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See all Premium member Presentation Transcript Computer Communication NetworksVII Semester – CoreSubject Code: 06EC71 : Computer Communication NetworksVII Semester – CoreSubject Code: 06EC71 By S.V.Uma, Assistant Professor, Department of E&C, R.N.S.I.T Chapter 1Data Communications and Networks Overview : Chapter 1Data Communications and Networks Overview Introduction : Introduction Our goal: Get context, overview, “feel” of networking More depth, detail later in course Approach: descriptive use Internet as example mostly Slide 4: Communications – activity associated with distributing or exchanging information Telecommunications – technology of communications at a distance that permits information to be created any where and used everywhere with little delay Today, it involves Data: digital and analog Voice: spoken word Video: telelcommunication imaging Communication Services & Applications : Communication Services & Applications A communication service enables the exchange of information between users at different locations. Communication services & applications are everywhere. E-mail E-mail server Exchange of text messages via servers Communication Services & Applications : Communication Services & Applications Web Browsing Web server Retrieval of information from web servers Communication Services & Applications : Communication Services & Applications Instant Messaging Direct exchange of text messages Communication Services & Applications : Communication Services & Applications Telephone Real-time bidirectional voice exchange Communication Services & Applications : Communication Services & Applications Cell phone Real-time voice exchange with mobile users Communication Services & Applications : Communication Services & Applications Short Message Service Fast delivery of short text messages What is a communication network? : What is a communication network? The equipment (hardware & software) and facilities that provide the basic communication service Virtually invisible to the user; Usually represented by a cloud Equipment Routers, servers, switches, multiplexers, hubs, modems, … Facilities Copper wires, coaxial cables, optical fiber Ducts, conduits, telephone poles … Definition……… : Definition……… Two or more than two computer systems connected by means of a communication medium like a cable is termed as a Network. Computer Network is a communication system, which links computers and their resources. Why do we need Networking? : Why do we need Networking? Sharing of data and resources Distributing computation among nodes Communicating with Remote I/O devices To share data/file access. Personal Communication (Chat, E-mail) Why do we need networks?-continued.. : Why do we need networks?-continued.. Direct point-to-point communication is not always possible/practical/efficient: Communicating entities can be too far apart for a single link A large set of communicating entities (e.g. telephones) would need impractically large number of connections (full connectivity for N nodes needs N (N – 1) / 2 links) Not all links would be needed all the time! Solution is a communication network BENEFITS OF A NETWORK : BENEFITS OF A NETWORK Following are the benefits of networking which help to increase the productivity: Information Sharing Printer Sharing Hard Disk Sharing Modem Sharing Hardware Sharing Software Sharing Service Access Easy Back-Up Management Security Centralized Administration and Support Many other examples! : Many other examples! Peer-to-peer applications File exchange Searching for Extraterrestrial Intelligence (SETI) Audio & video streaming Network games On-line purchasing Text messaging in PDAs, cell phones (SMS) Voice-over-Internet How are communication networks designed and operated? Basic Communication Network Architecture : Basic Communication Network Architecture Network architecture: the plan that specifies how the network is built and operated Architecture is driven by the network services Overall communication process is complex Network architecture partitions overall communication process into separate functional areas called layers Network Architecture Evolution : Network Architecture Evolution Telegraph networks Telephone networks Internet, Optical & Wireless networks Information transfer per second Next Generation Internet ? Network Architecture Evolution : Network Architecture Evolution Telegraph Networks Message switching & digital transmission Telephone Networks Circuit Switching Analog transmission → digital transmission Mobile communications Internet Packet switching & computer applications Next-Generation Internet Multiservice packet switching network A Communications Model : A Communications Model Source generates data to be transmitted Transmitter Converts data into transmittable signals Transmission System Carries data Receiver Converts received signal into data Destination Takes incoming data Communications Tasks : Communications Tasks Simplified Communications Model - Diagram : Simplified Communications Model - Diagram Slide 23: Data Communication System Components Slide 24: Network Transmission Medium Open air radio, microwaves, satellites, infrared noise signals, collision Optical clear signals, low power and high rate (Gbps) Copper wire Lower cost interfaces Bi-directional What’s a protocol? : What’s a protocol? human protocols: “what’s the time?” “I have a question” introductions … specific msgs sent … specific actions taken when msgs received, or other events network protocols: machines rather than humans all communication activity in Internet governed by protocols-In general a set of rules governing the process Protocols define format, order of msgs sent and received among network entities, and actions taken on msg transmission, receipt What’s a protocol? : What’s a protocol? a human protocol and a computer network protocol: Hi Hi TCP connection req Key Elements of a Protocol : Key Elements of a Protocol Syntax Data formats Signal levels Semantics Control information Error handling Timing Speed matching Sequencing Slide 28: Few Basic Concepts Line Configuration Topology Transmission Mode Categories of Networks Internetworks Slide 30: Point-to-Point Line Configuration Dedicated link between two devices Entire capacity is reserved for transmission between those two devices Slide 31: Point-to-Point Line Configuration Slide 32: Point-to-Point Line Configuration Slide 33: Multipoint Line Configuration More than two specific devices share a single link A spatially or time shared connection Networking : Networking Point to point communication not usually practical Devices are too far apart Large set of devices would need impractical number of connections Solution is a communications network Wide Area Network (WAN) Local Area Network (LAN) Slide 35: The Physical layout of a network is Topology Mesh Network Topology : Mesh Network Topology Type I - Nodes are arranged in grids each node can talk to its neighbors directly non-neighbor nodes needs store-and-forward for communication Slide 37: Type II - Mesh Topology Practical Example: Connection of telephone regional offices Advantages : Advantages Use of dedicated links guarantees that each connection carries its own data load Robust – one faulty link doesn't incapacitate the whole system Privacy & Security guaranteed Fault identification &isolation is easy Disadvantages : Disadvantages Large amount of cabling required More I/O ports required Installation & reconnection are difficult Huge wiring bulk Very expensive Slide 40: Star Network Topology One node at the center as the master node Other nodes linked to the master as slaves slaves communicate via master easy to arbitrate among slaves (master decides) not scalable (the master is the bottleneck) normally used for small networks or those that require predictable performance master failure shuts down the whole net Example: Ethernet, DSL Advantages : Advantages Less Expensive Easy to install & reconfigure (each device needs only one link to connect it to any number of others) Less Connections Additions, moves & deletions involve only one connection Robust – (one link failure doesn’t affect the others) Easy fault identification & isolation Disadvantages : Disadvantages The whole network is dependant on one single point, the hub /master Cabling requirement is high Slide 43: Star Topology Slide 44: Tree Topology Slide 45: Bus Network Topology Every nodes tap into a common medium Signals may collide with each other need to arbitrate who will get the bus capable of broadcasting message (one send & many listen) the common medium is the bottleneck single node failure causes no network failure the medium failure brings down the network Example: (10BASE2, 10BASE5) Ethernet Slide 46: Bus Topology Ring Network Topology : Ring Network Topology Nodes are arranged in a ring One node receives from its predecessor & sends to its successor arbitrate who can access the ring messages forwarded by each node sender deletes its messages from the ring the common ring is the single point of failure (complicated connectors needed) Unidirectional traffic Slide 48: Ring Topology Hybrid Network Topology : Hybrid Network Topology No restrictions on how to link the nodes Topology can adapt to individual organization needs Slide 50: Hybrid Topology Slide 52: Simplex Ex: Keyboards and traditional monitors Slide 53: Half-Duplex Ex: Walkie-talkies & Citizen band radios Slide 54: Full-Duplex Ex: Telephone network Network Classification : Network Classification Classification of interconnected processors by scale. Slide 57: Network Types by Scope WAN wide area network cross large span of space (continental) typically heterogeneous and low speed example: Internet MAN metro-area network regional scope (city-wide) LAN local area network limited scope (a couple of buildings) typically homogeneous & high speed example: Ethernet & Token ring Local Area Networks : Local Area Networks Local area networks (LANs) are privately-owned networks within a single building or campus of up to a few kilometers in size. LANs are distinguished by three characteristics: (Restricted in) Size Transmission technology: 10 Mbps to 10 Gbps (1 Mbps = 1,000,000 bits/sec, 1 Gbps = 1,000,000,000 bits/sec). Topology: bus and ring Local Area Networks : Local Area Networks Two broadcast networks (a) Bus: Ethernet – IEEE 802.3 (b) Ring: IEEE 802.5, FDDI Slide 60: Local Area Network Slide 61: Local Area Network LAN Configurations : LAN Configurations Switched Switched Ethernet May be single or multiple switches ATM LAN Fibre Channel Wireless Mobility Ease of installation Metropolitan Area Networks : Metropolitan Area Networks A metropolitan Area Networks (MAN) is a network that interconnects users with computer resources in a geographic area or region such as a city. Deployment Cable television Wireless: IEEE 802.16 Metropolitan Area Networks : Metropolitan Area Networks MAN Middle ground between LAN and WAN Private or public network High speed Large area Metropolitan Area Networks : Metropolitan Area Networks A metropolitan area network based on cable TV. Slide 66: Metropolitan Area Network Wide Area Networks : Wide Area Networks A wide area network (WAN) spans a large geographical area, often a country and continent. It contains a collection of machines (hosts). The hosts are connected by a communication subnet. The subnet consists of two components: Transmission lines Switching elements: router Wide Area Networks : Wide Area Networks Relation between hosts on LANs and the subnet. Wide Area Networks : Wide Area Networks Large geographical area Crossing public rights of way Rely in part on common carrier circuits Alternative technologies Circuit switching Packet switching Frame relay Asynchronous Transfer Mode (ATM) Slide 70: Wide Area Network Internetworks : Internetworks Different networks are connected by means of machines called gateways. A collection of interconnected networks is called an internetwork or internet. A common form of internet is a collection of LANs connected by a WAN. Slide 72: Internetwork (Internet) NetworkingConfiguration : NetworkingConfiguration What’s the Internet: “nuts and bolts” view : What’s the Internet: “nuts and bolts” view millions of connected computing devices: hosts, end-systems PCs workstations, servers PDAs phones, toasters running network apps communication links fiber, copper, radio, satellite transmission rate = bandwidth routers: forward packets (chunks of data) “Cool” internet appliances : “Cool” internet appliances World’s smallest web server http://www-ccs.cs.umass.edu/~shri/iPic.html IP picture frame http://www.ceiva.com/ Web-enabled toaster+weather forecaster What’s the Internet: “nuts and bolts” view : What’s the Internet: “nuts and bolts” view protocols control sending, receiving of msgs e.g., TCP, IP, HTTP, FTP, PPP Internet: “network of networks” loosely hierarchical public Internet versus private intranet Internet standards RFC: Request for comments IETF: Internet Engineering Task Force local ISP company network regional ISP router workstation server mobile What’s the Internet: a service view : What’s the Internet: a service view communication infrastructure enables distributed applications: Web, email, games, e-commerce, database., voting, file (MP3) sharing communication services provided to apps: connectionless connection-oriented cyberspace [Gibson]: “a consensual hallucination experienced daily by billions of operators, in every nation, ...." Frame Relay : Frame Relay Packet switching systems have large overheads to compensate for errors Modern systems are more reliable Errors can be caught in end system Most overhead for error control is stripped out Asynchronous Transfer Mode : Asynchronous Transfer Mode ATM Evolution of frame relay Little overhead for error control Fixed packet (called cell) length Anything from 10Mbps to Gbps Constant data rate using packet switching technique Wireless Communication : Wireless Communication Wireless communication is not a new idea. Native American smoke signal Chinese Beacon fire Wireless telegraph using Morse Code Modern digital wireless systems have better performance, but the basic idea is the same. Wireless Networks : Wireless Networks Categories of wireless networks: System interconnection Wireless LANs Wireless WANs System Interconnection : System Interconnection System interconnection is all about interconnecting the components of a computer using short-range radio. Some companies got together to design a short-range wireless network called Bluetooth to these components. Bluetooth allows digital cameras, headsets, scanners, and other devices to connect to a computer in a short range. Bluetooth Standard : Bluetooth Standard The Bluetooth document is adopted by IEEE (Institute of Electrical and Electronics Engineers) 802.15 as a basis for wireless personal area networks. Work at 2.4 GHz Transfer up to 2 Mbps 10 meters range Wireless Networks : Wireless Networks (a) Bluetooth configuration (b) Wireless LAN Wireless LANS : Wireless LANS The wireless local area networks (LANs) are systems in which every computer has a radio modem and antenna with which it can communicate with other systems. Wireless LANs are common in small offices and homes. There is a standard for wireless LANs, called IEEE 802.11. Wireless WANS : Wireless WANS The wireless wide area networks (WANs) are systems used in the wide area. The radio network used for cellular telephones is an example of a low-bandwidth (low transfer rate) wireless system. First generation: analog for voice Second generation: digital for voice Third generation: digital for voice and data Wireless Networks : Wireless Networks (a) Individual mobile computers (b) A flying LAN Wireless WANS : Wireless WANS High-bandwidth wide area wireless networks are also being developed. A standard for it, called IEEE 802.16, has also been developed. Work at 10-to-66 GHz Transfer up to 155 Mbps 30 miles range Home Network Categories : Home Network Categories Computers (desktop PC, PDA, shared peripherals) Entertainment (TV, DVD, VCR, camera, stereo, MP3) Telecomm (telephone, cell phone, intercom, fax) Appliances (microwave, fridge, clock, furnace, air cooler) Telemetry (utility meter, burglar alarm, babycam). Home Network Properties : Home Network Properties The network and devices have to be easy to install. The network and devices have to be foolproof in operation. Low price is essential for success. The main application is likely to involve multimedia. It must be possible to start out with one or two devices and expand the reach of the network gradually. Security and reliability will be very important. A closer look at network structure : A closer look at network structure network edge: applications and hosts network core: routers network of networks access networks, physical media: communication links Circuit Switching : Circuit Switching Dedicated communications path established for the duration of the conversation e.g. telephone network Packet Switching : Packet Switching Data sent out of sequence Small chunks (packets) of data at a time Packets passed from node to node between source and destination Used for terminal to computer and computer to computer communications Data Communication Frameworks : Data Communication Frameworks Two major data communication frameworks have been developed to help ensure that networks meet business and communication requirements: Open Systems Interconnection (OSI) reference model developed by the International Standards Organization (ISO) Transmission Control Protocol/Internet Protocol (TCP/IP) suite Transmission Speeds : Transmission Speeds Important Standard-Setting Organizations : Important Standard-Setting Organizations Online System Requirements : Online System Requirements PERFORMANCE Response Time Throughput Consistency Flexibility Online Systems Requirements Continued : Online Systems Requirements Continued Availability Reliability Mean time between failure (MTBF) Mean time to repair (MTTR) Fault Tolerance Recovery Security Business Data Communication Applications : Business Data Communication Applications Major data communication applications include: E-mail Groupware Knowledge management systems E-commerce and e-business applications Wireless applications Groupware Applications : Groupware Applications Group calendar systems Electronic filing cabinets Project management software Group support systems Electronic meeting and videoconferencing systems Document management systems (image processing systems) Other Data Communication Applications : Other Data Communication Applications Batch applications Data entry applications Distributed applications Inquiry/response applications Interactive applications Sensor-based applications Combined applications Application Service Providers : Application Service Providers Many businesses have turned to third-party services for some or all of their business and data communications applications Application service providers (ASPs) are third-party organizations that manage and distribute software and services to other companies over the Web Many ASPs specialize in integrated e-commerce and e-business applications Business Data Communications Issues : Business Data Communications Issues Major data communications issues include: Cost-effectiveness The Internet Bandwidth Evolving technologies Convergence Standards Privacy and security Services versus Throughput Rates : Services versus Throughput Rates You do not have the permission to view this presentation. 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