The Application Layer Chapter 7 7.4 - 7.5. Computer Networks, Fifth Edition by Andrew Tanenbaum and...
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Transcript of The Application Layer Chapter 7 7.4 - 7.5. Computer Networks, Fifth Edition by Andrew Tanenbaum and...
![Page 1: The Application Layer Chapter 7 7.4 - 7.5. Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall,](https://reader033.fdocuments.net/reader033/viewer/2022061616/56649eec5503460f94bfdefb/html5/thumbnails/1.jpg)
The Application Layer
Chapter 7
7.4 - 7.5
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Streaming Audio and Video
• Digital audio• Digital video• Streaming stored media• Streaming live media• Real-time conferencing
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Digital Audio (1)
(a) A sine wave. (b) Sampling the sine wave. (c) Quantizing the samples to 4 bits.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Digital Audio (2)
(a) The threshold of audibility as a function of frequency. (b) The masking effect.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Digital Video (1)
Steps in JPEG lossy sequential encoding.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Digital Video (2)
(a) RGB input data. (b) After block preparation.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Digital Video (3)
(a) One block of the Y matrix. (b) The DCT coefficients.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Digital Video (4)
Computation of the quantized DCT coefficients.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Digital Video (5)
The order in which the quantized values are transmitted.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Digital Video (6)
MPEG output consists of three kinds of frames:a) I- (Intracoded) :
Self-contained compressed still pictures.b) P- (Predictive) : Block-by-block difference
with previous frames.c) B- (Bidirectional) : block-by-block differences
between previous and future frames.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Digital Video (7)
Three consecutive frames
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Streaming Stored Media (1)
Playing media over the Web via simple downloads.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Streaming Stored Media (2)
Streaming media using the Web and a media server.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Streaming Stored Media (3)
Major tasks of the media player:
1. Manage the user interface.2. Handle transmission errors.3. Decompress the content.4. Eliminate jitter.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Streaming Stored Media (4)
Using a parity packet to repair loss.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Streaming Stored Media (5)
When packets carry alternate samples, the loss of a packet reduces the temporal resolution
rather than creating a gap in time.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Streaming Stored Media (6)
The media player buffers input from the media server and plays
from the buffer rather than directly from the network.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Streaming Stored Media (7)
RTSP commands from the player to the server.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Streaming Live Media (1)
Multicast streaming media with a parity packet.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Streaming Live Media (2)
A student radio station.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Real-Time Conferencing (1)
The H.323 architectural model for Internet telephony.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Real-Time Conferencing (2)
The H.323 protocol stack.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Real-Time Conferencing (3)
Logical channels between the caller and callee during a call.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Real-Time Conferencing (4)
SIP methods.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Real-Time Conferencing (5)
Use of a proxy server and redirection with SIP.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Real-Time Conferencing (6)
Comparison of H.323 and SIP.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Content Delivery
• Content and internet traffic• Server farms and web proxies• Content delivery networks• Peer-to-peer networks
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Content and Internet Traffic
Zipf distribution (a) On a linear scale. (b) On a log-log scale.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Server Farms and Web Proxies (1)
A server farm.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Server Farms and Web Proxies (2)
A proxy cache between Web browsers and Web servers.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Content Delivery Networks (1)
CDN distribution tree.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Content Delivery Networks (2)
Directing clients to nearby CDN nodes using DNS.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Content Delivery Networks (3)
(a) Original Web page. (b) Same page after linking to the CDN
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Peer-to-Peer Networks (1)
Problems to be solved with BitTorrent sharing
1. How does a peer find other peers2. How is content replicated by peers to
provide high-speed downloads3. How do peers encourage each other to
upload content to others
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Peer-to-Peer Networks (2)
BitTorrent.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
Peer-to-Peer Networks (3)
(a) A set of 32 node identifiers arranged in a circle. The shaded ones correspond to actual machines. The arcs show the
fingers from nodes 1, 4 and 12. The labels on the arcs are the table indices. (b) Examples of the finger tables.
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Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011
End
Chapter 7