Optimizing Integrated Broadband Network Bandwidth Utilization Through Connection Admission ...

245 Pages·2002·3.32 MB·English

by  Steve Oliva

Optimizing
Integrated Broadband Network Bandwidth Utilization
Through Connection Admission Control
Using Weighted Round Robin Queue Server Measurements

by

Stephen A. Oliva
B.S. University of Rhode Island, 1967
M.S. Rutgers University, 1974

Submitted to the Department of Electrical Engineering and Computer
Science and the Faculty of the Graduate School of the University of
Kansas in partial fulfillment of the requirements for the degree of Doctor
of Philosophy.

<Victor S. Frost>_______________________
Chairman
<Joseph R. Evans>______________________
<James D. Church>_____________________
<Swapan Chakrabati>___________________
<David W. Petr>________________________
Committee Members
March 12, 1999______________________
Date dissertation defended
Abstract
This research addresses improvements to network resource utilization through a specific
means of measurement-based control of traffic admission in broadband integrated services
digital networks. A method and system for Connection Admission Control (CAC) in a
communications network, such as an ATM formatted B-ISDN network, is defined, analyzed,
and tested. Using end-to-end virtual path (VP) structures and class-of-service separation,
various network connections, or virtual channels (VC), are administered using a weighted
round robin connection server. Network users aware of this network structure and the means
by which queue lengths are determined may easily calculate a Sustainable Cell Rate (SCR)
for the traffic they wish to introduce into the network path for transmission to a given
destination. The user declared SCR, in addition to other user declared traffic parameters,
determines the queue lengths allocated in the network switches, such that a required level of
Quality of Service (QoS) is maintained. A measurement of certain types of transmitted cells
in a VP, such as idle, unassigned, or low-priority cells, is made at the source of the VP. This
measurement of cells that may be considered to be “empty”, i.e., available for use by high-
priority cells, is used as the basis for a determination of additional allowable connections that
can be admitted to a VP. Relationships and bounds are determined through analysis of the
mean number of “empty” cells per cycle of the connection server and the cell rate bandwidth
that may be allowed to enter a VP that is already “full”, based on the sum of the SCR of its
existing component connections. These relationships are used as the basis of CAC, allowing
connections to be admitted to a “full” virtual path if the cell rate of the requested connection
is less than the allowable cell rate statistically determined from the mean number of “empty”
cell timeslots in the path. Thus, a network VP can support bandwidth greater than the sum of
the SCR of its included connections while maintaining required QoS.
i
Acknowledgements
This dissertation could not have been completed without the support and inspiration of many
people. I would like to acknowledge the contributions of, and thank, the following:
My wife, Marianne, for her encouragement and support of my efforts throughout my
studies and especially through the actual creation of this document. I can never thank her
enough for her patience and understanding on those days during this undertaking where
my approach to life in general was less than optimum.
Dr. Victor Frost, for his guidance, support and encouragement, both as my dissertation
advisor, and as my academic advisor.
My dissertation committee members, Dr. Swapan Chakrabarti, Dr. James Church, Dr.
Joseph Evans, and Dr. David Petr, for their overall encouragement, valuable suggestions,
and careful reading of the document.
Dennis Schnack, for his encouragement and support of my participation in the Sprint
Corporation Advanced Technical Degree Sabbatical Program, as well as Karl Kramer,
Marty Kaplan, and George Fuciu, whose confidence in my abilities and approval of my
participation in the program made this work possible.
Al White, for his steadfast encouragement of my research efforts, and understanding
when things went a little slower than originally anticipated.
Chuck Weber, Steve Drumm, Scott Neal, Antwan Piggott, Ed Wortmann, and other
members of the Sprint Technology Integration and Operations Center team, as well as
Roel Jonkman, of the University of Kansas Information and Telecommunication
Technology Center staff, whose expertise in keeping computer networks working
properly insured the timely and successful completion of simulations described in this
document.
Sprint Corporation, through the Advanced Technical Degree Sabbatical Program, provided
support for this research.
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I dedicate this work to my mother, Elizabeth Oliva, and to the memory of my father, Michael
J. Oliva, to whom I owe everything I have accomplished in life.
Table of Contents

Page
Abstract......................................................................................................................................i
Acknowledgements...................................................................................................................ii
Table of Contents.....................................................................................................................iii
List of Figures..........................................................................................................................vi
List of Tables..........................................................................................................................viii
Chapter 1
Chapter Contents.................................................................................................................1-i
List of Figures.....................................................................................................................1-ii
1. INTRODUCTION..........................................................................................................1-1
1.1 Problem Statement...................................................................................................1-3
1.2 Background..............................................................................................................1-6
1.3 Dissertation Overview...........................................................................................1-49
Chapter 2
Chapter Contents.................................................................................................................2-i
List of Figures.....................................................................................................................2-ii
2. A NEW METHOD FOR DETERMINING AVAILABLE BANDWIDTH..................2-1
2.1 A Model for Determining Available Bandwidth.....................................................2-2
2.2 Choice of Additional Implementation Alternatives...............................................2-11
2.3 Implementing the New Model in a Network.........................................................2-14
2.4 CAC Functions of the Model.................................................................................2-22
2.5 Methodology for Studying WRR Measurement Based CAC................................2-26
iii
2.6 Summary................................................................................................................2-29

Chapter 3
Chapter Contents.................................................................................................................3-i
List of Figures.....................................................................................................................3-ii
3. ANALYSIS OF WRR QUEUE SERVICE MEASUREMENTS...................................3-1
3.1 Summary of the Connection Admission Control (CAC) Scenario..........................3-2
3.2 An Example: Determination of SCR using Equivalent Capacity............................3-4
3.3 Determination of Mean Empty Timeslots per WRR Cycle.....................................3-6
3.4 Determination of Available Capacity in a “Full” Virtual Path..............................3-11
3.5 Admission of “Additional” Traffic........................................................................3-43
3.6 Considerations in Admitting “Additional” Traffic................................................3-54
3.7 Summary................................................................................................................3-56
Chapter 4
Chapter Contents.................................................................................................................4-i
List of Figures.....................................................................................................................4-ii
List of Tables.....................................................................................................................4-iii
4. EVALUATION AND DISCUSSION OF RESULTS....................................................4-1
4.1 Evaluation: Traffic and Path Model Simulation......................................................4-1
4.2 Discussion of Results.............................................................................................4-22
4.3 Summary................................................................................................................4-23

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Chapter 5
Chapter Contents.................................................................................................................5-i
List of Figures.....................................................................................................................5-ii
5. CONCLUSIONS AND FUTURE DIRECTIONS.........................................................5-1
5.1 Conclusions..............................................................................................................5-1
5.2 Future Directions...................................................................................................5-11

References.............................................................................................................................R-1
Appendix A...........................................................................................................................A-1
Appendix B...........................................................................................................................B-1
Appendix C...........................................................................................................................C-1
Appendix D...........................................................................................................................D-1
Appendix E.............................................................................................................................E-1
v
List of Figures

Figure 1-1: Classification of CAC Schemes.................................................................1-16
Figure 1-2: Network Model, No Core Switches............................................................1-43
Figure 1-3: Network Model, Using Core Switches.......................................................1-43
Figure 1-4: Step By Step CAC......................................................................................1-45
Figure 1-5: Parameter Database and Control System CAC..........................................1-45
Figure 1-6: End-to-End Path Based...............................................................................1-46
Figure 2-1: Basic WRR Path Queuing Model................................................................2-4
Figure 2-2: WRR Scheduling of Three Traffic Streams (Example)................................2-7
Figure 2-3: Rigid Cycle Scheduling with Idle Cell in Empty Slot (Example)................2-7
Figure 2-4: WRR Scheduling with Empty Slot (Example).............................................2-8
Figure 2-5: WWR Schedule with Added Traffic Stream (Example)..............................2-8
Figure 2-6: WRR Schedule with Queue Skipped (Example A)......................................2-9
Figure 2-7: WRR Schedule with Queue Skipped (Example B)....................................2-10
Figure 2-8: Source Switch Functionality.......................................................................2-18
Figure 2-9: Destination Switch Functionality...............................................................2-21
Figure 2-10: Virtual Path with N Virtual Channels to Given Destination....................2-23
Figure 2-11: Network Model for Analysis and Evaluation Summary..........................2-28
Figure 3-1:WRR Path Queuing Model for CBR/VBR Traffic........................................3-3
Figure 3-2: Normal Approximation to a Binomial Distribution, N=10, p=.5...............3-27
Figure 3-3: Worst Case Maximum Burst Relationships for Policed Traffic.................3-37
Figure 3-4: Worst Case Scenario for M Queues of GCRA Policed Traffic..................3-38
Figure 3-5: Added Connection Cell Rate, Single Empty Timeslot Method..................3-41
Figure 3-6: Added Connection Cell Rate, Multiple Empty Timeslot Method..............3-41
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Figure 3-7: Typical Correlation Coefficients of Samples of X......................................3-49
Figure 3-8: Estimated Correlation Coefficients of X.....................................................3-49
Figure 4-1: Empty Timeslots per Cycle, Short Burst Traffic Stream Scenario...............4-8
Figure 4-2: Empty Timeslots per Cycle, Long Burst Traffic Stream Scenario...............4-9
Figure 4-3: Typical Estimated Allowable Mean Over 10,000 WRR Cycles................4-16
Figure 4-4: Allowable Mean from 10 Queue Scenario.................................................4-17
Figure 4-5: Allowable Mean from 20 Queue Scenario.................................................4-18
Figure 4-6: Typical “Added” Queue Simulation Results..............................................4-21
Figure 5-1. CAC Algorithm............................................................................................5-9

vii
List of Tables

Table 1-1: ATM Source Category Attributes..............................................................................1-12
Table 4-1. Mean Empty Timeslots per Cycle, Scheduled and Skipped Queue Models...............4-10
Table 4-2. Typical Mean, Variance and Minimum Estimated Variance of Sample Means.........4-13

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Chapter 1

Introduction