* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Extended Learning Module C
Survey
Document related concepts
Internet protocol suite wikipedia , lookup
Deep packet inspection wikipedia , lookup
Network tap wikipedia , lookup
Airborne Networking wikipedia , lookup
Computer network wikipedia , lookup
Net neutrality law wikipedia , lookup
Recursive InterNetwork Architecture (RINA) wikipedia , lookup
Zero-configuration networking wikipedia , lookup
Policies promoting wireless broadband in the United States wikipedia , lookup
Wireless security wikipedia , lookup
IEEE 802.11 wikipedia , lookup
Cellular network wikipedia , lookup
Transcript
Chapter 6 Business Networks and Telecommunications Ch 6 Oz (5th ed) 1 Telecommunications and Networks Telecommunications concerns the movement of information between two devices over a distance Information includes data, audio, or video Networks are collections of devices (nodes) that can engage in telecommunications 2 The Value of Telecommunications in Business Telecommunications has improved business efficiency and effectiveness to the point that business cannot be conducted without telecommunications Advantages Better business communication Geographical distance irrelevant Faster communication/instant transaction Information becomes immediately available Better distribution of data Flexible and mobile workforce Alternative channels 3 Dominant Telecommunications Applications Cell phones (local and long distance calls, GPS, email, digital cameras) Video conferencing Fax Banking (ATMs and online) RFID in warehouse and wireless payments (gas pump) Peer-to-peer file sharing (Napster) Web-empowered commerce Buying and selling Training and education Research Marketing 4 The Current Business Environment for Large Firms The network infrastructure for a large corporation consists of three separate telecommunications systems Data (text, numbers, etc.) voice, video images. The environment is moving towards a common Internet foundation for all three (converged networks) 5 Corporate Networks Voice Data 6 Pieces in the Corporate Network Center piece is a collection of linked LANS that support a firm wide corporate network A series of servers supporting a corporate web site linked to enterprise and legacy systems (data) Support for a mobile sales force) (voice) Separate telephone network (cell and landline) (voice) Separate video conferencing system (not shown) (video) Currently no one vendor can supply all of the services required How does a manager navigate through this complex environment and make the right decisions? 7 Digital and Analog Signals Digital signals (1’s and 0’s) are represented by a discrete non-continuous wave form. Analog signals are represented by a sine curve . The human voice, music, and noise are examples of analog signals From a physical point of view, signals can be converted to an electric (carried over a wire) or electromagnetic (radio) signal In telecommunications there is a need to convert digital signals to analog signals and vice versa. Computers emit digital signals but parts of the telephone system only transmit analog signals, so digital signals must be converted into an analog signal and vice versa (need for your modem) 8 More on Signals All signals can be represented as a sine wave (curve). The amplitude of a sine wave is the maximum height of the sine wave from the x-axis The frequency of a sine wave is the number of times a sine wave makes a complete cycle within a given time frame. Cycles per second is referred to as Hertz (Hz) Digital data can be converted to a digital signal by using two different voltages. Digital data can be converted to an analog signal by using either two different frequencies or two different amplitudes. The greater the frequency of a signal, the higher the possible data transfer rate; the higher the desired data transfer rate, the greater the need signal frequency. Broadband (multiple signals) versus baseband (one signal) 9 Representation of Signals Figure 6.8 Signal modulation 10 Electromagnetic Frequency Spectrum (Radio Waves) ELF VLF 100 LF 1K MF 100K HF 1M1M VHF 10M UHF 100M Microwave 1G Optical Hertz 10G All waves behave similarly Frequency differences Amount of data Distance Interference / Noise 11 Electromagnetic Signals The electromagnetic spectrum can be expressed in terms of energy, wavelength, or frequency. Each way of thinking about the EM spectrum is related to the others in a precise mathematical way. 12 Transmission Speeds Digital signal speeds are usually expressed in bits per second (Kbps, Mbps, and Gbps). Analog signal speeds are usually expressed in frequency per second or Hertz (KHz, MHz, or GHz). A simple relationship between bps and frequency is found in Nyquist’s theorem C=2*f*(log2)*L where f is the frequency, L is the number of signal levels (often 2) and C is the capacity of the medium in bps The range of frequencies accommodated on a particular medium is called its bandwidth. For example, current cell phones operate in a bandwidth between 1.85 GHz and 2.2 GHz 13 Measures of Transmission Speeds 14 Multiplexing Concept A channel is a path followed by a flow of information (stream of bits). The information is carried by a digital or analog signal. Channels and bandwidth – cell phone example Multiplexing uses a single channel to carry simultaneous transmissions from multiple sources. Examples Frequency division multiplexing divides a high speed channel into multiple channels of slower speeds (FDMA – code division multiple access) Time division multiplexing assigns the sender transmitter a small slice of time to use the high speed channel (TDMA) Code division multiplexing assigns each user a special code enabling multiple users on a single channel (CDMA) 15 Transmission Media Wire mediums twisted pair coaxial cable fiber optic (each strand carries one signal) Next generation optical networks (multiple data streams over a single strand) Wireless transmissions are based on various types of electromagnetic waves (radio frequencies) terrestrial microwave satellite microwave (GEO) low-orbit satellites (LEO) Electrical power line (broadband over power lines – BPL) – Duke Energy will be doing this soon 16 Media Comparisons Figure 6.7 Characteristics of channel media 17 Transmission Speeds of Typical Mediums 18 A Simple Network 19 Basic Network Components A network consists of two or more connected computers. A network interface card (NIC) is the connection point between one computer and the network A network operating system (NOS) routes and manages communications on the network and coordinates network resources (saving or retrieving files on your hard drive versus a network drive) 20 Basic Network Components (continued) Hubs connect network components, sending a packet of data to all other connected devices A switch has more intelligence than a hub and can forward data to a specified device. The switch is used within a given network to move information. Unlike a switch, a router (or bridge) is a special communications processor used to route packets of data through different networks, ensuring that the message sent gets to the correct address. A router connects a LAN to the Internet. Modems are used to convert digital signals to analog signals and vice versa 21 Types of Networks Geographic scope LANs (wired and wireless) MANs WANs and VANs PANs (special type of LAN) VPN (virtual private networks) Role of server Client-server networks Peer-to-peer networks 22 Local Networks: LANs Local area network - a network that requires its own cabling and encompasses a limited distance (one or two buildings); nodes are usually PCs and peripherals Advantages handle high volumes of data sharing of hardware, software, files, and data unique application (email, video conferencing, on-line applications) Disadvantages expandability vendor support or internal expertise 23 Wireless LANS Benefits Easier installation Lower initial cost; lower operational costs Easily expanded (scalability) Main drawback is security Compared to wired networks wireless networks are less secure Security measures exist but are not as easy to set up as in wired; tend to slow down transmission 24 Large Networks: WAN Wide area networks nodes Corporations can build their own using communications service providers Switched and dedicated lines Individual firm assumes significant role in telecommunications management 25 Large Networks: VANs Value-added networks are private data-only networks that provide economies in service cost and network management because they are used by many firms. Many also provide Internet access. Value-added means customers do not have to invest in network equipment and management Disadvantage loss of control/expertise Security Tymnet, SprintNet, and General Electric provide VAN services An example of a Web based EDI product 26 Other Networks Metropolitan area network (MAN) links multiple LANs within a large city Personal area network (PAN) wireless network designed for handheld and portable devices Used by one or two people Transmission speed slower Maximum distance 10 meters A virtual private network (VPN) enables companies to link their LANS to the Internet and protect the LAN from unwanted intruders. Used in the construction of intranets and extranets 27 Client/Server and Peer-to-Peer Networks The hardware side The client The server The software side Client/server software splits the processing of applications between the client and server to take advantage of strengths of each machine E-mail and browsers are examples Client/server computing has largely replaced centralized mainframe computing Peer-to-peer networks there is no central device that controls communication (Napster) 28 Switching Techniques In packet-switched networks, messages are first broken down into small bundles of data called packets that are sent along different communication paths and reassembled once they reach their destinations. More efficient use of the network’s capacity Packets include addressing information and ways to check transmission errors along with the data. Always done on the Internet, but restricted to data now being used for voice (VoIP) Circuit switching creates a dedicated path between points in a network. For the duration of the communication no other transmissions may use this circuit and all transmissions follow a dedicated path. The telephone system links together media segments to create a single unbroken circuit for each telephone call. Not very efficient for large volumes of data 29 Protocols Protocols are rules and procedures (virtually languages) that govern the transmissions between components (devices) in a single network or between two networks Important protocols TCP/IP (Internet protocols) HTTP (Internet protocol) Ethernet is the most popular protocol for wired LANs Important wireless protocols Wi-Fi Bluetooth WiMax 30 TCP/IP TCP/IP is the communications protocol used by the Internet and all Internet devices. TCP part Handles the movement of data between computers Establishes a connection between the computers, sequences the transfer of packets, and acknowledges the packets sent IP part Responsible for the delivery of packets Includes the disassembling and reassembling of packets during transmission Defines the numeric addressing scheme; 4 bytes in length; 232 potential addresses 31 More on TCP/IP Adoption by the world of TCP/IP as a standard protocol is a major factor in the success of the Internet Other terms associated with the Internet and TCP/IP Host and backbone IP number (static and dynamic) Domain Name System (DNS) 32 Internet Protocol Numbers (IPv4) Each device attached to the Internet has an IP number (some static/some dynamic) Each IP number consists of four parts separated by periods. Each part contains a number between 0 and 255 therefore each part can be represented by 8 bits or 32 bits for the entire IP number (e.g., 146.186.87.220). Approximate number of devices able to be on the Internet is 232 or 210* 210* 210*22~103*103*103*22=109*4 (4 billion) The process of associating an IP number with a character based name is called domain name resolution. The domain name system (DNS) is the software that associates character based names with the IP number. Internet Service Providers (ISPs) usually dedicate a server to perform domain name resolution (i.e., a DNS server). To determine speed of your connection: http://www.ipadress.com/speedtest/ To determine your IP number: http://www.What ismyIpaddress.com 33 Wireless Network Protocols Wireless technologies are of interest to business because they eliminate the need for expensive cables and enable mobility Wireless protocols (or Wi-Fi) apply to mobile devices (e.g., laptops or PDA) Family of standards IEEE 802.11 (the 11 stands for the max bit rate supported, 11 Mpbs) Most popular is 802.11g which operates in the 2.4-2.5 GHz range Transmission range is about 300 ft (distance is likely to increase) To make a device wireless requires the device to contain a wireless card 34 Access Points and Hot Spots In order to communicate with a network using a wireless device, you must be close enough to an access point (AP). The access point is a device that is connected to a wired network. If a household has a wired connection to the Internet (cable or DSL) then wireless devices can access the Internet by acquiring a wireless router (an AP) that is connected to your cable or DSL modem. This enables all your wireless devices to link to the Internet. Public access points are often called hotspots. Winthrop has several hotspots on campus Cell phones with dual circuitry can communicate with hot spots 35 Wireless Issues Plus side Mobility and low installation cost Can be extended by adding access points Newer protocols in the 802.11 family offer security protocols (WEP, WPA, and WPA2) Down side Interference from other devices The Wi-Fi standard (802.11g is replacing 802.11b) is easily penetrated by outsiders with appropriate hardware and software Competing standards (protocols); Bluetooth is another wireless networking standard for creating small private networks (range of 30 meters) 36 Wireless Applications Use of wireless devices in warehouses Airlines are equipping their planes with Wi-Fi circuitry so passengers can connect to the Internet in flight Utility companies have installed meters that can send signals to the utility company indicating customer usage Equipping electronic devices such as cell phones, digital cameras, game consoles, digital camcorders with Wi-Fi circuitry eliminates need for a physical connection. 37 WiMAX Protocol WiMAX (IEEE 802.16) Increases range and speed of Wi-Fi to 8-10 miles and 100 Mbps Enables an entire city to become a hotspot Provide low-cost Internet service to masses No need for telephone companies A nationwide network could be built for less than $3 billion 38 How Wi-MAX Works 39 Mobile Broadband Wireless Access (MBWA or IEEE 802.20) This protocol will enable cell phones to use cell phone towers to get VoIP and access Internet resources Similarly a laptop with a special MBWA card will be able to act as a cell phone A device that employs this protocol will be able to do everything you currently do with a telephone through the Internet (Web browsing, file transfer, e-mail, VoIP video telephony, videoconferencing, audio streaming, Web –based gaming, and file sharing). Protocol will be compatible with Wi-fi and Bluetooth protocols Protocol will have high levels of security An example from Sprint (http://www.sprint.com/business/products/phones/usbU720_all PcsPhones.html ) 40 Protocol Summary Protocol Usage Frequency Range Wide variety Speed TCP/IP Internet Wide variety Ethernet Wired LANs IEEE 802.11b and g (Wi-Fi) Wireless LANs 2.4-2.5 GHz Up to 54 Mbps Bluetooth (IEEE 802.15) Wireless PANs 2.4-2.5 GHz 1 Mbps Wi-Max (IEEE 802.16) Wireless MANs 2-11 GHz Up to 100 Mbps CDMA and GSM Cell phones Up to 3 GHz Up to 144 Kbps MBWA (IEEE 802.20) Mobile broadband wireless access < 3.5 GHz 4 Mbps EV-DO Mobile broadband Internet access over a cellular network Up to 10 Gbps 2.4 Mbps 41 Generations of Mobile Communication (cell phones) First generation (1 G) Analog signals with circuit switching Second generation (2 G) Use of multiplexing Converted voice to digital signals Faster than 1 G Third generation (2.5 G) Speeds up to 144Kbps Limited Internet access Packet switching Fourth generation (3G) Speeds up to 1 Mbps Support for video conferencing Full Internet access Similar to Wi-Fi but more expensive; Wi-Fi inside – 3G outside Fifth generation (4G) Speeds up to 100 Mbps Multitasking (listen to music; access Internet; and make calls) 42 Internet Networking Services Variety of options to choose from when subscribing to network services Downstream: speed of receiving from network Upstream: speed of transmitting to network 43 Internet Networking Services (continued) Figure 6.6: Wireless networking protocols 44 Internet Networking Services: Cable and Digital Subscriber Lines (DSL) Cable Internet links provided by television cable firms At residence, cable split into TV set and computer; cable modem Cable line into a neighborhood is shared by all subscribers DSL Data remains digital through entire transmission Uses telephone lines connected to DSL bridge Asymmetric versus symmetric DSL Transmission rates related to distance from telephone company 45 Internet Networking Services: T1 and T3 Lines and Satellite T1 and T3 lines Point-to-point dedicated digital circuits T3 lines made of 24 channels of 64 Kbps T1 line made of 672 channels of 64 Kbps Expensive; not for individual consumers Satellite (useful in areas that lack DSL or cable) Service use microwaves Service provider installs dish antenna, used as communications satellite Speeds up to 45 Mbps GPS free satellite service Uses fixed or mobile antennas 46 Internet Networking Services: Fixed Wireless and Optical Carrier Fixed wireless Point-to-point transmission between two stationary devices; requires microwave transceivers on rooftop Wireless Internet service provider (WISP) Highly modular and scalable Optical Carrier (OC) Expensive but high connection speeds Uses basic unit of 51.84 Mbps Used by ISPs, search engines, and content-rich Web sites Broadband over Power Lines (BPL) Uses electric power lines to carry digital signals Even if subscriber revenue is low there are advantages to utility companies; monitor power consumption, detect power failure, track power outages 47 Future of Networking Technologies Broadband telephoning Radio Frequency Identification Convergence of technologies 48 Voice over Internet Protocol (VoIP) Uses Internet connection to conduct telephone conversations Can be done with special software or pay firms that specialize in the service (Vonnage) Possible ways to VoIP (PC to PC, PC-to-telephone, or telephone-to-telephone) For business users there are significant savings For individual consumer Often you don’t have 911 No phone when power is out since VoIP requires an electric modem Future is with advanced cell phones that support VoIP; big reduction in cell phone costs 49 Radio Frequency ID (RFID) RFID tags consist of a microprocessor and an antenna. Some tags can transmit on their own; others transmit through activation by a reader sending a signal to the chip History Technology was invented in 1934 Many different kinds of tags with many different capabilities such as range, storage capacity, alterability of data RFID tag of primary interest are the EPC (electronic product code) chips Designed to replace UPC codes 96-bit storage capacity; potential to give individual items a unique identifier; operate in 868-965 MHz Signals can only be read if within a few feet of reader Cost of tags is still high 5-10 cents per tag; limited to large ticket items 50 RFID Tags (Continued) Major applications of EPC chips (current and future) Track and locate inventory Track items as they move through a firm’s supply chain Smart shelves Privacy issues (EPC tags) Notification of the presence of a tag Killing the tag before you leave the store Restrictions on the use of tag generated data 51 Current Uses of RFID 52 Future Uses of RFID 53 Convergence of Technologies Convergence implies one device or one network doing multiple tasks Cell phones will double as Internet phones using VoIP Television sets will be able to function as regular TV and connect to the Internet concurrently PDAs soon will function as a TV and phone concurrently Portable music players (e.g., IPods) can use Wi-Fi to communicate with other Wi-Fi devices Local radio stations can use WiMax for digital radio; you will be able to download songs you have listened to and play them back 54