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CSE 588 - Spring 2002 - Transcription
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QOS
Parameters:
1.
Fixed/Variable
rate
2.
Tolerant of delay
or loss
3.
Delay Adaptive or
Rate Adaptive
Rate Adaptive: Change compression rate to fill available
bandwidth
Delay Adaptive: If falling behind, slow down tranmission
rate
4.
Multicast
Aggregate Reservations
5.
Closed or Open
Loop
Applications having
Quality of Service requirements
1.
Surgery (Closed
Loop, Not Adaptive, Fixed Rate)
2.
Remote Aircraft
Control (Tolerant of loss)
3. Air
Traffic
Control
4.
Stock Quotes
(Semi Tolerant, Non Adaptive, Fixed Rate, Can have
Reservations)
5.
Internet
Telephony (Semi Tolerant of Loss, Delay Adaptive but has limits of
absolute
delay)
6.
Video Games (Like
Telephony or Surgery)
7.
Video
Conferencing (like Telephony)
8. Web
Surfing
(Tolerant of Loss, Rate Adaptive)
9.
Broadcast
(Tolerant of Delay)
What
would be the
Application which would possibly cause development or investment in
this?
Possibilities
are:
Video
Conferencing
Broadcast
Video
Games
RSVP
Paper:
Any
new architecture
can be divided into 5 components:
1.
Flow
Spec:
Flow
can be
Fixed Rate or Variable Rate. Issues are: If it is Variable Rate, how do
we
control the rate? One proposal is the Leaky Bucket method. We assume an
average
rate of flow r and an overflow buffer of size b. We could try the
Statistical
Rate method: We say that there is a probablity p that the combination of
r and b
are above a certain threshold. This method, however, has problems in
Policing
and Pricing.
2.
Admission
Control
Approaches:
a)
Overprovisioning
+ Pricing: Pure Overprovisioning does not work because of
TCP, since TCP is
guaranteed to congest any network.
b)
Strict
Guarantees: This has scalability issues. Max guarantee
offerred is
limited by the point in the network with the lowest BW, whether or
not
that is used in all traffic flows.
c) Weak Guarantees: Users can have
higher priorities
for certain traffic.
d) Measurement Based
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University of Washington
Box 352350
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