http://www.sciencedirect.com/science/article/B6TYP-46RDF5H-2/1/4d892d8249d5d0271e6b0a8dc9bd23a

Boavida, F.

Solé-Pareta, J.

Estudo Geral

Editorial
Guest editorial
The current Internet popularity and growth impose the
necessity of optimal usage of network resources. Moreover,
the increasing demand for services with different Quality of
Service (QoS) requirements, together with the progressive
increase in traffic volumes, imposes a re-definition of Inter-
net capabilities. This aim can only be achieved through open
international co-operation of both engineering, lead by the
IETF, and academic efforts. The COST Action 263 aims at
the coordination, from a European perspective, of concerted
actions among participating organisations and research
groups active in the field of the Quality of future Internet
Services (QofIS), with the QofIS workshop being its main
scientific event. COST sponsorship is also used for other
existing events to give them the appropriate focus.
The COST 263 Action participates in QofIS relevant
clustering of IST projects, and establishes contacts with
European and other International bodies. Among others,
COST 263 is supporting initiatives to create a QofIS
Network of Excellence within the sixth Framework
Programme, maintains active contacts with Eurescom,
IETF, TMF, Internet2, Qbone, TF-NGN, etc. monitors and
helps disseminating further ongoing practical work in the
IST QoS cluster comprised of Aquila, Tequila, Cadenus,
M3I, Long, and other relevant projects.
COST 263 created the framework for an annual interna-
tional workshop on QofIS, now a relevant international
conference on QoS for the Internet. The first QofIS work-
shop (QofIS’00) was held in Berlin (Germany) on Septem-
ber 25, 2000. The second workshop (QofIS’02) took place
in Coimbra (Portugal) in September 24–26, 2001; while the
third workshop will be held in Zurich (Switzerland) on
October 16–18, 2002. The following QofIS’03 is already
scheduled to be held in Kista (Sweden). The workshop
proceedings are published by Springer in Lecture Notes in
Computer Science series and are distributed at the event.
Based on the workshop outcome and on the need to deepen
certain topics from a more focussed perspective, COST 263
has accepted the kind invitation of Computer Communica-
tions Journal to prepare a special issue.
This Special Issue is devoted to the best papers presented
at the Second International Workshop on Quality of future
Internet Services, QofIS’01, held in Coimbra. All QofIS’01
authors were asked to produce extended and updated
versions of their papers and to submit them to a selection
process for publication in this Special Issue. After this selec-
tion process, from the 22 papers presented at QofIS’01,
eight of them were finally accepted (35% acceptance ratio).
These eight papers plus two invited papers are included in
this Special Issue. These papers cover QoS routing, capacity
admission control (CAC) methods, differentiated services
(DiffServ) networks, traffic engineering strategies, applica-
tion design issues, and charging and billing in the Internet.
In the paper An Analytical Design of Optimal Playout
Schedulers for Packet Video Receivers, the authors address
the trade-off that must be considered when designing packet
video receivers. An analytical model that captures stream
continuity and stream latency behaviours in best effort
networks is used to analyse the performance gains of the
optimal playout scheduler.
The paper On Call Admission Control for IP Telephony in
Best Effort Networks, proposes a CAC solution to cope with
the trade-off between efficient utilisation of bandwidth and
implementation complexity to support voice communica-
tion with acceptable quality over best effort IP networks,
without e.g. DiffServ mechanisms.
One approach for supporting service differentiation,
which is followed by the DiffServ architecture, is to add
mechanisms inside the network routers. Drawbacks of this
approach are the increased complexity, compared with the
Internet today. An alternative approach can be based on
installing a simple congestion mechanism in the network,
such as Explicit Congestion Notification (ECN) marking,
that informs users of the congestion cost their traffic is
incurring. The paper Service Differentiation in ECN
Networks using Weighted-Based Congestion Control for
various Packet Marking Algorithms, investigates the service
differentiation in terms of average throughput and achieved
performance using a weighted window-based congestion
control.
In the paper A Framework for Providing Differentiated
QoS Guarantees in IP-based Networks, the authors describe
the admission control and resource management mechan-
isms together with network services implemented in the
pilot network of the IST AQUILA project. Special emphasis
is given to the implementation of traffic classes. The
described mechanisms operate at time scales that range
from the long and medium term down to packet-level
scheduling.
Computer Communications 26 (2003) 291–293
0140-3664/02/$ - see front matter q 2002 Elsevier Science B.V. All rights reserved.
PII: S0140-3664(02)00148-2
www.elsevier.com/locate/comcom
The paper The Two Markers System for TCP and UDP
Flows in a Differentiated Services Network proposes a
marking scheme that considers both the TCP dynamics
and the interaction of TCP and UDP traffic in DiffServ
networks. The use of two markers, one at TCP sources to
control the dynamics of TCP flows, and another at the edge
of DiffServ domains to fairly mark aggregate flows, is
discussed and analysed.
In the paper The TCP Control Block Interdependence in
Fixed Networks—New Performance Results, the authors
explore the use of information collected from existing
TCP connections in order to initialise control variables of
new TCP connections. The paper investigates and compares
two TCP control block interdependence algorithms along
with their performance and fairness gains.
The motivation for the problem addressed in the paper
Profile-Based Routing and Traffic Engineering, arises from
the needs of service providers who must dynamically
reserve bandwidth guaranteed routes in carrier’s and ISPs’
networks. This paper presents a new algorithm and frame-
work for dynamic routing of bandwidth-guaranteed flows.
The paper On the Complexity of QoS Routing presents an
exact QoS routing algorithm and analyses its complexity for
various cases. The focal point of the paper is not the
proposed algorithm itself but the complexity of QoS rout-
ing. In the general case of additive link weights, QoS routing
is an NP-complete problem, that is, a problem that is unsol-
vable in practical terms. The paper, however, presents argu-
ments that point to the fact that in the majority of realistic
networks the QoS routing problem is not NP-complete and,
thus, is feasible.
The two invited papers included in this Special Issue,
respectively, deal with two of the hottest topics in next
generation Internet, namely Route and Resource Manage-
ment, and Charging and Pricing.
The first invited paper is entitled A New Traffic Engineer-
ing Manager for DiffServ/MPLS Networks: Design and
Implementation on an IP QoS Testbed, and proposes the
TEAM tool (a Traffic Engineering Automated Manager),
which is designed to provide a novel and unique architecture
capable of managing large scale MPLS/DiffServ networks.
The second invited paper, entitled A Market-Managed
Multi-service Internet, describes an approach to managing
QoS using pricing, which also allows open innovation for
providers through their tariffs and for customers in their use
of the network for new applications. This paper presents a
broad picture of the achievements of the Market Managed
Multi-service Internet (M3I) IST project.
This Special Issue ends with a short note on the keynote
speech presented at the QofIS’2001 workshop by Roberto
Sabatino. In this note the author presents the SEQUIN
project, which involves eight partners in seven countries
and is co-funded by the European Commission under the
Information Society Technologies (IST) Programme. The
objective of SEQUIN is to define and implement an end-
to-end approach to Quality of Service (QoS) across the pan-
European network for research, GEANT, and the National
Research and Education Networks (NRENs) that connect to
GEANT.
As a final remark, the guest editors would like to thank all
the reviewers for their effort in putting together this Special
Issue, namely Arturo Azcorra, Burkhard Stiller, Chirdeep
Chhabra, David Hutchison, Dimitrios N. Serpanos,
Edmundo Monteiro, Georg Carle, Gonc¸alo Quadros, Guil-
laume Urvoy-Keller, Gunnar Karlsson, Ian Marsh, Ioannis
Stavrakakis, Jordi Domingo-Pascual, Jorge S. Silva, Marı´lia
Oliveira, Martina Zitterbart, Mihai Popa, Mike Devetsikio-
tis, Mikhail Smirnov, Milena Janic, Nabil Benameur,
Olivier Bonaventure, Piet Van Mieghem, Ramin Hekmat,
Sugih Jamin, and Yevgeni Koucheryavy. A special thank is
due to Mikhail Smirnow, chairman of COST 263, who
enthusiastically supported not only the work on this Special
Issue of Computer Communications, but also all COST 263
activities.
F. Boavidaa,*
J. Sole´-Paretab
aDepartamento de Engenharia Informa´tica, Universidade
de Coimbra, Po´lo II Pinhal de Coimbra, 3030-290
Coimbra, Portugal
E-mail address: boavida@dei.uc.pt
bDepartament d’Arquitectura de Computadors, Universitat
Polite`cnica de Catalunya, Jordi Girona, 1-3, Mo`dul D6
(Campus Nord), 08034
Barcelona, Catalunya, Spain
E-mail address: pareta@ac.upc.es
14 May 2002
F. Boavida, J. Sole´-Pareta / Computer Communications 26 (2003) 291–293292
* Corresponding author.
F. Boavida, J. Sole´-Pareta / Computer Communications 26 (2003) 291–293 293
Fernando Boavida received his PhD in Infor-
matics Engineering in 1990, and he currently is
an Associate Professor at the Department of
Informatics Engineeing (DEI) of the Faculty of
Sciences and Technology of the University of
Coimbra. He is the leader of the Laboratory of
Communications and Telematics of DEI and the
President of the Computing Centre of the
University of Coimbra. His main research intests
are Multimedia Distributed Systems and Quality
of Service in Communications Systems. He was
the chairman of the Program Committee of QofIS’2001—Second Inter-
national Workshop on Quality of future Internet Services. His publica-
tions include one book, three book chapters, and over 20 papers in
national conferences and 55 papers in international refereed journals
and conferences. He participated in European initiatives such as RARE
(Re´seaux IP Europe´enes), EWOS (European Workshop for Open
Systems) and COST 263. He is a member of ACM and of IEEE, and
he is a licensed Professional Engineer. He is a member of the Editorial
Advisory Board for Computer Communications. His homepage is at
http://www.dei.uc.pt/~boavida.
Josep Sole´-Pareta was awarded his Master’s
degree in Telecommunication Engineering in
1984, and his PhD in Computer Science in
1991, both from the Universitat Polite`cnica de
Catalunya (UPC). In 1984 he joined the Compu-
ter Architecture Department of UPC. Since 1992
he has been an Associate Professor with this
department. He spent the summers of 1993 and
1994 at the Georgia Institute of Technology. He
has participated in the Spanish R&D
Programme for the development of the Broad-
band Communications in Spain (PLANBA). He is co-founder and
member of the Advanced Broadband Communications Centre of UPC
(http://www.ccaba.upc.es). His current research interests are in Broad-
band Internet, High-Speed and Optical Networks, with emphasis on
traffic engineering, traffic characterisation, traffic management and
QoS provisioning. He has participated in INFOWIN, MICC and
IMMP ACTS projects, and currently is participating in LION, DAVID
and LONG IST projects. He was a member of the Infocom’98 Program
Committee, and currently is member of the program committee of the
QofIS workshop, which is annually organized by the COST 263 Action.
He is a member of the IEEE.


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