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Diffusion Mechanisms for Active Queue Management

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Random Early Detection (RED) Random packet drops in queue. ... Diffusion Early Marking decides whether to mark a packet or not as: Where: M=2, b1=2/3, b2=1/3 ... – PowerPoint PPT presentation

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Title: Diffusion Mechanisms for Active Queue Management


1
Diffusion Mechanisms for Active Queue Management
Rafael Nunez nunez_at_ece.udel.edu
Gonzalo Arce arce_at_ece.udel.edu
  • Department of Electrical and Computer Engineering
  • University of Delaware
  • May 19th / 2004

2
Diffusion Mechanisms for Active Queue Management
  • Introduction
  • Diffusion Early Marking
  • Performance
  • Conclusions and Future Work

3
The Internet Today
4
Congestion
  • Desirable control distributed, simple, stable
    and fair.

5
Problems with Tail Dropping
  • Penalizes bursty traffic
  • Discriminates against large propagation delay
    connections.
  • Global synchronization.

6
Active Queue Management (AQM)
  • Random Early Detection (Floyd and Jacobson, 1993)
  • Router becomes active in congestion control.
  • RED has been deployed in some Cisco routers.

7
Random Early Detection (RED)
  • Random packet drops in queue.
  • Drop probability based on average queue
  • Four parameters
  • qmin
  • qmax
  • Pmax
  • wq
  • (overparameterized)

8
Queue Behavior in RED
9
Queue Behavior in RED (2)
  • 20 new flows every 20 seconds
  • Wq 0.01
  • Wq 0.001

10
Other AQMs Schemes
  • Adaptive RED, REM, GREEN, BLUE,
  • Problems
  • Over-parameterization
  • Not easy to implement in routers
  • Not much better performance than drop tail

11
Diffusion Mechanisms for Active Queue Management
  • Introduction
  • Diffusion Early Marking
  • Performance
  • Conclusions and Future Work

v
12
Diffusion Mechanisms for AQM
  • Instantaneous queue size.
  • Better packet marking strategy.
  • Simplified parameters.

13
Probability of Marking a Packet
  • Gentle RED function closely follows

(A)
14
Evolution of the Congestion Window
  • TCP in steady state

(B)
15
Traffic in the Network
  • Congestion Window Packets In The Pipe Packets
    In The Queue
  • Or

(C)
  • From (A), (B), (C), and knowing that

where
16
Probability Function
17
Error Diffusion
  • Packet marking is analogous to halftoning
  • Convert a continuous gray-scale image into black
    or white dots
  • Packet marking reduces to quantization
  • Error diffusion The error between input
    (continuous) and output (discrete) is
    incorporated in subsequent outputs.

18
Diffusion Mechanism
19
Diffusion Mechanism
20
Diffusion Mechanism
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Diffusion Mechanism
22
Diffusion Mechanism
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Diffusion Mechanism
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Diffusion Mechanism
25
Diffusion Mechanism
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Diffusion Mechanism
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Diffusion Mechanism
28
Diffusion Mechanism
29
Diffusion Mechanism
30
Algorithm Summary
  • Diffusion Early Marking decides whether to mark a
    packet or not as

Where
Remember
M2, b12/3, b21/3
31
Diffusion Mechanisms for Active Queue Management
  • Introduction
  • Diffusion Early Marking
  • Performance
  • Conclusions and Future Work

v
v
32
Dropping Packets
33
Window Size
2 Flows
10 Flows
34
Stability of the Queue
  • 100 long lived connections (TCP/Reno, FTP)
  • Desired queue size 30 packets

35
Changing the number of flows
  • 20 new flows every 20 seconds

36
Diffusion Mechanisms for Active Queue Management
  • Introduction
  • Diffusion Early Marking
  • Performance
  • Conclusions and Future Work

v
v
v
37
Conclusions and Future Work
  • Queue length stabilized and controlled without
    adjusting parameters.
  • Diffusion mechanism improves the behavior of the
    proposed AQM scheme.
  • Future Work
  • Estimation of parameters
  • Analyze more traffic scenarios
  • Compare with other AQMs
  • Use diffusion mechanism in other AQMs

38
Diffusion Mechanisms for Active Queue Management
  • Introduction
  • Diffusion Early Marking
  • Parameter Estimation
  • Conclusions and Future Work

v
v
v
v
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