cable length Node failures does not affect others No security  R I N G TO P O LO GY A ring topology is a bus topology in a closed loop. Peer-to-Peer LAN topology. Two connections: one to each of its ADVANTAGES DISADVANTAGES nearest neighbors. Unidirectional Performance better than Bus Unidirectional. Single point of failure will affect the Sending and receiving data takes whole network. place with the help of TOKEN. Can cause bottleneck due to Increase in load, decrease in weak links performance All nodes with equal access No security MAY 24 19 NETWORKS Demand for any user to communicate with any other any machine/user Require: Communication Software Communication Network Technologies: WANS LANS DECEMBER 8 20 C AT E G O R I E S O F N E T W O R K S Local Area Network (LAN) Wide Area Network (WAN) Metropolitan Area Network (MAN) DECEMBER 8 21 LOCAL AREA NETWORKS Small coverage area, e.g building campus Owned and operated by organizations owning end- devices Higher internal (per user) data rates compared to WANS How to arrange nodes in a LAN? How to share LAN amongst multiple users? Example technologies: Ethernet, Wireless LAN MAY 24 22 MAN Extend over an entire city May be a single network or may be a means of connecting a number of LANs into a larger network so that resources may be shared LAN- to-LAN MAY 24 23 WAN Span a large geographical area Require crossing of public right-of-ways Rely on links of common carriers (telecommunication companies) Carries data of multiple organizations How to find path across a network? How to deliver data across the network? Example technologies: ATM, Frame Relay, SDH MAY 24 24 THE INTERNET Origins Evolve frome US Department of Defence research network, ARPANET (developed in 1969) Used packet switching technology (whereas telephone networks used circuit switching) Development and standardization of the Internet suite of protocols: TCP/IP What is The Internet? Collection of networks connected together using common software: Internet Protocol (IP) Although network technologies differ, any computer can communicate with any other computer (providing they are using IP) 25 SERVICE PROVIDERS MAY 24 26 PROTOCOLS Protocols – defines what is communicated, how it is communicated and when it is communicated Key elements of a protocol : syntax, semantic, timing Syntax – structure or format of data, meaning the order in which they are presented. Example: the first 8 bits to be the address of sender, the second 8 bits to be the address of the receiver and the rest of the stream to be the message MAY 24 27 PROTOCOLS(CONTINUE) Semantics – The meaning of each section of bits. How is a particular pattern to be interpreted, and what action is to be taken based on that interpretation? Example: does an address identify the route to be taken? Timing – when data should be sent and how fast they can be sent. Example: If a sender produces data at 100Mbps but the receiver can process data at only 1 Mbps, the transmission will overload the receiver and data will be largely lost MAY 24 28 S TA N DA R D S Guidelines to manufacturers, vendors, government agencies and other service providers to ensure the kind of interconnectivity necessary in today’s marketplace and in international communications Data communication standards fall into 2 categories: De facto – standards that have not been approved by an organized body but have been adopted as standards through widespread use De jure – standards that have been legislated by an officially standard organizations MAY 24 29 S TA N DA R D S ( C O N T ’ D ) Examples: De facto XML based standards – for data representation and exchange on the Internet Microsoft Word DOC (over all other old PC word processors) – one of the best known de facto standards supported by all office applications De jure Wireless 802.11n Internet TCP / IP protocol ASCII character set MAY 24 30 S TA N DA R D O R G A N I Z AT I O N S Standards Creation Committees Forums Regulatory Agencies MAY 24 31 S TA N DA R D C R E AT I O N COMMITTEES International Organization for Standardization (ISO) –Multinational body whose membership is mainly from the standards creation committees of various governments throughout the world. International Telecommunication Union–Telecommunication Standards Sector (ITU-T) – devoted to the research and establishments of standards for telecommunications in general and for phone and data systems in particular American National Standards Institute (ANSI) Institute of Electrical and Electronics Engineers (IEEE) – the largest professional engineering society in the world, aiming to advance theory, creativity and product quality in the fields of engineering, electronics and radio. Also, developing international standards for computing and communications. Electronic Industries Association (EIA) – non profit organization devoted to the promotion of electronics manufacturing concerns (defining physical connection interfaces and electronic signalling specifications for data connections). 32 FORUMS Telecommunications technology development is moving faster than the ability of standards committees to ratify standards To facilitate the standardization process, many special interest groups have developed forums made up of representatives from interested corporations The forums work with universities and users to test, evaluate and standardize new technologies The forums are able to speed acceptance and use of technologies in the telecommunications community Forums present their conclusions to the standard bodies MAY 24 33 R E G U L ATO R Y A G E N C I E S All communications technology is subject to regulation by government agencies such as Federal Communications Commission (FCC) The purpose of these agencies is to protect the public interest by regulating radio, television, and cable communications MAY 24 34 I N T E R N E T S TA N DA R D S Internet standards – a thoroughly tested specification that is useful to and adhered to by those who work with the Internet Specification begins as an Internet draft before it attains Internet standard status Internet draft – a working document with no official status and a 6-month lifetime Upon recommendation from the authorities, a draft may be published as a Request for Comment (RFC) MAY 24 35 ACTIVITY 2