CSE 588 - Spring 2002 - Transcription

University of Washington Department of Computer Science & Engineering

CSE Home

Week 9 - Quality of Service (1st half of class)

Real time networking

Needed in

surgery

        military
        remote aircraft
        air traffic control
        stock quotes
        broadcast
        online gaming
        audio/video conference
        web surfing

Fixed or Variable rate?

Tolerant of delay or loss of data?

Adaptive

Rate Adaptive

Change compression to fill available bandwith.

Delay Adaptive

If your falling behind then slow down the playback

Which of the applications will drive the industry?
games - consumer demand
audio/video conferencing - corporate demand

stock quotes

Four main peices to QoS model
    Flowspec
    Admission Control
    Reservation Protocol
    Scheduling

Flowspec
Fixed Rate

Variable Rate

Do we have control of the rate?

Leaky bucket

send at an average rate

buffer overflow

Need rate aware compression (MPEG)
Statistical rate could be used also

    Application can't predict demand
    Can't have a real time guarentee without policing
    Pricing model
         Is it manipulative, dynamic

Pricing model seems realistic and worthwhile

Admission Control - Does someone get in?

Pricing may help determine this

Connection limits

1. Over provision - always make sure you have enough resources

2. Strict provision - only guaruntee service if you know you can fulfill the request

3. Weak provision - guaruntee service if you think it will be OK

4. Measurement based - in between strict and weak

    Which should we use?
        Over provision can't work by itself.
        Strict provision isn't scalable.
        Weak provision isn't reliable.

    Over provision with a pricing model looks promising.

Will require priorities.

Department of Computer Science & Engineering
University of Washington
Box 352350
Seattle, WA 98195-2350
(206) 543-1695 voice, (206) 543-2969 FAX
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