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Convergence Technologies

Convergence Technologies. Lesson 1: Convergence Industry Standards and Protocols. Objectives. Discuss the various standards agencies in the telecommunications industry Discuss the major industry standards in convergence technologies Identify and define the various IEEE 802 protocols

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Convergence Technologies

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  1. Convergence Technologies

  2. Lesson 1:Convergence Industry Standards and Protocols

  3. Objectives • Discuss the various standards agencies in the telecommunications industry • Discuss the major industry standards in convergence technologies • Identify and define the various IEEE 802 protocols • Identify and define the various ITU protocols • Discuss Requests for Comments (RFCs) used in convergence technologies

  4. Defining Convergence • Convergence– The integration of telephony and data technologies • Benefits of convergence: • Deliver services to any IP-enabled device • Allow for a more flexible use of data • Enable toll-free calling • Handle voice calls for multimedia communication • Enable the use of PCs as phones • Use existing infrastructure • Lower ownership costs

  5. Common VoIP Applications • Toll bypass • Fax over the Internet • PC phone to PC phone • IP-based public phone service • Call-center IP telephony • IP local line doubling

  6. Common VoIP Protocols • Session Initiation Protocol (SIP) • Initiates and manages sessions between two or more participants • Defines how end devices create, modify and terminate a connection • H.323 • Manages setup, tear down and call control • Defines components in a conferencing network • MGCP and Megaco/H.248 • A standard protocol for handling signaling and session management during a multimedia conference or VoIP call • Megaco is the IETF name for MGCP • H.248 is the ITU-T name for MGCP

  7. Governing Organizations in Convergence Technologies • IEEE – a nonprofit association based in the U.S. concerned with data communication standards • ITU – an agency within the UN that coordinates the establishment and operation of global telecommunication networks and services • IETF – an international community of operators, vendors, network designers and researchers concerned with the evolution of Internet architecture and the operation of the Internet • EIA – a U.S. electronics manufacturer organization that has published a number of standards related to telecommunication and computer communication • TIA – vendors, service providers and organizations involved in all aspects of modern communication networks • ANSI – an organization that defines coding standards and signaling schemes in the U.S. • Telcordia – provides engineering, administrative, software and telecommunications consulting services to telecommunications companies

  8. 802.1 – Internetwork 802.2 – Logical Link Control (LLC) 802.3 – CSMA/CD and Ethernet 802.5 – Token Ring Networks 802.6 – Metropolitan Area Networks Switched Multimegabit Data Service (SMDS) 802.9 – Integrated Data and Voice Networks 802.11 – Wireless LANs 802.12 – 100VG-AnyLAN 802.14 – Cable Modem Institute of Electrical and Electronics Engineers (IEEE) • IEEE 802 protocols – define the relationships between physical network interfaces and all signaling

  9. InternationalTelecommunication Union (ITU) • ITU H-Series protocols – define the structure and use of protocols for audiovisual and multimedia systems • H.225 • H.235 • H.245 • H.248 (Megaco) • H.261 • H.263 • H.323 • H.450

  10. InternationalTelecommunication Union (ITU)(cont'd) • ITU G-Series protocols – identify the data rate of VoIP connections in the network • G.711 – Toll Quality • G.723.1 • G.726 • G.728 • G.729

  11. InternationalTelecommunication Union (ITU)(cont'd) • ITU T-Series protocols – discuss different types of terminals for telephony services • T.30 • T.37 • T.38 • T.134

  12. InternationalTelecommunication Union (ITU)(cont'd) • ITU Q-Series protocols – address issues of switching and signaling • Q.931 • ITU X-Series protocols – address issues related to data networks and open system communication • X.200 • X.300 • Global System for Mobile Communications (GSM) • Wireless network system used primarily in Europe

  13. VoIP and Interoperability • International Multimedia Teleconferencing Consortium (IMTC) ensures that VoIP gateways and PC-based phones follow the same standards • VoIP Forum – subgroup of the IMTC • Created the VoIP Interoperability Implementation Agreement • A precursor to a standard that has formed the basis of subsequent standards • Widely supported in the industry

  14. Internet Engineering Task Force (IETF) • IETF Requests for Comments (RFCs) • RFC 3261 – Session Initiation Protocol (SIP) • RFC 3550 – RTP: A Transport Protocol for Real Time Applications • RFC 2205 – Resource Reservation Protocol • RFC 2750 • RFC 3936 • RFC 3802 – Toll-Quality Voice 32 Kbps ADPCM Registration • RFC 2805 – Media Gateway Control Protocol Architecture and Requirements • RFC 3494 – Lightweight Directory Access Protocol • RFCs 2236 and 3376 – Internet Group Management Protocol (IGMP)

  15. ElectronicIndustries Alliance (EIA) EIA TIA Commercial Building Telecommunications Wiring Standards

  16. Telecommunications Industry Association (TIA) • TIA/EIA standards • TIA/EIA – 810-A Telecommunications • TIA/EIA/IS – 811 Telecommunications

  17. American NationalStandards Institute (ANSI) • ANSI standards • T1.240 – Generic Network Information Model for Interfaces Between Operation Systems and Network Elements • T1.520 – Internet Protocol (IP) Data Communication Service – IP Packet Transfer and Availability Performance Parameters

  18. Telcordia(Formerly Bellcore) • Telcordia Generic Requirements standards • GR-301 – Public Packet Switched Network • GR-303 – Integrated Digital Loop Carrier System • GR-1504 – Wireless Service Provider Automatic Message Accounting • GR-3058 – Voice over Packet: Next Generation Networks (NGN) Accounting Management • GR-2804 – Universal Network to Server Access Method (UNAM) • Radio Free Ethernet (RFE)

  19. Summary • Discuss the various standards agencies in the telecommunications industry • Discuss the major industry standards in convergence technologies • Identify and define the various IEEE 802 protocols • Identify and define the various ITU protocols • Discuss Requests for Comments (RFCs) used in convergence technologies

  20. Lesson 2:Enabling Voice over IP (VoIP)

  21. Objectives • Discuss the functions of gatekeepers • Discuss the functions of gateways • Define delay, latency, jitter and wander, and identify their impact on real-time communications • Identify the importance of a jitter buffer • Identify the impact of large data frames onreal-time communications • Recognize the need for Quality of Service (QoS) for converged networks • Identify QoS technologies for converged networks

  22. Objectives (cont'd) • Identify common codecs and their bandwidth requirements in a converged environment • Describe the impact of compressing voice in a network • Compare and contrast the use of T1, E1 and J1 trunks for data and voice • Identify the factors that affect the bandwidth of packetized voice • Identify requirements for transporting modem and fax transmissions through a converged solution

  23. Investigating VoIP • Asynchronous transfer mode (ATM) – a connection-oriented technology that supports real-time video, voice and data for LANs and WANs • Frame relay – a packet-switching technology that supports data and voice for LANs and WANs • Comparing VoIP and standard PSTN connections

  24. Investigating Gatekeepers and Gateways • Gatekeeper functionality: • Admission control • Address translation • Bandwidth control • Zone management • Call control for point-to-point conferences • Codec translation • Call authorization • Bandwidth and call management • Accounting and billing • Call routing • Multipoint control unit (MCU) – required whenever three or more H.323 terminals are connected

  25. Gateway Functionality and Types • Gateways connect two different networks • Gateway types: • Signaling gateway – translates call control and administrative signals present on the circuit-switched PSTN into either SIP or H.323 • Media gateway – packetizes telephony information for transmission across the Internet or an intranet VoIP gateways

  26. To use a gatekeeper, you must register your VoIP terminal To register, a client must configure the terminal to search for and register with the gatekeeper Registering with a Gatekeeper

  27. Troubleshooting VoIP • VoIP variables – conditions that cause problems in voice communications • VoIP variables include: • Delay – the amount of wait time between the time a signal is sent and received • Latency – the amount of time required for data to be transmitted across a network • Jitter – variability in the arrival rate of data packets transmitted over a network • Wander – variability of more than one second in the arrival rate of data packets transmitted over a network (long-term jitter)

  28. Delay • Fixed delays • Propagation delay – caused by the distance between the request and the server fulfilling the request • Serialization delay – the time required to physically place voice call bits on a trunk line • End point processing delay – caused by compressing/decompressing and encoding/decoding data • Packetization delay – the time required to place digital traffic into a particular medium • Variable delays • Queuing delay – the time packets wait for other packets to be placed onto a trunk line • Router processing delay – the time required for a router to apply QoS settings, or to process packets that have arrived out of order

  29. Latency • Latency results when multiple delays occur • The most significant source of latency is the digital signal processing that occurs in gateways and routers • Relationship of perceived connection quality to one-way latency experienced in the connection: • Excellent 0 to 150 ms • Good 150 to 300 ms • Acceptable 300 to 450 ms • Unacceptable 450 ms or greater

  30. Jitter • Jitter occurs when packets in a voice transmission take different paths over a network, causing them to arrive out of sequence • A jitter buffer can correct this variability by providing a space in memory that allows packet resequencing

  31. Wander • Wander is due to synchronization problems in the network clocks used to control transmissions • When wander is detected, the signal must be reclocked, or synchronized, at the next network element to avoid propagating the wander activity • The Network Time Protocol (NTP) ensures that systems are accurate to within milliseconds • NTP servers belong to two strata: • Stratum 1 – clocks that are the most accurate • Stratum 2 – clocks that receive timing information from stratum 1 servers

  32. Large Data Frames and Delay Budgets • Frame – in VoIP, voice information embedded inside a UDP or TCP packet • Multiple voice frames can be compressed into a single packet • Compression: • Improves bandwidth efficiency • Increases latency • Compression techniques: • G.723 standard • G.729 standard • G.711 standard

  33. Calculating a Delay Budget • If data packets are too large, a sudden burst of calls may exceed the bandwidth you have allocated • To protect against this problem, you must create a delay budget to determine: • The type of data placed on the network • The number of trunks in use • The average number of calls, and amount of bandwidth and line numbers required • The peak number of calls

  34. Quality of Service (QoS) Issues • QoS involves the ability to differentiate between voice and data IP packets, then route them accordingly • The most common problem related to QoS is voice signal degradation • In convergent networks, QoS involves routing IP packets according to information contained in the packet headers

  35. QoS Technologies • One way to prioritize VoIP traffic is to use the Type of Service (ToS) header in IPv4 packets • Another way to prioritize VoIP traffic is to use the Differentiated Services (DiffServ) ToS header, which can distinguish among data types and assign priorities to data streams by marking packets

  36. QoS Technologies (cont'd) • Internet Integrated Services (IntServ) • Enables an application to determine the level of delivery service for its data packets from among several defined choices • Requires each network element to support QoS mechanisms • Requires a means for communicating QoS requirements to each network element on the data stream's path • Requires an end-to-end control message, provided by RSVP

  37. QoS Technologies (cont'd) • Resource Reservation Protocol (RSVP) • RSVP allows an application to request the QoS it needs by sending end-to-end control messages along the data's path • RSVP takes advantage of existing Internet routing protocols and algorithms to carry its messages • RSVP and IntServ operate by reserving capacity in the network, based on the needs of a session, before the session is set up

  38. QoS Technologies (cont'd) • 802.1p • An IEEE signaling standard that prioritizes network traffic at the MAC sublayer of the OSI data link layer by adding priority messages to packet frame headers • 802.1q • An IEEE signaling standard, similar to 802.1p, that was created for implementation in virtual local area networks (VLANs)

  39. Connection QoS: Using Multiple Connections • Connection QoS ensures that the gateway can protect calls from network problems in several ways, including: • Trunk busy-out • Alternative gateway selection • Fallback to the PSTN • The gateway prevents a trunk from servicing a call if: • The IP network fails • The gateway detects an internal problem

  40. Voice Compressionand Decompression • Talk spurts • Voice signal divided into short fragments of20 to 40 bytes • Prevents delay of the voice transmission • Voice compression standards • ITU G-Series protocols • G.711 • G.728 • G.729 • G.729A • G.723.1

  41. Comparing and ContrastingTransmission Media • T1 carrier • A North American high-speed digital carrier • Transmits data at 1.544 Mbps • Time division multiplexing (TDM) device creates 24 channels of 64-Kbps data streams • E1 carrier • A European high-speed digital carrier • Transmits data at 2.048 Mbps • TDM device creates 32 channels of 64-Kbpsdata streams • J1 carrier • Japanese equivalent of T1 carrier

  42. Bandwidth Limitationsfor Voice Traffic • T1 and J1 trunks provide real-time voice traffic for 24 users • An E1 trunk provides real-time voice traffic for 32 users • If a T1 (or J1) and E1 line are connected: • Only about 80 percent of the E1 line would be available • Converting the signaling between the two lines would slow the connection • Modem and fax signaling requirements • All voice and data digital signals enter and exit a network by manipulating the dial tone

  43. VoIP Software and Hardware • VoIP software and hardware allows users to conduct telephone calls between their computers and other VoIP-enabled computers • Line doubling – transmitting data and placing a phone call at the same time using a dial-up connection with IP telephony and the H.323 standard • Advantages of line doubling: • Reduced telephony costs • Off-site workers with access to only one phone line can transmit data and make calls at the same time

  44. VoIP Software and Hardware (cont'd) • Advantages of using VoIP phone technology: • More efficient use of network wiring • Easier relocation and rearrangement of IP-based hard or soft phones • Easier relocation to another building, state or country — anywhere a suitable Internet, intranet or VPN connection is available • Precautions to observe: • Increased traffic on the LAN • Provision of power

  45. Common VoIP Applications • Microsoft NetMeeting – for end point communications on Microsoft Windows systems only • GnomeMeeting – for end point communications on Linux systems • ICUII – for end point communications on various platforms • OpenPhone – a client for Windows that supports end point communications with various clients, including NetMeeting, GnomeMeeting and ICUII

  46. Summary • Discuss the functions of gatekeepers • Discuss the functions of gateways • Define delay, latency, jitter and wander, and identify their impact on real-time communications • Identify the importance of a jitter buffer • Identify the impact of large data frames on real-time communications • Recognize the need for Quality of Service (QoS) for converged networks • Identify QoS technologies for converged networks

  47. Summary (cont'd) • Identify common codecs and their bandwidth requirements in a converged environment • Describe the impact of compressing voice in a network • Compare and contrast the use of T1, E1 and J1 trunks for data and voice • Identify the factors that affect the bandwidth of packetized voice • Identify requirements for transporting modem and fax transmissions through a converged solution

  48. Lesson 3:Network Convergence

  49. Objectives • Identify characteristics of circuit-switched and packet-switched technologies • Identify the differences between the call flow in convergence-based calls and the call flow in circuit-based calls • Identify the types of signaling protocols for converged networks

  50. Characteristics ofConvergent Networks • Integrated Services Digital Network (ISDN) – one of the first attempts to integrate voice and data onto a single network • Three basic voice packet technologies in converged communication networks: • Voice over IP (VoIP) • Voice over Frame Relay (VoFR) • Voice over Asynchronous Transfer Mode (VoATM)

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