1_ICS343-Chapter_1_Introduction.pptx

Chapter 1 Introductio n Introduction: 1-1 Chapter 1: introduction Objectives:  Introduction to data communications; defines their components and the types of data exchanged.  Introduction networks; defines their criteria and structures (network topologies)  Introduction to dif...

Chapter 1 Introductio n Introduction: 1-1 Chapter 1: introduction Objectives:  Introduction to data communications; defines their components and the types of data exchanged.  Introduction networks; defines their criteria and structures (network topologies)  Introduction to different of networks types: LANs, WANs, and internetworks (internets).  A Brief History of the Internet  Protocols, standards and standards organizations Introduction: 1-2 Why Networks (the Internet) are Important?  An engine of economic growth Electronic business/commerce Online marketplaces Digitization and digital transformation IoT, Cloud Computing, Big Data, AI, etc. In 2023 : 5.3B users globally (66% of the population) 29.3 Billion devices (3.6 per capita) Source: Cisco Annual Internet Report, 2018–2023 Why Networks (the Internet) are Important?  An enabler of societal change Access to knowledge Ease of access to information anywhere in the world Access to news and media Social and personal relationships Introduction: 1-4 Data Communication vs. Networking  Data Communication  Data Networks How to represent data How to find shortest path (encoding) (routing) How to represent signal How to sync sender and (modulation) receiver (flow control) How to check if error How to secure connection occurred (error detection) (encryption) What frequency, power, How applications work, e.g. etc. to use Email, web server, Torrent, Online Gaming. Introduction: 1-5  Data Communication vs. Networking applicatio applicatio n n Networking transport transport network network Data communication link link source physical destination physical Introduction: 1-6 What this course is about?  Learning Outcomes: Identify and describe the basic network components, services, and technologies. List the layered architecture of network protocols (e.g., TCP/IP) and explain core functions at each layer including addressing, routing, internetworking, switching, multiplexing, error and flow control, medium access, and coding. Apply a range of common network applications, utilities, traffic analyzers, and network simulators. Identify potential threats to network resources and describe the basic security mechanisms and protocols. Introduction: 1-7 Data Communications  The term telecommunication, which includes telephony, telegraphy, and television, means communication at a distance (tele is Greek for “far”).  The word data refers to information presented in whatever form is agreed upon by the parties creating and using the data.  Data communications are the exchange of data between two devices via some form of transmission medium such as a wire cable. Introduction: 1-8 Components of Data communications  A data communications system has five components (see Figure 1.1). Introduction: 1-9 Components of Data communications  The message is the information (data) to be communicated. Popular forms of information include text, numbers, pictures, audio, and video  The sender is the device that sends the data message. It can be a computer, workstation, mobile handset, video camera, etc.  The receiver is the device that receives the message.  The transmission medium is the physical path by which a message travels from sender to receiver, e.g., twisted-pair wire, coaxial cable, fiber-optic cable, and radio waves.  A protocol is a set of rules that govern data communications. It represents an agreement between the communicating devices. Introduction: 1-10 Effectiveness of Data Communication  Four fundamental characteristics influence the effectiveness of a data communications system: Delivery: Deliver data to the correct destination. Accuracy: Deliver the data accurately. Timeliness: Deliver data in a timely manner. Real-time transmission requires timely delivery [without significant delay]. Jitter: Variations in packet arrival time. Introduction: 1-11 Data Flow  Communication between two devices can be simplex, half- duplex, or full-duplex as shown in Figure 1.2. In Simplex mode, the communication is unidirectional, as on a one- way street. In half-duplex mode, each station can both transmit and receive, but not at the same time. In full-duplex mode, both stations can transmit and receive simultaneously. Introduction: 1-12 Networks  A network is a set of devices (often referred to as nodes) connected by communication links.  A node can be a computer, printer, or any other device capable of sending and/or receiving data generated by other nodes on the network. Introduction: 1-13 Network Criteria A network must be able to meet a certain number of criteria. The most important of these are performance, reliability, and security.  Performance: examples of performance metrics include delay/response time, and throughput. It depends on the number of users, type of transmission medium, hardware, and software.  Reliability: measured by the frequency of failure, the time it takes a link to recover from a failure, and the network’s robustness in catastrophic incidents.  Security: protecting data from unauthorized access and damage. Also, implementing policies and procedures for recovery from breaches and data losses. Introduction: 1-14 Physical Structures of Networks  The way a link is connecting two or more devices defines the type of Connection: Point-to-Point Multipoint Introduction: 1-15 Physical Topology  Physical Topology refers to the way 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 linked devices (nodes) to one another.  There are four basic types of topologies: Mesh Topology Star Topology Bus Topology Ring Topology Introduction: 1-16 Mesh Topology  In the Mesh Topology every device has a dedicated point-to- point link to every other device.  E.g. n = 5 nodes, #of links = 10 Figure 1.4: A fully-connected mesh topology Introduction: 1-17 Mesh Topology  Advantages Dedicated links → Guaranteed load Robustness: If one link fails, only that link is affected. Privacy and security Easy fault identification and fault isolation  Disadvantages Amount of cabling and the number of I/O ports required Installation and reconnection are difficult Wiring can be greater than the available space The hardware required to connect each link (I/O ports and cable) can be prohibitively expensive. Introduction: 1-18 Star Topology  In Star Topology, each device has a dedicated point-to-point link only to a central controller, usually called a hub.  Unlike mesh topology, if one device wants to send data to another, it sends the data to the controller, which then relays the data to the other connected device. Introduction: 1-19 Star Topology  Advantages A star topology is less expensive than a mesh topology. Easy to install and reconfigure Far less cabling needs to be housed Robustness: If one link fails, only that link is affected.  Disadvantage Single point of failure: If the hub goes down, the whole system is down. Introduction: 1-20 Bus Topology  A bus topology, on the other hand, is multipoint.  One cable acts as a backbone to link all the devices in a network.  A Drop line is a connection running between the device and the main cable.  A Tap is a connector that either splices into the main cable or punctures the sheathing of the cable to create contact with the metallic core. Introduction: 1-21 Bus Topology  Advantages Ease of installation Less cabling; backbone cable can be laid along the most efficient path, and then connected to the nodes by drop lines.  Disadvantage A signal propagating in the bus experiences degradation proportional to the cable length and number of taps. Hence, there is a limit on the number of taps and the distance between taps Difficult fault isolation. A fault or break in the bus cable stops all transmission, even between devices on the same side of the problem. The damaged area reflects signals back in the direction of origin, creating noise in both directions. Introduction: 1-22 Ring Topology  Each device has a dedicated point-to-point connection only with the two devices on either side of it.  Each device incorporates a repeater.  When a device receives a signal intended for another device, its repeater regenerates the bits and passes them along. Introduction: 1-23 Ring Topology  Advantages To add or delete a device requires changing only two connections. Fault isolation is easier. A signal is circulating at all times. If one device does not receive a signal within a specified period, it can issue an alarm.  Disadvantages Unidirectional traffic In a simple ring, a break in the ring (such as a disable station) can disable the entire network. This weakness (above) can be solved by using a dual ring or a switch capable of closing off the break. Introduction: 1-24 Hybrid Topology star ring bus Introduction: 1-25 Categories of Networks  There are different types of networks we encounter in the world today.  A typical criteria for distinguishing one type of network from another considers size, geographical coverage, and ownership. Local Area Network (LAN) Metropolitan Area Network (MAN) Wide Area Network (WAN) Introduction: 1-26 Local Area Network (LAN)  Privately owned and it links devices in a single office, building, or campus.  Limited to a few kilometers.  Hardware or data resources are usually shared.  Topology: Ring, bus, star.  A LAN can be as simple as two PCs and a printer in someone’s home office, or it can extend throughout a company. Introduction: 1-27 Local Area Network (LAN)  Examples: Introduction: 1-28 Local Area Network (LAN)  Examples: Introduction: 1-29 Metropolitan Area Network (MAN)  A network with a size between a LAN and a WAN  Extend over an entire city.  Owned and operated by a private company, e.g. a service provider (ISP) Introduction: 1-30 Wide Area Network (WAN)  Provides long-transmission of data, voice, image, and video information over large geographic areas that may comprise a country, a continent, or even the whole world.  Interconnects connecting devices such as switches, routers, or modems.  It is normally created and run by communication companies (ISPs) and leased by an organization that uses it. Introduction: 1-31 Wide Area Network (WAN)  WANs: a switched WAN vs. a point-to-point WAN Figure 1.9: A Point-to- Point WAN Figure 1.10: A Introduction: 1-32 Switched WAN Wide Area Network (WAN) Figure 1.11: An internetwork made of two LANs and one WAN Introduction: 1-33 Wide Area Network (WAN)  A heterogeneous network made of WANs and LANs Introduction: 1-34 Switching  An internet (note the lowercase i) is a switched network in which a switch connects at least two links.  A switch forwards data from one network to another network when required.  The two most common types of switched networks are: Circuit-switched networks Packet-switched networks Introduction: 1-35 Circuit switching In Circuit-Switched Networks end-end resources are allocated to, reserved for “call” between source and destination  in the diagram, each link has four circuits. call gets 2nd circuit in top link and 1st circuit in right link.  +ve: dedicated resources: no sharing circuit-like (guaranteed) performance  commonly used in traditional -ve: circuit segment telephone is idle if not networks used by call (no sharing) Introduction: 1-36 Packet Switching  In a packet-switched network, the communication between the two networks is done in blocks of data called packets.  It uses a router that has a queue that can store and forward the packets. router Packets 321 source destination queue of packets Introduction: 1-37 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 thousands of interconnected networks.  The Internet consists of several backbones, provider networks, and customer networks.  The Internet has revolutionized many aspects of our daily lives.  It has affected the way we do business as well as the way we spend our leisure time. Introduction: 1-38 The Internet: a “nuts and bolts” view Billions of connected mobile network computing devices: national or global ISP  hosts = end systems  running network apps at Internet’s “edge” Packet switches: forward packets local or (chunks of data) ISP Internet regional  routers, switches home network content Communication links provider  fiber, copper, radio, network datacenter satellite network  transmission rate: bandwidth Networks enterprise  collection of devices, routers, network links: managed by an organization Introduction: 1-39 The Internet Peering point Peering point Figure 1.15: The Internet today Introduction: 1-40  Protocols and Standards  What’s a protocol? Human Network protocols: protocols:  computers (devices) rather than  “what’s the time?” humans  “I have a question”  all communication activity in Internet governed by protocols  introductions Rules for: … specific messages sent … specific actions taken when message received, or other events Introduction: 1-41 Protocols and Standards  What’s a protocol? A protocol defines the format, order of messages sent and received among network entities, and actions taken on message transmission, receipt A protocol defines what is communicated, how it is communicated, and when it is communicated. Introduction: 1-42 Protocols and Standards  Key elements of protocols: Syntax: Refers to the structure or format of the data, meaning the order in which they are presented. Semantics: Refers to the meaning of each section of bits. Timing: When data should be sent and how fast they can be sent Introduction: 1-43 Protocols and Standards  There is a plethora of protocol acronyms we will discuss details of some protocols Introduction: 1-44 Internet Standards and Drafts  Standard is a formalized regulation that must be followed.  There is a strict procedure by which a specification attains Internet standard status. A summary set of steps is given below: 1. A specification begins as an Internet draft with no official status and a six- month lifetime. 2. Upon recommendation from the Internet authorities, a draft may be published as a Request for Comment (RFC). 3. An RFC, during its lifetime, falls into one of six maturity levels: proposed standard, draft standard, Internet standard, historic, experimental, and informational. Introduction: 1-45 Internet Standards and Drafts  RFCs (Request for Comment) are classified into five requirement levels: Required Recommended Elective Limited Not recommended Introduction: 1-46 Standard Organizations  International Organization for Standardization (ISO)  International Telecommunication Union - Telecommunication Standards (ITU-T)  American National Standards Institute (ANSI)  Institute of Electrical and Electronics Engineers (IEEE)  Electronic Industries Association (EIA)  International Engineering Task Force (IETF) Introduction: 1-47  Internet history (reading) 1961-1972: Early packet-switching principles  1961: Kleinrock - queueing  1972: theory shows ARPAnet public demo effectiveness of packet- switching NCP (Network Control  1964: Baran - packet- Protocol) first host-host switching in military nets protocol  1967: ARPAnet conceived first e-mail program by Advanced Research ARPAnet has 15 nodes Projects Agency  1969: first ARPAnet node operational  Internet history (reading) 1972-1980: Internetworking, new and proprietary networks  1970: ALOHAnet satellite network in Hawaii Cerf and Kahn’s internetworking principles:  1974: Cerf and Kahn -  minimalism, autonomy - architecture for no internal changes interconnecting networks required to interconnect  1976: Ethernet at Xerox PARC networks  late70’s: proprietary  best-effort service model architectures: DECnet, SNA,  stateless routing XNA  decentralized control  1979: ARPAnet has 200 define today’s Internet nodes architecture Introduction: 1-49  Internet history (reading) 1980-1990: new protocols, a proliferation of networks  1983: deployment of  new national networks: TCP/IP CSnet, BITnet, NSFnet,  1982: smtp e-mail Minitel protocol defined  100,000 hosts connected to  1983: DNS defined for confederation of networks name-to-IP-address translation  1985: ftp protocol defined  1988: TCP congestion control Introduction: 1-50  Internet history (reading) 990, 2000s: commercialization, the Web, new applications  early 1990s: ARPAnet late 1990s – 2000s: decommissioned  more killer apps: instant  1991: NSF lifts restrictions on messaging, P2P file sharing commercial use of NSFnet  network security to (decommissioned, 1995) forefront  early 1990s: Web  est. 50 million host, 100 hypertext [Bush 1945, Nelson 1960’s] HTML, HTTP: Berners-Lee million+ users 1994: Mosaic, later Netscape  backbone links running at late 1990s: commercialization Gbps of the Web Introduction: 1-51  Internet history (reading) 2005-present: scale, SDN, mobility, cloud  aggressive deployment of broadband home access (10-100’s Mbps)  2008: software-defined networking (SDN)  increasing ubiquity of high-speed wireless access: 4G/5G, WiFi  service providers (Google, FB, Microsoft) create their own networks bypass commercial Internet to connect “close” to end user, providing “instantaneous” access to social media, search, video content, …  enterprises run their services in “cloud” (e.g., Amazon Web Services, Microsoft Azure)  rise of smartphones: more mobile than fixed devices on Internet (2017)  ~18B devices attached to Internet (2017) Introduction: 1-52