A Guide to Designing and Implementing Local and Wide Area Networks_ 2e

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A Guide to Designing and Implementing Local and Wide Area Networks_ 2e Powered By Docstoc
					Chapter 10
   Explain analog and digital video technologies
   Describe audio file technologies
   Explain audio and video sampling
   Describe Voice over IP
   Assess bandwidth and throughput on a
   Explain how multimedia transmissions work
   Design LANs and WANs for multimedia
   Discuss multimedia issues of the future
   Roots in analog TV
   Analog and digital video technologies
   Main video technologies used on computers
       Audio Video Interleave (AVI)
       Moving Pictures Expert Group (MPEG)
       Fractal image
       Apple Quicktime
       Adobe Flash
   Primarily associated with television
   Television broadcast standards
       National Television Standards Committee (NTSC)
         525 vertical scan lines; 30 frames per second
       Phase alternation line (PAL)
         625 vertical scan lines; 25 frames per second
       System Electronique Couleur Avec Memoire
   Commonplace on the Internet
   Increased distances
   Sharper images
   Network video transmissions involve several
    technologies; digital television uses one
   AVI
       Interleaves video and audio data to be reproduced as
        short clips
   MPEG
       Standard set by the MPEG within the ISO
   Fractal image compression
       Uses properties of fractals, duplicated images, and
        mapping to compress frames
   Lossy compression
   Predicted encoding
   Bidirectional interpolation
   Official Homepage -
   Store on server for clients to download as a file
    and play using MPEG player software
   Streaming the file over a network link
   Algebraic-Code-Excited Linear Prediction
   Audio Code Number 3 (AC-3), which is Dolby
    digital surround sound
   Adaptive Differential Pulse Code Modulation
   Audio Interchange File Format (AIFF)

   Global System for Mobil Communication
   Interchange File Format (IFF)
   Musical Instrument Digital Interface (MIDI)
   MPEG-1 Audio
   MPEG-2 Audio
   MPEG-4 Audio
   MPEG-7 Audio

   Open Document Architecture Audio Content
    Architecture (ODA ACA)
   Pulse code modulation (PCM)
   Sub-band adaptive differential pulse code
    modulation (SB-ADPCM)
   Waveform audio file format (WAV)
       Used in media player
   MPEG
       Used in many diverse kinds of applications
   WAV (particularly PCM U-law)
       Used to play music over the Internet
   Samples of an analog signal taken at specific
    intervals construct a digital signal
   Type of sampling technique influences the
    quality of the signal
   Internet radio and downloading music files
   Audio and video conferencing
   Online courses and seminars
   E-mail attachments
   Local and national news broadcasts
   Telephone messaging services
   Seminars
   Movies
   Live out-of-classroom help from teachers
   Interviews
   Physician training about pharmaceutical
   Integration of telephone, TV, computer, and
   Wireless, handheld audio/video devices for
    visitors to a new city
   Provides telephony communications over an IP
   Used by some companies as an alternative to
    PBXs, PAXs, and PABXs
   Telephone device
       Converts voice sounds into binary, then into IP
   Call processor or call server
       Sets up and terminates calls
       Manages a calling session
       Translates telephone numbers or IDs into IP
   Specialized gateway
       Converts IP packetized voice data into a signal that
        can be transmitted over a PSTN
   ITU H.323
   Session Initiation Protocol (SIP)
   Media Gateway Control Protocol (MGCP)/
   Outlines several types of devices for voice
   Used with several accompanying standards for
    compression/decompression (codec) and voice
    communications handling
   Signaling protocol created by IETF
   Used to start or stop a VoIP communications
   Uses commands modeled after HTTP
   Uses URLs for addressing
   Advantages
       Can be used over the Internet or on an IP LAN,
        MAN, or WAN
       Can be used with H.323 systems
   Designed to handle translation of an audio
    signal to a VoIP network
   Relatively low overhead; uses UDP for audio
    communications over an IP network
   Compatible with networks that use SIP
   Bandwidth
       Transmission capacity of a communications medium
       Typically measured in bits per second (data) or hertz
        (some data, voice, and video)
       Determined by maximum minus minimum
        transmission capacity
   Throughput
       Amount of traffic passing through given point on
        network at given time
   Download time in seconds = file size in bytes *
    10 /connection speed in bps
   File compression and file format compatibility
   Synchronization
   Latency
   Jitter
   File compression
       Reduces size of a normal file by using techniques to
        remove redundant information or blank areas in
        file’s structure
   Ensures all constituent pieces are assembled
    and played in the right order
   Most reliable with adequate bandwidth
   Time it takes for networked information to
    travel from transmitting device to receiving
   Influenced by:
     Transmission delay
     Propagation delay
     Processing delay
     Store-and-forward or switching delay
   Presence of variable latency on a network
   Causes evident reproduction errors
       Clicks or pops in audio playback
       Jerky or delayed response in video
   Typically occur between two devices (sender
    and receiver) with a LAN, WAN, or both in
   Different methods
       Using network resources (eg, routers)
       Creating transmissions that generate relatively more
        network traffic
   Unicast
   Broadcast
   Multicast
Description                 Limitations
One copy of each frame      Difficult to scale up
or packet is sent to each   multimedia applications
destination point           for increased numbers of
                            If many users, traffic
                            volume is high and
                            requires high bandwidth
Description                Limitations
One copy of each frame     If not filtered by
or packet is sent to all   internetworking devices,
points on a network,       multimedia broadcast
regardless of whether or   traffic can produce even
not a node has requested   more load on a network
it                         than unicasts, because it
                           potentially goes to more
Description                Limitations
Server divides users who   More difficult to develop
request certain            applications to use
applications into groups   multicasting, but the
Each data stream of        payoff in improved
frames or packets is a     network control and
one-time transmission      traffic patterns is well
that goes to multiple      worth the effort
   Same application under different transmission
   Role of Internet Group Management Protocol
   Additional Protocols to Accommodate
     Distance Vector Multicast Routing Protocol
     Multicast Open Shortest Path First Protocol (MOSPF)
     Protocol Independent Multicast (PIM)
   Works with RIP to determine:
       Which workstations are subscribed to multimedia
       Fewest hops to a particular router on a network
       Route to take to reach a particular router
   Works like OSPF in finding the shortest path
    from source to destination for multicast
   Compatible with networks that use OSPF or
    RIP as their main routing protocol
   Real-Time Protocol (RTP)
       Multicast protocol developed for real-time
        multimedia applications
   Real-Time Transport Control Protocol (RTCP)
       Works with RPT to provide specific controls over
        multicast transmissions
       Provides management information
   Resources Reservation Protocol (RSVP)
       Used on TCP/IP-based networks
       Enables an application to reserve computer and
        network resources it needs (bandwidth, buffers,
        maximum burst, classes of service)
       Dynamically allocates resources as demands increase
        or decrease
       Also know as the Resource Reservation Setup
   Redesigning legacy networks for multimedia
   Deploying high-speed Ethernet on multimedia-
    based LANs
   Designing WANs that carry multimedia
    applications with ease
   Add switches and routers
   Match WAN to speed and application
    requirements of the connected LANs
   Schedule WAN usage around application use
   Deploy multiple video servers at different sites
    throughout the LAN/WAN
   Snapshot routing
   IPX/SPX spoofing
   Bandwidth on demand
   Network-based computer instruction
   Video conferencing
   Streaming applications
   Analog and digital video technologies
   Audio file technologies
   Audio and video sampling
   Integrating voice, video, and data on a network
   Voice over IP (VoIP)
   How to assess bandwidth and throughput on a

   Packet and frame transmission techniques for
    integrated multimedia applications
   How to design LANs and WANs to handle
    multimedia traffic
   Issues that will affect how multimedia is
    transported in the future

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