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Network+ Guide to Networks 6 th Edition

Network+ Guide to Networks 6 th Edition. Chapter 12 Voice and Video Over IP. Objectives. Use terminology specific to converged networks Explain VoIP (Voice over IP) services, PBXs, and their user interfaces Explain video-over-IP services and their user interfaces

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Network+ Guide to Networks 6 th Edition

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  1. Network+ Guide to Networks6th Edition Chapter 12 Voice and Video Over IP

  2. Objectives • Use terminology specific to converged networks • Explain VoIP (Voice over IP) services, PBXs, and their user interfaces • Explain video-over-IP services and their user interfaces • Describe VoIP and video-over-IP signaling and transport protocols, including SIP, H.323, and RTP • Understand QoS (quality of service) assurance methods critical to converged networks, including RSVP and DiffServ Network+ Guide to Networks, 6th Edition

  3. Terminology • IP telephony (VoIP) • Any network carrying voice signals using TCP/IP • Public or private • Runs over any packet-switched network • Virtually any data connection type can carry VoIP signals, including: • T-carriers, ISDN, DSL, broadband cable, satellite connections, WiFi, WiMAX, HSPA+, LTE, cellular telephone networks Network+ Guide to Networks, 6th Edition

  4. Terminology (cont’d.) • Internet telephony • VoIP calls carried over Internet Network+ Guide to Networks, 6th Edition

  5. Terminology (cont’d.) • Nondata applications on converged networks • IPTV (IP television) • Videoconferencing • Multiple participants communicate and collaborate via audiovisual means • Streaming video • Compressed video delivered in continuous stream • Webcasts • Streaming videos supplied via the Web Network+ Guide to Networks, 6th Edition

  6. Terminology (cont’d.) • Multicasting • One node transmits same content to every client in group • Video over IP Services: • IPTV, videoconferencing, streaming video, & IP multicasting • Unified communications (unified messaging) service • Several communication forms available from single user interface • Users can access the Web, send & receive faxes, email messages, instant messages, or telephone calls, and participate in videoconference calls—all from one console Network+ Guide to Networks, 6th Edition

  7. VoIP Applications and Interfaces • Reasons for implementing VoIP • Lower voice call cost (toll bypass) • New, enhanced features and applications • Centralize voice and data network management • Voice & data can be combined on a network in several configurations: • Use traditional telephone (sends, receives analog signals) • Use telephone specially designed for TCP/IP transmission • Use a computer with microphone, speaker, VoIP client software • Mixture of these types Network+ Guide to Networks, 6th Edition

  8. Analog Telephones • Traditional telephone used for VoIP • Signals converted to digital form • Codec (coder/decoder) • Method of compressing, encoding, analog signals into bits Network+ Guide to Networks, 6th Edition

  9. Analog Telephones, cont. • Analog VoIP clients may connect to IP networks in one of four ways: • Firstanalog-to-digital conversion method: • ATA (analog telephone adapter) • Card within computer workstation • Or externally attached device • Telephone line connects to RJ-11 adapter port • Converts analog voice signals to IP packets Network+ Guide to Networks, 6th Edition

  10. Figure 12-1 ATA (analog telephone adapter) Courtesy of Grandstream Networks, Inc. Network+ Guide to Networks, 6th Edition

  11. Analog Telephones (cont’d.) • Second analog-to-digital conversion method: • Connecting an analog telephone line to VoIP-enabled device (switch, router, gateway) • Convert analog voice signals into packets and then issuing the packets to a data network—and vice versa Network+ Guide to Networks, 6th Edition

  12. Figure 12-2 VoIP router Photo of SmartNode™4520 Analog VoIP router from Patton Electronics , Co. Network+ Guide to Networks, 6th Edition

  13. Analog Telephones (cont’d.) • Third analog-to-digital conversion method: • Digital PBX (a.k.a IP-PBX) • PBX (private branch exchange): telephone switch connecting calls within private organization • IP-PBX • Is a private switch • Accepts, interprets both analog & digital voice signals • Connects with traditional PSTN lines, data networks • Transmits, receives IP-based voice signals to and from other network connectivity devices • Most are packaged with sophisticated software used to configure and maintain an organization’s phone system Network+ Guide to Networks, 6th Edition

  14. Figure 12-3 IP-PBX Courtesy of Epygi Technologies, Ltd. Network+ Guide to Networks, 6th Edition

  15. Analog Telephones (cont’d.) • Hosted PBX • Exists on the Internet • Separate provider for call management services • May also be called virtual PBXs • Trademark of VirtualPBX company • Advantage of Hosted PBXs • No installation or maintenance of hardware and software for call completion and management • VoIP Trunk • ONSIP example of a VoIP trunk provider Network+ Guide to Networks, 6th Edition

  16. Analog Telephones (cont’d.) • Fourth analog-to-digital conversion method: • Traditional telephone connects to analog PBX • Then connects to voice-data gateway • Gateway connects traditional telephone circuits with TCP/IP network • Internet or private WAN • The Gateway • Digitizes incoming analog voice signal • Compresses data • Assembles data into packets • Issues packets to packet-switched network Network+ Guide to Networks, 6th Edition

  17. Figure 12-4 Integrating VoIP networks and analog telephones Courtesy of Course Technology/Cengage Learning Network+ Guide to Networks, 6th Edition

  18. IP Telephones • IP telephones (IP phones) • Transmit, receive only digital signals • Voice immediately digitized, issued to network in packet form • Requires unique IP address • Looks like traditional touch-tone phone • Connects to RJ-45 wall jack • Connection may pass through connectivity device before reaching IP-PBX Network+ Guide to Networks, 6th Edition

  19. Figure 12-5 Accessing a VoIP network from IP phones Courtesy of Course Technology/Cengage Learning Network+ Guide to Networks, 6th Edition

  20. IP Telephones (cont’d.) • IP telephone features • Speed-dialing • Call hold • Transfer, forward • Conference calling • Voice-mail access • Speakers, microphones, LCD screen • Mobile and wired styles • Some can act as Web browsers • Easily moved from office to office Network+ Guide to Networks, 6th Edition

  21. IP Telephones (cont’d.) • Conventional analog telephone • Obtains current from local loop • Current used for signaling (ring, dial tone) • IP telephones • Need electric current • Not directly connected to local loop • Most use separate power supply • Susceptible to power outages • Requires assured backup power sources • Some use PoE (power over Ethernet) Network+ Guide to Networks, 6th Edition

  22. Figure 12-6 An IP phone Courtesy of Grandstream Networks, Inc. Network+ Guide to Networks, 6th Edition

  23. Softphones • Computer programmed to act like IP telephone • Provide same calling functions • Connect to network; deliver services differently • Prerequisites • Computer minimum hardware requirements • IP telephony client installed • Digital telephone switch communication • Full-duplex sound card • Microphone, speakers • Softphone example: Skype is a popular Internet proprietary telephony software and is a type of softphone Network+ Guide to Networks, 6th Edition

  24. Softphones (cont’d.) • Graphical interface • Presented after user starts softphone client software • Customizable • Versatile connectivity • VoIP solution for traveling employees and telecommuters • Convenient, localized call management • Call tracking • Date, time, duration, originating number, caller names • Simplifies recordkeeping and billing Network+ Guide to Networks, 6th Edition

  25. Figure 12-7 Softphone interface Courtesy of CounterPath Corporation Network+ Guide to Networks, 6th Edition

  26. Figure 12-8 Connecting softphones to a converged network Courtesy of Course Technology/Cengage Learning Network+ Guide to Networks, 6th Edition

  27. Video-over-IP Applications and Interfaces • Cisco Systems estimate • By 2015, over two-thirds of Internet traffic will be video traffic • Factors fueling growth • Large quantity of video content available (Netflix & Hulu) • Increasing number of devices accessing Internet • Decreasing cost of bandwidth, equipment • Video-over-IP services categories • Streaming video, IPTV, videoconferencing Network+ Guide to Networks, 6th Edition

  28. Streaming Video • Is a video-over-IP application • Basic computer appropriate audiovisual hardware and software to view the encoded video • One method is Video-on-demand: • Files stored on video streaming server • Popular • Viewer chooses video when convenient: Web browser • Another method is Streaming video: • Video issued live • Directly: source to user Network+ Guide to Networks, 6th Edition

  29. Streaming Video (cont’d.) • Drawbacks of live stream • Content may not be edited before distribution • Viewers must connect with stream when issued • Video-on-demand benefits • Content viewed at user’s convenience • Viewers control viewing experience • Pause, rewind, fast-forward capabilities Network+ Guide to Networks, 6th Edition

  30. Figure 12-9 Video-on-demand and live streaming video Courtesy of Course Technology/Cengage Learning Network+ Guide to Networks, 6th Edition

  31. Streaming Video (cont’d.) • Most streaming video • Takes place over public networks Network+ Guide to Networks, 6th Edition

  32. IPTV (IP Television) • Telecommunications carrier and cable company networks • Offer high-bandwidth Internet connections to deliver digital television signals using IPTV • Elements of delivering digital video to consumers • Telco accepts video content at a head end • Telco’s CO (central office) servers provide management services • Video channel assigned to multicast group • When an IPTV user changes the channel they are opting out of one IP multicast group and opting into another Network+ Guide to Networks, 6th Edition

  33. Figure 12-10 A telecommunications carrier’s IPTV network Courtesy of Course Technology/Cengage Learning Network+ Guide to Networks, 6th Edition

  34. Videoconferencing • Videoconferencing • Full-duplex connections • Participants send and receive audiovisual signals • Real time • Benefits • Cost savings, convenience • Replace face-to-face business meetings • Allow collaboration Network+ Guide to Networks, 6th Edition

  35. Videoconferencing (cont’d.) • Videoconferencing uses • Telemedicine • Tele-education • Judicial proceedings • Surveillance • Hardware, software requirements • Means to generate, send, receive audiovisual signals • Computer workstation with cameras, microphones, software • Video terminal or video phone Network+ Guide to Networks, 6th Edition

  36. Figure 12-12 Videophone Courtesy of Grandstream Networks Network+ Guide to Networks, 6th Edition

  37. Videoconferencing (cont’d.) • Video bridge • Manages multiple audiovisual sessions so that participants can see and hear each other • May exist as a piece of Hardware or software, in the form of a conference server • Internet-accessible video bridging services can be leased • Well suited for occasional videoconference use • Some organizations might maintain their own conference servers Network+ Guide to Networks, 6th Edition

  38. Signaling Protocols • Signaling protocols: • Set up and manage sessions between clients • Early VoIP: used proprietary signaling protocols • Today: standardized signaling protocols are usually used which are discussed next • SS7 (Signaling System 7): typically handles call signaling on the PSTN • May come up when trying to interconnect the PSTN with VoIP Network+ Guide to Networks, 6th Edition

  39. H.323 • Describes architecture & a group of protocols for: • Establishing and managing packet-switched network multimedia sessions • Supports voice and video-over-IP services • Terms: • H.323 terminal (IP phone) • H.323 gateway (connects to other signaling protocols) • H.323 gatekeeper (authenticates terminals, manages bandwidth, and oversees call routing, accounting, and billing • MCU (multipoint control unit) provides support for multiple H.323 terminals • H.323 zone (collection of H.323 terminals, gateways, and MCUs are managed by a single H.323 gatekeeper) Network+ Guide to Networks, 6th Edition

  40. Figure 12-13 An H.323 zone Courtesy of Course Technology/Cengage Learning Network+ Guide to Networks, 6th Edition

  41. H.323 (cont’d.) • H.225 and H.245 signaling protocols • Specified in H.323 standard • Operate at Session layer of OSI • H.225 handles call or videoconference signaling • IP telephone requests a call setup via H.225 • H.245 ensures correct information type formatting—whether voice or video issued so that the H.323 terminal can interpret the data • H.323 remains a popular signaling protocol on large voice and video networks • In sum, H.323 is the call control signaling protocol • Used to setup, maintain, teardown, and redirect calls Network+ Guide to Networks, 6th Edition

  42. SIP (Session Initiation Protocol) • Performs similar functions as H.323 • Application layer signaling and control protocol that was modeled after HTTP • VoIP call is formatted like an HTTP request and rely on URL style addresses • Limited capabilities compared to H.323 • SIP does not have features such as caller ID and instead it depends on other protocols and services to supply them Network+ Guide to Networks, 6th Edition

  43. SIP (cont’d.) • SIP network components (pg. 574): • User agent • User agent client • User agent server • Registrar server • Proxy server • Redirect server Network+ Guide to Networks, 6th Edition

  44. Figure 12-14 An H.323 zone Courtesy of Course Technology/Cengage Learning Network+ Guide to Networks, 6th Edition

  45. SIP (cont’d.) • Some VoIP vendors prefer SIP over H.323 • Simplicity—easier to setup • Fewer instructions to control call • Consumes fewer processing resources than H.323 • SIP and H.323 • Regulate call signaling and control for VoIP or video-over-IP clients and servers • Do not account for communication between media gateways • MGCP or MEGACO protocols are used for communication between media gateways Network+ Guide to Networks, 6th Edition

  46. MGCP (Media Gateway Control Protocol) and MEGACO (H.248) • Media Gateway: A gateway capable of accepting connections from multiple devices, such as IP telephones, traditional telephones, IP fax machines, traditional fax machines, and translating analog signals into packets and vice versa • Accepts PSTN lines, converts signals into VoIP format, and translates between signaling protocols • Gateways still need to exchange and translate signaling and control information with each other so that voice and video packets are properly routed through the network • They rely on the MGC (media gateway controller) device, which can manage multiple media gateways Network+ Guide to Networks, 6th Edition

  47. MGCP and MEGACO (cont’d.) • MGC (media gateway controller) • Used by media gateways to make sure that voice and video packets are properly routed through the network • Enables multiple media gateways to communicate • Computer managing multiple media gateways • Also called a softswitch (software performs the call switching) Network+ Guide to Networks, 6th Edition

  48. MGC (media gateway controller) • Example: • When a media gateway receives a call, rather than attempting to determine how to handle the call, the gateway contacts the MGC with a message that says, “I received a signal. You figure out what to do with it next.” • The MGC then determines which of the network’s media gateways should translate the information carried by the signal. It also figures out which physical media the call should be routed over • Media gateways simply follow orders from the MGC Network+ Guide to Networks, 5th Edition

  49. MGCP and MEGACO (cont’d.) • MGC communicate with media gateways according to several protocols (MGCP or MEGACO) • MGCP (Media Gateway Control Protocol) • Commonly used on networks that support a number of media gateways • Can operate with both H.323 or SIP call signaling and control protocols • Older protocol • Newer gateway control protocol is MEGACO Network+ Guide to Networks, 5th Edition

  50. MGCP and MEGACO (cont’d.) • MGC gateway communicate protocols (cont’d.) • MEGACO (H.248) • Is a newer gateway control protocol • Performs same functions as MGCP • Different commands and processes • Operates with H.323 or SIP • Superior to MGCP Network+ Guide to Networks, 6th Edition

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