Table Of ContentProgress in Communication Networks
Volume 1
Series Editor: Harmen R. van As
Admela J ukan
QoS-based Wavelength Routing
in Multi-Service WDM Networks
Springer-Verlag Wien GmbH
Admela Jukan
Institute ofCommunication Networks, Vienna University ofTechnology,
Vienna, Austria
This work is subject to copyright.
All rights are reserved, whether the whole or part ofthe material is concemed,
specifically those of translation, reprinting, re-use of illustrations, broadcasting,
reproduction by photocopying machines or similar means, and storage
in data banks.
Product Liability: The publisher can give no guarantee for all the information contained
in this book. This does also refer to information about drug dosage and application thereof.
In every individual case the respective user must check its accuracy by consulting
other pharmaceuticalliterature. The use ofregistered names, trademarks, etc.
in this publication does not imply, even in the absence of a specific statement,
that such names are exempt from the relevant protective laws and regulations
and therefore free for general use.
© 2001 Springer-Verlag Wien
Softcover reprint of the hardcover 1s t edition 2001
Typesetting: Camera-ready by author
Printed on acid-free and chlorine-free bleached paper
SPIN: 10798728
With 101 Figures
CIP-data applied for
ISBN 978-3-7091-7268-1 ISBN 978-3-7091-6247-7 (eBook)
DOI 10.1007/978-3-7091-6247-7
PREFACE
The need to establish wavelength-routed connections in a service-differentiated fash
ion is becoming increasingly important due to a variety of candidate client networks
(e.g. IP, SDH/SONET, ATM) and the requirements for Quality-of-Service (QoS) de
livery within transport layers. Up until now, the criteria for optical network design
and operation have usually been considered independently of the higher-layer client
signals (users), i.e. without taking into account particular requirements or constraints
originating from the users' differentiation. Wavelength routing for multi-service net
works with performance guarantees, however, will have to do with much more than
finding a path and allocating wavelengths. The optimisation of wavelength-routed
paths will have to take into account a number of user requirements and network con
straints, while keeping the resource utilisation and blocking probability as low as pos
sible. In a networking scenario where a multi-service operation in WDM networks is
assumed, while dealing with heterogeneous architectures (e.g. technology-driven, as
transparent, or regenerative), efficient algorithms and protocols for QoS-differentiated
and dynamic allocation of physical resources will playa key role.
This work examines the development of multi-criteria wavelength routing for WDM
networks where a set of performances is guaranteed to each client network, taking
into account network properties and physical constraints. A wide range of unique so
lutions are proposed, ranging from those that intrinsically differ in the way of dealing
with quality attributes, and are primarily concerned with user's satisfaction at quality
and restorability, to distributed-like solutions, concerned with fast, scalable, and accu
rate maintenance of the link state information. Yet, common to all solutions proposed
here is a generic approach to service-differentiated connection accommodation, where
for the network state representation, the supplementary network graphs are defined
and referred to as service-specific wavelength-resource graphs. These graphs are used
for the appropriate allocation of wavelengths on concatenated physical resources
which build a wavelength route, along which the necessary transmission quality is
achieved and the required management and surveillance functions are provided.
By considering twofold wavelength routing metrics, i.e. QoS metrics (service re
quirements) and resource metrics (quality constraints), the above generic approach
can yield the solution to the QoS-routing problem, i.e. provision of service-specific
guarantees under quality constraints, a feature that is still missing from the existing
architectures. To facilitate understanding of a fundamentally new paradigm in trans
port layer networking -a wavelength service -a fair amount of this work is also dedi
cated to the basic subjects related to wavelength routing, such as analytical modelling
of blocking, network architecture, and benefits of wavelength shifting. Finally, an
extensive numerical analysis of dynamically re-configurable multi-service WDM
networks is presented for regular network operation as well as for optical network
service restoration. The numerical results confirm applicability and alleged properties
of the proposed solutions and give clear directions for further study and research.
ACKNOWLEDGEMENTS
My sincere appreciation and thanks to my advisor, Prof. Harmen R. van As, who no
bly accepted and encouraged my individuality and gave me a great support in all my
professional pursuits. Prof. van As taught me to work with perseverance, enthusiasm
and fashion, and, most of all, with a genuinely human attitude.
I am very grateful to my co-adviser Prof. Maurice Gagnaire from Ecole Nationale
Superieure des Telecommunications in Paris as well, for his commitment and sup
port in the end phase of my thesis work.
In finalising this book, a serious administrative, editorial and printing work has been
done, for which I especially and v.v. much want to thank Johanna Pfeifer.
In times of the biggest hecticness, Zuzana Kovacovsky, the best secretary in the
world and a great fellow, helped ohne wenn und aher with all possible matters.
Thanks for everything.
I dedicate this book to my parents: most profoundly, I thank my mother for loving me
ingeniously and enriching my spirits with poetry, and I thank my father, who has
never stopped asking "What's next?".
CONTENTS
1 Introduction ..................................................................................... 1
1.1 This thesis ....................................................................................................... 4
1.2 Overview ........................................................................................................ 4
2 A QoS-based optical networking. ................................................... 6
2.1 From quality attributes to QoS in optical networks ................................... 6
2.2 Wavelength-routed network architecture ................................................. 11
2.2.1 Applications and waveband hierarchies ................................................. 17
2.3 A QoS-selective architecture. ...................................................................... 24
2.4 Basic management and control issues ....................................................... 29
2.4.1 QoS management for wavelength-routed networks ................................ 33
2.5 Restoration in wavelength-routed networks ............................................. 34
2.5.1 A simple taxonomy for service restoration ............................................. 36
2.5.2 Optical network service restoration ........................................................ 43
3 Service-differentiated connection set-up ..................................... 47
3.1 Wavelength-routed services: a debate ....................................................... 47
3.2 Client layer perspectives ............................................................................. 50
3.3 The basic model for connection management ........................................... 56
3.4 Connection and resource management architecture ................................ 59
3.4.1 Parameter translation between optical and non-optical layers ................ 60
3.4.1.1 Transmission quality ........................................................................ 60
3.4.1.2 Restorability .................................................................................... 61
3.4.1.3 Manageability .................................................................................. 61
3.4.1.4 Security ............................................................................................ 62
3.5 Two methods for connection set-up ........................................................... 62
3.5.1 The basic flows for the service-specific connection set-up .................... 66
VIII
3.5.2 A functional model for service-specific restoration ................................ 69
4 The methods based on graph transformation ............................. 72
4.1 Two methods for QoS-routing revisited .................................................... 72
4.2 Abstraction of the network state representation ...................................... 75
4.2.1 A few basic notations for graphs ............................................................ 75
4.2.2 Graph transformation .............................................................................. 79
4.2.3 Weight labelling ..................................................................................... 87
4.2.3.1 Network element allocation ............................................................. 88
4.2.3.2 Network element connection ........................................................... 90
4.2.4 Operations with multi-dimensional metrics ............................................ 92
4.2.5 Solving routing problems with single (mixed) metric ............................ 97
4.2.6 Solving routing problems with multiple metrics (QoS-routing) ............. 99
4.2.7 Multi-constraint routing problem revisited ........................................... 101
5 Algorithms for QoS-based wavelength routing ........................ 104
5.1 Wavelength routing update ...................................................................... 104
5.2 Benefits of wavelength shifting ................................................................. 110
5.2.1 Mathematical modelling ....................................................................... 112
5.2.2 Influence of load correlation ................................................................. 117
5.2.3 Sparse and limited-range wavelength shifting ...................................... 120
5.3 Algorithms for service-specific wavelength routing ............................... 122
5.3.1 The methods with service-specific wavelength grouping ..................... 123
5.3.1.1 Least quality wavelength allocation .............................................. 126
5.3.1.2 Minimisation of resource utilisation .............................................. 130
5.3.1.3 Alternate routing for overloaded multi-wavelength resources ...... 136
5.3.2 The algorithms based on graph transformation .................................... 137
5.3.2.1 General algorithm with graph transformation ............................... 139
5.3.2.2 Least quality wavelength routing with graph transformation ........ 142
5.3.2.3 Service-specific minimisation of wavelength shifting ................... 143
IX
5.3.2.4 Service-specific signal regeneration .............................................. 144
5.3.3 Separation of service attributes and routing function ........................... 146
5.3.4 A distributed QoS-routing method ....................................................... 147
5.4 Methods for service-specific restoration .................................................. 150
5.4.1.1 Dynamic path restoration (DPR) ................................................... 153
5.4.1.2 Dynamic link restoration (DLR) .................................................... 155
5.4.1.3 Static path restoration (SPR) ......................................................... 155
5.4.1.4 Static link restoration (SLR) .......................................................... 156
5.4.1.5 Shared wavelength path restoration (SWPR) ................................ 157
5.4.1.6 Shared wavelength link restoration (SWLR) ................................. 157
5.4.1.7 A comparison between different restoration methods ................... 158
5.4.1.8 Link-disjoint path algorithm .......................................................... 160
5.4.1.9 Node-disjoint path algorithm ......................................................... 162
6 Performance study and numerical results ................................ 164
6.1 Basic assumptions ...................................................................................... 164
6.2 Traffic generation ..................................•................................................... 165
6.2.1 Binomial and Poisson distributions ...................................................... 166
6.2.2 Random traffic generation and confidence intervals ............................ 170
6.2.2.1 Transient phase .............................................................................. 171
6.2.2.2 Method of independent replications and batch means ................... 172
6.3 Network topology ...................................................................................... 174
6.3.1 Randomly generated graphs ................................................................. 176
6.4 Shortest path algorithms revisited ........................................................... 179
6.5 Wavelength routing without service-specific requirements ................... 180
6.5.1 Benefits of wavelength shifting ............................................................ 181
6.5.1.1 Network load ................................................................................. 182
6.5.1.2 Number of wavelengths ................................................................. 183
6.5.1.3 Connectivity .................................................................................. 184
6.5.1.4 Network size .................................................................................. 186
x
6.5.1.5 Topology ....................................................................................... 187
6.5.1.6 Influence of load correlation .......................................................... 190
6.5.1.7 Sparse wavelength shifting ............................................................ 194
6.5.1.8 Final remarks regarding wavelength shifting ................................ 197
6.6 Service-specific wavelength routing ......................................................... 199
6.6.1 Regular network operation ................................................................... 200
6.6.2 Service restorability .............................................................................. 212
7 Conclusions and future work ......•.•................•..................................... 224
8 References and further reading ............................................................ 226
9 Abbreviations ........................................................................................... 237
10 Index ....................................................................................................... 240
