Chapter 1: Introduction to Data Communications and Networking - PDF

Because learning changes everything.® Gthgerorations Chapter 01 Introduction Data Communications and Networking, With TCP/IP protocol suite Sixth Edition Behrouz A. Forouzan © 2022 McGraw Hill, LLC. All rights reserved. Authorized only for instructor use in the classr...

Because learning changes everything.® Gthgerorations Chapter 01 Introduction Data Communications and Networking, With TCP/IP protocol suite Sixth Edition Behrouz A. Forouzan © 2022 McGraw Hill, LLC. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior written consent of McGraw Hill, LLC.  Ch Chaptera3: Outline t.si 1.1 DATA COMMUNICATIONS Bi gnetworks.bg'S network 1.2 NETWORKS we use whey communicati 1.3 NETWORK TYPES for Data 1.4 PROTOCOL LAYERING Resource sharing 1.5 TCP/IP PROTOCOL SUITE Is HIM 1.6 THE OSI MODEL jetter Ennui da LEG.FI.w Delivery Accuracy t m AH I t.fm time line PYad 5 is Ls © McGraw Hill, LLC 2 I Figure 1.1 Five components of data communication set of u Wig jus t faedgrowneagnati's bing.FI Is issue If Loading… transmission media protocol Access the text alternative for slide images.  © McGraw Hill, LLC 3 1.1.1 Components A data communications system has five components: 1. Message 2. Sender 3. ReceiverIgtmati gi paired fiper 4. Transmission Medium J EggL war caper wireless and.fr waue 5. Protocol software most't Bluetooth 81 (Figure 1.1) 4 s ft G.i ds gf.fi g't ggender se W i  f f µ g © McGraw Hill, LLC 4 1.1 DATA COMMUNICATIONS Data communication is the exchange of data between two devices via some form of transmission media. It depends on four characteristics: 1. Delivery W't 2. Accuracy Loading…HIS 3. Timeliness 4. Jitter © McGraw Hill, LLC 5 1.1.2 Message Information today comes in different forms such as text, numbers, images, audio, and video. © McGraw Hill, LLC 6 Text O Text is represented as a bit pattern using Unicode. mme © McGraw Hill, LLC 7 Numbers I Numbers are represented in binary. © McGraw Hill, LLC 8 Images Images are represented as bit patterns using either RGB or YCM. bit pattern forgets © McGraw Hill, LLC 9 Audio J Audio refers to the recording or broadcasting of sound or music, represented as analog or digital signals. g © McGraw Hill, LLC 10 Video Videos can be a continues images or a combination of images. ROB Bit pattern us Loading… ycµ © McGraw Hill, LLC 11 1.1.3 Data Flow M I Communication between two devices can be simplex, half-duplex, and duplex as shown in Figure 1.2. of between 2devices Data flowTypeSg ommunication simpler half duplex duplet duplex fan  © McGraw Hill, LLC 12 Figure 1.2 Data flow (simplex, half-duplex, full-duplex) mpater supercomputer I I j a r rp Tea Server 0 not on thesame time a  Access the text alternative for slide images. © McGraw Hill, LLC 13 Simplex In simplex mode the communication is in one direction. Only one of the two connected devices can send or receive. bg I6W'S w List a © McGraw Hill, LLC 14 Half-Duplex In half-duplex, each station can send or receive, but not at the same time. S B A WI HE D f Him I if JI g © McGraw Hill, LLC 15 Full-Duplex In full-duplex, both stations can send or receive at the same time. B A ant M 8 Him go in duplex f © McGraw Hill, LLC 16 1-2 NETWORKS I A network is the interconnection of a set of devices capable of communication. In this definition, a device can be a host such as a large computer, desktop, laptop, workstation, cellular phone, or security system. A device in this definition can also be a connecting device such as a router a switch, a modem that changes the form of data, and so on. © McGraw Hill, LLC security 17 f is reliability erformanaapsr 1.2.1 Network Criteria A network must be able to meet a certain number of criteria. The most important of these are: performance, reliability, and security. throwpa.Hglo ss.s 62 latency1Delay © McGraw Hill, LLC 18 Performance 0 Em Performance can be measured in many ways, including transit time T.im and response time. Transit time is 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. I © McGraw Hill, LLC 19 Reliability Correct In addition to accuracy of delivery, network reliability is measured comma of failure, the time it takes a link to recover from a by the frequency failure, and the network’s robustness in a catastrophe. a I complete reliable correct T T T Reliable © McGraw Hill, LLC 20 Security Network security issues include protecting data from unauthorized access, protecting data from damage and development, and I implementing policies and procedures for recovery from breaches and data losses. security p g W ft El stack jib protocol © McGraw Hill, LLC 21 1.2.2 Physical Structures Before discussing networks, we need to define some network structures. © McGraw Hill, LLC 22 Types of Connection A network is two or more devices connected through links. A link is a communications pathway that transfers data from one device to another. There are two possible types of connections: point-to-point and multipoint (see Figure 1.3) W © McGraw Hill, LLC 23 my Figure 1.3 Types of connection I  D z i points1 0 IF a communication Access the text alternative for slide images. is F © McGraw Hill, LLC 24 Physical Topology The term physical topology refers to the way in which a network is laid out physically. Two or more devices connect to a link; two or more links form a topology. The topology of a network is the geometric representation of the relationship of all the links and linking devices (usually called nodes) to one another. There are four basic topologies possible: mesh, star, bus, and ring. i geig a  © McGraw Hill, LLC 25 complete graph Dej Figure 1.4 A fully connected mesh topology In node Id S n=5 if1 nodes s 10 links f It 074 Edges is AT hardtomanage 3 I setup Bmantaincenceand I I tf fornetwork hard I'M Hedge sus 4 effortGusty Id bye node if exposure 84kt f path s low security me  Access the text alternative for slide images. © McGraw Hill, LLC 26 Figure 1.5 A star topology Isis 6 s IEEE'finiti F Tuttunt sqq performance Intl wtf gfgwich needy switch Ji y j traffic control overthe I swim j 61 f f j y o fI m iI EstitterainYtraticiani like  Star DI ICH Fofoigg © McGraw Hill, LLC 27 c S wit I I I bas l b 791 It Figure 1.6 A bus topology M M 46149 protocol T 4 low level y fd.tk a network physical f www two address 41 dress a Exposure d II j O f can be easily an see 0 O no  anger Access the text alternative for slide images. s i s © McGraw Hill, LLC 28 Figure 1.7 A ring topology hodesdk9end9siFYF neXtlfgprevj.qI node B Ji Hip m M I if MOTE Loading… connection.IT x  Access the text alternative for slide images. © McGraw Hill, LLC 29 1-3 NETWORK TYPES A network can be of two types: LANs and WANs Egg PAN personal microtv Arena network W MAN gg is LAN's a WANS © McGraw Hill, LLC 30 1.3.1 Local Area Network (LAN) h A local area network (LAN) is usually privately owned and connects some hosts in a single office, building, or campus. ET tar  JW LAN F Ng © McGraw Hill, LLC 31 I g p Figure 1.8 An isolated LAN in the past and today cominp end pie cabletop Swift onngection  star topology Access the text alternative for slide images. © McGraw Hill, LLC 32 1.3.2 Wide Area Network (WAN) A wide area network (WAN) is also a connection of devices capable of communication. a WAN has a wider geographical span, spanning a town, a state, a country, or even the world. is G I w s f B it pei 11 I ab I s's A W AN  I point to point 1 switched mesh PAD WAN WAN point © McGraw Hill, LLC 33 Point-to-Point WAN I A point-to-point WAN is a network that connects two communicating devices through a transmission media (cable or 7mm air). Figure 1.9 shows an example of a point-to-point WAN. © McGraw Hill, LLC 34 if dig 4J Figure 1.9 A point-to-point WAN I t capacity's f'S f KE Routers w Rbi'd of F W µ big bigrouter router I  m Cable Air Access the text alternative for slide images. © McGraw Hill, LLC 35 Switched WAN G'mesh topology A switched WAN is a network with more than two ends. A switched WAN is used in the backbone of global communication today. Figure 1.10 shows an example of a switched WAN. 2Antero A iii E'W Pcs It Is i if mesh is rja Higgs Network 8 Th Wey b t pc's ja HQ µ y j f gg l W k w to sail a swim a Wwii To  it T © McGraw Hill, LLC 36 Figure 1.10 A switched WAN  Access the text alternative for slide images. © McGraw Hill, LLC 37 Internetwork N zag Today, it is very rare to see a LAN or a WAN in isolation; they are connected to one another. When two or more networks are connected, they make an internetwork, or internet. internet im 8thb'It between different organizations if Internet ft Internet eme y i Hitomi I 1 within theorganization intranets fm fits © McGraw Hill, LLC 38 Figure 1.11 An internetwork made of two LANs and one WAN Pelt  internet's Access the text alternative for slide images. © McGraw Hill, LLC 39 I ivetw if Figure 1.12 A heterogeneous network made of WANs and LANs if a me I  s NG ackbones Job d w assisi o'S gustiness c A HE j II bowowge battlenecks singlepoint g Access the text alternative for slide images. offailior © McGraw Hill, LLC 40 1.3.3 The Internet An internet (note the lowercase i) is two or more networks that can communicate with each other. The most notable internet is called the Internet (uppercase I) and is composed of millions of interconnected networks. Figure 1.13 shows a conceptual (not geographical) view of the Internet. i Af y wissggwJj81gsIojljsiof natisopn.a.lt g.atTIPW1os6bs4WtFBWFHoH m µ's gylwdjm.SI © McGraw Hill, LLC 41 1.3.4 Accessing the Internet The Internet today is an internetwork that allows any user to become part of it. The user, however, needs to be physically connected to an ISP. The physical connection is normally done through a point-to-point WAN.  © McGraw Hill, LLC 42 point-to-point Using Telephone Networks Ig I S w is Fi datat.bg fsHg gbif.odHsF'He HiToday most residences and small businesses have telephone 2 service, which means they are connected to a telephone network. Since most telephone networks have already connected themselves to the Internet, one option for residences and small businesses to connect to the Internet is to change the voice line between the residence or business and the telephone center to a point-to-point WAN.  i © McGraw Hill, LLC 43 Using Cable Networks More and more residents over the last two decades have begun using cable TV services instead of antennas to receive TV broadcasting. The cable companies have been upgrading their cable networks and connecting to the Internet. A residence or a small business can be connected to the Internet by using this service. © McGraw Hill, LLC 44 Using Wireless Networks Wireless connectivity has recently become increasingly popular. A household or a small business can use a combination of wireless and wired connections to access the Internet. With the growing wireless WAN access, a household or a small business can be connected to the Internet through a wireless WAN.  t m U W T H E 81 61 9 64 H © McGraw Hill, LLC 45 Direct Connection to the Internet A large organization or a large corporation can itself become a local ISP and be connected to the Internet. This can be done if the FE a high-speed WAN from a organization or the corporation leases g carrier provider and connects itself to a regional ISP. For example, a large university with several campuses can create an internetwork and then connect the internetwork to the Internet.  internet worm Internet © McGraw Hill, LLC 46 1-4 PROTOCOL LAYERING We defined the term protocol before. In data communication and networking, a protocol defines the rules that both the sender and connection x f receiver and all intermediate devices need to follow to be able to communicate directly. I is WITH  2 parts f © McGraw Hill, LLC 47 241 as I laffrowaened FIE's towns 1.4.1 Scenarios Bi blackbox 11 g approach Let us develop two simple scenarios to better understand the need for protocol layering. Aww  I 1 email © McGraw Hill, LLC 48 First Scenario A large organization or a large corporation can itself become a local ISP and be connected to the Internet. This can be done if the organization or the corporation leases a high-speed WAN from a carrier provider and connects itself to a regional ISP. gingered  WW1 Systymatic design Eat if if p'tab depuggig.IT Accuracy M its system 111K gy © McGraw Hill, LLC 49 Figure 1.14 A single-layer protocol y J  Access the text alternative for slide images. © McGraw Hill, LLC 50 Second Scenario In the second scenario, we assume that Ann is offered a higher- level position in her company, but needs to move to another branch located in a city very far from Maria. They decide to continue their conversion using regular mail through the post office. However, they do not want their ideas to be revealed by other people if the letters are intercepted. They use an encryption/decryption  technique. T T © McGraw Hill, LLC 51 Figure 1.15 A three-layer protocol  Access the text alternative for slide images. © McGraw Hill, LLC 52 1.4.2 Principles of Protocol Layering Let us discuss two principles of protocol layering. © McGraw Hill, LLC 53 First Principle of protocol layering The first principle dictates that we need to make each layer to perform two opposite task in each direction. 0 O it  recieved Scud relieve each AtwooppositeTasks in © McGraw Hill, LLC direction 54 Second Principle of protocol layering The second principle dictates that two objects under each layer should be identical.  i i n © McGraw Hill, LLC 55 no 1.4.3 Logical Connections After following the above two principles, we can think about logical connection between each layer as shown in Figure 1.16. © McGraw Hill, LLC 56 Figure 1.16 Logical connection between peer layers  Access the text alternative for slide images. © McGraw Hill, LLC 57 1-5 TCP/IP PROTOCOL SUITE protocol stack Now we can introduce the TCP/IP (Transmission Control Protocol / Internet Protocol). This is thewhat is protocol suite used in the Internet today. TCP IP suite KP IP layers complete ordered correct Application Reliability 5 Data 6 Shortestpal 4 transport logica Addressing Ip layer Network controlon 058 I's 3 Addressing 1 physical 2 Data link signals 1Analog signals Digital physicallayer signalprocessing convert 084 2 Signals waves © McGraw Hill, LLC 58 Figure 1.17 Layers in the TCP/IP protocol suite to jjdlo.bg Ch layers Ihs if I 9 I d is correct ig cha 3am I f t 614681649 Player 2 logicalAddressing ios'm ch 7e8 HE si ones and zeros is limb.pk E omg s Egg ed'M wireless Wd physics.gg Ch 31 4 datalink i IHH do layer Ofy rfantro1_ FI JB signalprocessing.gg Zerosand analogsignals Ch 2 IF erosion.es 9 onse Digitalsignals WW1 Access the text alternative for slide images. © McGraw Hill, LLC 59 1.5.1 Layered Architecture To show how the layers in the TCP/IP protocol suite are involved in communication between two hosts, we assume that we want to use the suite in a small internet made up of three LANs (links), each with a link-layer switch. We also assume that the links are  connected by one router, as shown in Figure 1.18. IP © McGraw Hill, LLC 60 TCP through an internet Figure 1.18 Communication i h s computerA computer I T If wi B z t i P µ zfsmd.ME owIgHdznetw.rkinterfaafsE Is Router 1M network terface Itdd J h a Waitress bow cards µ H G 1pm Address TBT defied ftJWH 2 Ul js Access the text alternative for slide images. © McGraw Hill, LLC 61 1.5.2 Brief Description of Layers After the above introduction, we briefly discuss the functions and duties of layers in the TCP/IP protocol suite. Each layer is discussed in detail in the next five parts of the book. To better understand the duties of each layer, we need to think about the  logical connections between layers. Figure 1.19 shows logical connections in our simple internet. W routers p Ec level to layering ojyebioIfw.giievdxe.Q peer © McGraw Hill, LLC 62 Figure 1.19 Logical connections between layers in TCP/IP riw.io is law  hopN next hop tohop Access the text alternative for slide images. © McGraw Hill, LLC 63 Figure 1.20 Identical objects in the TCP/IP protocol suite mi s is  u i iI protocol paIket.is be frame Idoin Ij D l e d thereisno message here it'sjust Zero's andones Access the text alternative for slide images. © McGraw Hill, LLC 64 1.5.3 Description of Each Layer After understanding the concept of logical communication, we are ready to briefly discuss the duty of each layer. Our discussion in this chapter will be very brief, but we come back to the duty of each  layer in next five parts of the book. © McGraw Hill, LLC 65 Physical Layer We can say that the physical layer is responsible for carrying individual bits in a frame across the link. The physical layer is the lowest level in the TCP/IP protocol suite, the communication  between two devices at the physical layer is still a logical communication because there is another, hidden layer, the transmission media, under the physical layer. We discuss Physical Layer in Chapter 2. physical layer 2 media transmission © McGraw Hill, LLC 66 Data Link Layer We have seen that an internet is made up of several links (LANs and WANs) connected by routers. When the next link to travel is determined by the router, the data-link layer is responsible for  2 taking the datagram and moving it across the link. We discuss Data-Link Layer in Chapter 3. s frames © McGraw Hill, LLC 67 Figure 1.13 The Internet today  Access the text alternative for slide images. © McGraw Hill, LLC 68 Network Layer The network layer is responsible for creating a connection between the source computer and the destination computer. The communication at the network layer is host-to-host. However, since  there can be several routers from the source to the destination, the routers in the path are responsible for choosing the best route for each packet. We discuss Network Layer in Chapter 4. Ft error.rotE H F g trattoria 2 k e © McGraw Hill, LLC 69 Transport Layer The logical connection at the transport layer is also end-to-end. The transport layer at the source host gets the message from the application layer, encapsulates it in a transport-layer packet. In  other words, the transport layer is responsible for giving services to the application layer: to get a message from an application program running on the source host and deliver it to the corresponding application program on the destination host. transmits user datagrams without first creating a logical connection. We discuss Transport Layer in Chapter 9. © McGraw Hill, LLC 70 Application Layer The logical connection between the two application layers is end- to-end. The two application layers exchange messages between  each other as though there were a bridge between the two layers. However, we should know that the communication is done through all the layers. Communication at the application layer is between two processes (two programs running at this layer). To communicate, a process sends a request to the other process and receives a response. Process-to-process communication is the duty of the application layer. We discuss Application Layer in Chapter 10. © McGraw Hill, LLC 71 t.ba a.e Interconnection 1-6 OSI MODEL Open Systems Although, when speaking of the Internet, everyone talks about the TCP/IP protocol suite, this suite is not the only suite of protocols  defined. Established in 1947, the International Organization for Standardization (ISO) is a multinational body dedicated to worldwide agreement on international standards. Almost three- fourths of the countries in the world are represented in the ISO. An ISO standard that covers all aspects of network communications is the Open Systems Interconnection (OSI) model. It was first introduced in the late 1970s. Ew © McGraw Hill, LLC 72 Figure 1.21 The OSI model JizdsflTcplIP yIcsmpres.iojnDataI1 xes.f  e SLI Hud marshling serelization Dialogcontrolandserialization is pata f.si Mei's Dialog 1 bgi sencroliu.IT Reciever senders ft W Ip Husks Iie UsGig cPlIP Access the text alternative for slide images. © McGraw Hill, LLC 73 1.6.1 OSI versus TCP/IP When we compare the two models, we find that two layers, session and presentation, are missing from the TCP/IP protocol suite.  These two layers were not added to the TCP/IP protocol suite after the publication of the OSI model. The application layer in the suite is usually considered to be the combination of three layers in the OSI model, as shown in Figure 1.22. © McGraw Hill, LLC 74 Figure 1.22 TCP/IP and OSI model  Access the text alternative for slide images. © McGraw Hill, LLC 75 1.6.2 Lack of OSI Model’s Success The OSI model appeared after the TCP/IP protocol suite. Most experts were at first excited and thought that the TCP/IP protocol  would be fully replaced by the OSI model. This did not happen for several reasons, but we describe only three, which are agreed upon by all experts in the field. © McGraw Hill, LLC 76 End of Main Content dad  zig Because learning changes everything.® www.mheducation.com © 2022 McGraw Hill, LLC. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior written consent of McGraw Hill, LLC.