Transport Protocols

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Transport Protocols
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TCP Header Format
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Credit Allocation
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Flow Control Perspectives
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Window Scale
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Exponential Smoothing Coefficients
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Exponential Averaging
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Exponential Averaging
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TCP Segment Pacing
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TCP Segment Pacing
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Bottlenecks
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Jacobsons RTO AlgorithmTahoe
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Slow Start and Congestion Avoidance
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Slow Start
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Fast Retransmit
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Fast Recovery
TCP Reno Karn/Partridge, set Timeout to double
each time a retransmit occurs
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TCP/IP over AAL5
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Buffer Layout for Selective Drop
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Comparison
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RED
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Fairness
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Tradeoffs
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MINTH
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Queue Size
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Fairness
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Fairness
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Minth and MAXP
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MAXP
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MAXp
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Power
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(No Transcript)
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Real Time Packet Transmission
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Real Time

• Hard Real Time Difficult to implement, packets
  must arrive or there will be failure
• Soft Real Time Application can tolerate the
  loss of some packets
• RTP is suited for Soft Real Time

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Application Level Framing

• Reliability guaranteed by application
• Instead of retransmitting, the receiver may ask
  the source to send at a lower quality
• The sender may be able to recompute the data
  instead of buffering it.
• The sender may fix the problem and send different
  data on error.
• Data is broken into Application Data Units which
  either arrive in tact or are all deleted

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RTP Fundamentals

• Provides multicast capability
• Each packet includes a timestamp
• Two RTP relays
• Translators Convert to lower quality video
• Mixers receives two or more streams and mixes
  the result (audio)

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RTP Control Protocol

• Report quality of service for the multicast tree.
• Report excessive jitter or other information to
  diagnose faults

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RTP Protocol
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Problems

• 5) Calculate SRTT, given an initial small SRTT
  value, it can take a long time to converge on the
  correct value

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10.6 Silly Window Syndrome

• Initial credit of 1000
• Sender uses up with 5 200 byte segments
• Sender now thinks the window is of length 0
• Receiver is at a push point and pops 50 bytes to
  upper layer and acks with a 50 byte credit
• After this Ack, the sender has only 50 bytes to
  send, so this becomes a segment
• When receiver gets the 50 bytes, it returns a
  credit of 50 and the sender then sends only 50 .

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10.11

• Slow start with long delay like we did in class

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10.14

• What buffer is required to deal with jitter
• 30 frames per second at 1024x1024x3bytes3Mbytes/f
  rame
• Jitter of 2 seconds, what is buffer required?