Chapter 28. Network Management Chapter 29. Multimedia

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Chapter 28.Network ManagementChapter
29.Multimedia
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Network Management System and SNMP Concepts
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Internet Audio/Video

• Streaming stored audio/video refers to on-demand
  requests for compressed audio/video files
• Streaming live audio/video refers to the
  broadcasting of radio and TV programs through the
  Internet
• Interactive audio/video refers to the use of the
  Internet for interactive audio/video applications

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Digitizing Audio and Video

• Digitizing audio
• Voice 64 Kbps 8,000 samples x 8 bits
• Music 44,100 samples x 16 bits -gt
• 705.6 Kbps for mono, 1,411 Mbps for
  stereo
• Digitizing video
• 25 frames/second, 1024 x 768 pixels, 24
  bits/pixel
• 2 x 25 x 1024 x 768 x 24 944 Mbps
• Compression is needed to send video (audio) over
  the Internet
• Audio Compression
• Predictive encoding GSM(13Kbps), G.729(8Kbps),
• G.723.3(6.4 or
  5.3 Kbps)
• Perceptual encoding MP3 (MPEG audio layer 3)
• Video Compression
• Image compression JPEG
• Video compression MPEG

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Streaming Stored AV (1)

• First approach Using a Web server

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Streaming Stored AV (2)

• Second approach Using a Web server with metafile

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Streaming Stored AV (3)

• Third approach Using a media server

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Streaming Stored AV (4)

• Fourth approach Using a media server and RTSP

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Real-time Interactive AV

• Time relationship

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Real-time Interactive AV

• Jitter is introduced in real-time data by the
  delay between packets

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Timestamp

• To prevent jitter, we can timestamp the packets
  and separate the arrival time from the playback
  time

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Playback Buffer

• A playback buffer is required for real-time
  traffic

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Characteristics of Real-time AV Communication

• A sequence number on each packet is required for
  real-time traffic
• Real-time traffic needs the support of
  multicasting
• Translation means changing the encoding of a
  payload to a lower quality to match the bandwidth
  of the receiving network
• Mixing means combining several streams of traffic
  into one stream.
• Support from transport layer protocol
• TCP, with all its sophistication, is not suitable
  for interactive multimedia traffic because we
  cannot allow retransmission of packets.
• UDP is more suitable than TCP for interactive
  traffic. However, we need the services of RTP,
  another transport layer protocol, to make up for
  the deficiencies of UDP

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Real-time Transport Protocol (RTP)

• RTP is designed to handle real-time traffic on
  the Internet
• RTP uses a temporary even-numbered UDP port

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Real-time Transport Control Protocol (RTCP)

• RTCP is designed to control the flow and quality
  of data and allow the recipient to send feedback
  to the source or sources
• RTCP uses an odd-numbered UDP port number that
  follows the port number selected for RTP

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Voice over IP

• Session Initiation Protocol (SIP) by IETF and
  H.323 by ITU-T
• SIP

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SIP Simple Session
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Tracking the Callee
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H.323 Architecture and Protocols
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H.323 Example