Influence of GMPLS Recovery Mechanisms on TCP Performance

Optical networks based on wavelength-division-multiplexing (WDM) techniques are very likely to be omnipresent in future telecommunication networks. Those networks are deployed in order to face the steady growth of traffic, which is for a large part Internet related. In the resulting IP-over-WDM scenario, TCP/IP constitutes an important fraction of the traffic transported over these networks. As IP networks are becoming increasingly mission-critical, it is of the utmost importance that these networks (and hence the supporting transport networks) be able to recover quickly from failures such as cable breaks or equipment outages. To that end, several IP-over-WDM network scenarios and corresponding protection and restoration strategies have been devised. It is clear that some trade-offs will have to be made in order to choose an appropriate strategy. In this paper, we investigate the effects of such recovery actions on the behavior of TCP, being the ubiquitous protocol used by today's network users. We examine the influence of different parameters such as the speed of recovery actions, changing length of the routes followed by the client data (TCP flows), changes in available bandwidth, etc. Thereby, we focus on what the TCP end-users care about, i.e., the number of bytes transported end-to-end within a certain time interval.     

Intelligent optical networking for multilayer survivability

In recent years, telecommunication networks have faced explosive (IP) traffic growth. As traffic keeps growing, network reliability gains more and more importance. This article investigates to which extent switched connections and fast connection provisioning, typical for intelligent optical networks (IONs), can be used to provide resilience in an IP-over-optical multilayer network scenario. This solution, based on transport network flexibility, is compared with more traditional static multilayer resilience schemes in terms of cost (capacity) requirements and operational (dis)advantages     

Integrated routing in GMPLS-based IP/WDM networks

The Internet traffic evolution has forced network operators to migrate toward an integrated infrastructure which brings the IP and optical layers under a unified model. The integration between the two technologies has been facilitated by the development of the Generalized Multi Protocol Label Switching. In the integrated scenario, Multilayer Traffic Engineering can be reinforced with integrated routing techniques. Integrated IP/WDM routing facilitates the routing decision phase by allowing a node to have a complete knowledge of the IP and WDM domains when accommodating traffic. This study focuses on integrated IP/WDM routing. We analyze two basic policies widely discussed in literature: one policy prioritizes the traffic accommodation on the virtual topology, while the other prioritizes the traffic accommodation on the physical topology. We show that both the mechanisms do not lead to efficient resource utilization because they tend to congest one layer more than the other one. We propose an adaptive heuristic which combines the advantages of both the policies. When accommodating traffic, the proposed approach selects the appropriate layer depending on the resource utilization being experienced in the virtual and the physical topologies. We demonstrate via simulations that the cross-layer resource optimization executed by the proposed scheme achieves significant improvements in terms of blocking ratio.     

Scalable architectures for all-optical label swapping nodes

All-Optical Label Swapping (AOLS) nodes are believed to be part of the future networks. The original node designs, however, are very hard scalable. This article presents three alternatives that swap labels analogous to the original design. Two of the proposed new switches use the same all-optical technology to parallelly compare labels but, they divide fibres in data wavelengths that only transport payloads and label wavelengths that only transport labels. The third design sequentially compares the incoming label with addresses in the node available in order to make the routing decision. All three architectures are compared in terms of hardware necessary to perform routing.

Multilayer traffic engineering for multiservice environments

Multilayer traffic engineering (MLTE) serves to provide cross-layer online network optimization techniques to cope with rapid variations and short-term evolutions in traffic patterns. MLTE extends traffic engineering as it exists in IP/MPLS-based technology toward the multilayer IP/MPLS-over-optical transport network. In addition to the IP/MPLS traffic routing, MLTE exposes much larger adaptation flexibility by building on next-generation automatic switched optical transport networks. These offer fast setup and teardown of end-to-end multi-hop optical connections (lightpaths), which are offered to the IP/MPLS layer as dynamically provisioned capacity. This dynamic nature leads to an IP/MPLS logical topology that can be reconfigured on the fly, and IP/MPLS link capacity that can be up- or downgraded as client traffic demand varies. These MLTE techniques are generally used to increase perceived network performance in terms of throughput or QoS. As such, a MLTE-managed network offers a better than best-effort service. Many types of traditional and novel services are shifting toward IP/MPLS technology. Consequentially, MLTE algorithms and strategies should be conceived with the characteristics of such services in mind. We present a MLTE strategy that can be implemented in a robust and distributed way. This strategy is then taken as the starting point in a study which evaluates its suitability to such services. We show how the strategy can be adapted considering service performance metrics such as end-to-end delay, traffic loss, and routing stability, and how such service optimizations impact general MLTE objectives such as IP/MPLS logical topology mesh size reduction.

Flexible TDMA/WDMA passive optical network: Energy efficient next-generation optical access solution

Access networks must further advance to address the intensification of the requirements of growing speeds and the usage of Internet applications, and time and wavelength division multiple access (TDMA/WDMA) based passive optical networks (TWDM-PONs) have been widely considered as one of the evolutionary steps of next-generation optical access (NGOA) networks. TWDM-PON combines the flexibility of TDMA with an increased capacity offered by the use of a WDM layer. Moreover, it offers interesting and challenging avenues to minimize energy consumption: especially, with current access networks consuming about 80% of the energy consumed in the Internet. Along with other efforts, reducing energy consumption of central offices is conspicuous as it directly minimizes the operational expenditures of network providers. In this paper, we explore the new paradigms to conserve energy at the central offices in TWDM-PONs. By extensive simulations, we evaluate the possible energy savings in the various flavors of TWDM-PON. Based on the findings, we propose a new architectural flavor of TWDM-PON and benchmark the architecture for cost, power consumption and reach. We also propose a novel energy saving scheme for the proposed architecture and evaluate the impact of the proposed algorithm on energy savings by extensive simulations.     

Pan-European Optical Transport Networks: An Availability-based Comparison

The traffic to be carried by today's European backbone networks increases very rapidly. An important portion of this traffic consists of data traffic (mainly IP-related). In the future data traffic is expected to become the abundantly dominant traffic type, while voice traffic will only account for a very small portion of the total traffic volume. In this paper, some network topologies for such a pan-European fiber-optic backbone network are presented (more details can be found in [1]). These topologies are compared in terms of the efficiency of the network design both from a cost and capacity point of view and in terms of the availability of the connections routed over this network. In order to be able to assess the network topologies under realistic circumstances, the expected traffic demand is forecasted. This enables to make the comparison for the current traffic volume as well as for the traffic patterns of the future. As not all types of (data) traffic require the same degree of survivability and in order to leverage the total capacity cost of the network design, a distinction is made between different recovery options in the optical layer for the different traffic types considered.     

FAMOUS: A Network Architecture for Delivering Multimedia Services to FAst MOving USers

When today’s commuters in the train or in a car want to access the Internet, they see themselves restricted to simple web surfing or e-mail. Interactive multimedia services, like online gaming or video conferencing are still unavailable to them, even with promising new technologies like UMTS or WiMAX. The impact of high bit rate multimedia traffic on the access network and aggregation network is an important topic, that has not been addressed in enough detail before. We designed a network architecture for offering these multimedia services to fast moving users. We refer to the overall network architecture as the FAMOUS network architecture, which consists of two parts: (i) an access network part which has to deal with large number of users, asking for a high bandwidth, while experiencing a high handoff frequency and (ii) an aggregation network part which has to deal with dynamic tunnels of very high bandwidth, while experiencing a low handoff frequency. In this paper, we detail the FAMOUS architecture, together with optimized handoff strategies, an optical switching architecture, a design methodology for dimensioning aggregations networks and automatic tunnel pre-configuration and activation. Moreover, performance results of these mentioned aspects will be presented.Filip De Greve was born in Gent, Belgium, in 1978. He received his Master of Science degree in Electrotechnical Engineering from Ghent University, Gent, Belgium in 2001. In 2002, he joined the Department of Information Technology of the Faculty of Applied Sciences, University of Ghent as a doctoral researcher. Besides specific Ethernet-related research topics, his current research interests are related to broadband communication networks and include design, routing and reliability of access and aggregation networks.Bart Lannoo was born in Torhout, Belgium, in 1979. He received his Master of Science degree in Electrotechnical Engineering from Ghent University, Ghent, Belgium in 2002. Since August 2002, he has been working with Department of Information Technology (INTEC) of the Faculty of Applied Sciences, Ghent University as a doctoral researcher. His current research interests are in optical access networks, including both fixed access networks (FTTx) and optical access for wireless communication.Liesbeth Peters received the degree in Electrotechnical Engineering from Ghent University, Belgium in 2001. Since August 2001, she has been working as a doctoral researcher with the Department of Information Technology of Ghent University, where she joined the Broadband Communications Networks Group. Since October 2002, she works there as a research assistant of the Fund for Scientific Research – Flanders (F.W.O.-V., Belgium). Her current research interests are in broadband wireless communication and the support of IP mobility in wired cum wireless networks.Tom Van Leeuwen was born in Gent, Belgium, in 1979. He received his masters degree in Computer Engineering from the Ghent University, Gent, Belgium in 2002. Since 2002, he has been working with Department of Information Technology of Ghent University (INTEC) as a doctoral researcher. In 2004 he received a PhD grant from the Institute for the Promotion of Innovation through Science and Technology in Flanders (IWT-Vlaanderen). His current research interests are in broadband wireless communication.Frederic Van Quickenborne (M. Sc. Degree in Electrotechnical Engineering, University of Ghent, Belgium, 2002) published different papers on the growing importance of ethernet in aggregation and core networks. Besides his interest in ethernet related topics (QoS, VLANs, xSTP), he is also involved in projects concerning video-streaming and is working on a Click-based ethernet testbed. This research is funded by a PhD grant from the Institute for the Promotion of Innovation through Science and Technology in Flanders (IWT-Vlaanderen), that he obtained in 2004.Didier Colle received a M.Sc. degree in electrotechnical engineering (option: communications) from the Ghent University in 1997. Since then, he has been working at the same university as researcher in the department of Information Technology (INTEC). He is part of the research group INTEC Broadband Communication Networks (IBCN) headed by Prof.: Piet Demeester. His research lead to a Ph.D. degree in February 2002. From January 2003 on, he was granted a postdoctoral scholarship from the “Instituut voor de aanmoediging van Innovatie door Wetenschap en Technologie in Vlaanderen (IWT-Vlaanderen)”. His research deals with design and planning of communication networks. His work is focussing on optical transport networks, to support the next-generation Internet. Up till now, he has actively been involved in three IST projects (LION, OPTIMIST and DAVID) and in the COST266 action. His work has been published in more than 40 scientific publications in international conferences and journals.Filip de Turck received his M.Sc. degree in Electronic Engineering from the Ghent University, Belgium, in June 1997. In May 2002, he obtained the Ph.D. degree in Electronic Engineering from the same university. From October 1997 to September 2001, Filip De Turck was research assistant with the Fund for Scientific Research-Flanders, Belgium (F.W.O.-V.). At the moment, he is a part-time professor and a post-doctoral fellow of the F.W.O.-V., affiliated with the Department of Information Technology of the Ghent University. Filip De Turck is author or co-author of approximately 80 papers published in international journals or in the proceedings of international conferences. His main research interests include scalable software architectures for telecommunication network and service management, performance evaluation and optimization of routing, admission control and traffic management in telecommunication systems.Ingrid Moerman was born in Gent, Belgium, in 1965. She received the degree in Electro-technical Engineering and the Ph.D degree from the Ghent University, Gent, Belgium in 1987 and 1992, respectively. Since 1987, she has been with the Interuniversity Micro-Electronics Centre (IMEC) at the Department of Information Technology (INTEC) of the Ghent University, where she conducted research in the field of optoelectronics. In 1997, she became a permanent member of the Research Staff at IMEC. Since 2000 she is part-time professor at the Ghent University. Since 2001 she has switched her research domain to broadband communication networks. She is currently involved in the research and education on broadband mobile & wireless communication networks and on multimedia over IP. She is author or co-author of more than 300 publications in the field of optoelectronics and communication networks.Mario Pickavet received an M.Sc. and Ph.D. degree in electrical engineering, specialized in telecommunications, from Ghent University in 1996 and 1999, respectively. Since 2000, he is professor at Ghent University where he is teaching telecommunication networks and algorithm design. His current research interests are related to broadband communication networks (WDM, IP, (G-)MPLS, OPS, OBS) and include design, long-term planning and routing of core and access networks. In this context, he is currently involved a.o. in the European IST projects “All-Optical Label Swapping Employing Optical Logic Gates in Network Nodes” (LASAGNE) and “Optical Networks: Towards Bandwidth Manageability and Cost Efficiency” (e-Photon/ONe) and in several national research projects. He has published about a hundred international publications, both in journals (e.g. IEEE JSAC, IEEE Comm. Mag., JLT) and in proceedings of conferences. He is one of the authors of the book ‘Network Recovery: Protection and Restoration of Optical, SONET-SDH, IP, and MPLS’.Bart Dhoedt received a degree in Engineering from the Ghent University in 1990. In September 1990, he joined the Department of Information Technology of the Faculty of Applied Sciences, University of Ghent. His research, addressing the use of micro-optics to realize parallel free space optical interconnects, resulted in a PhD degree in 1995. After a 2 year post-doc in opto-electronics, he became professor at the Faculty of Applied Sciences, Department of Information Technology. Since then, he is responsible for several courses on algorithms, programming and software development. His research interests are software engineering and mobile & wireless communications. Bart Dhoedt is author or co-author of approximately 70 papers published in international journals or in the proceedings of international conferences. His current research addresses software technologies for communication networks, peer-to-peer networks, mobile networks and active networks.Piet Demeester finished his PhD thesis at the Department of Information Technology (INTEC) at the Ghent University in 1988. At the same department he became group leader of the activities on Metal Organic Vapour Phase Epitaxial growth for optoelectronic components. In 1992 he started a new research group on Broadband Communication Networks. The research in this field resulted in already more than 300 publications. In this research domain he was and is a member of several programme committees of international conferences, such as: ICCCN, the International Conference on Telecommunication Systems, OFC, ICC, and ECOC. He was Chairman of DRCN’98. In 2001 he was chairman of the Technical Programme Committee ECOC’01. He was Guest Editor of three special issues of the IEEE Communications Magazine. He is also a member of the Editorial Board of the Journals “Optical Networks Magazine” and ldquo;Photonic Network Communications”. He was a member of several national and international PhD thesis commissions. Piet Demeester is a member of IEEE (Senior Member), ACM and KVIV. His current research interests include: multilayer networks, Quality of Service (QoS) in IP-networks, mobile networks, access networks, grid computing, distributed software, network and service management and applications (supported by FWO-Vlaanderen, the BOF of the Ghent University, the IWT and the European Commission). Piet Demeester is currently full-time professor at the Ghent University, where he is teaching courses in Communication Networks. He has also been teaching in different international courses.     

A broad view on overspill routing in optical networks: a real synthesis of packet and circuit switching?

The emerging wavelength switched networks reduce the strain on packet forwarding. Unfortunately, that solution is not really efficient on a bandwidth level, and is not ideally suited for bursty traffic. Packet switched solutions, whether electronic or optical, can use statistical multiplexing to cope with bursty traffic and yield better bandwidth efficiency. We present a novel network concept that can combine these two worlds, withholding their advantages. We introduce this Overspill Routing In Optical Networks (ORION), and discuss several aspects of it: the overall architecture and network concept, node design and implementation, and evaluation at network level as well as node level.     

Overspill routing in optical networks: a true hybrid optical network design

To efficiently support the highly dynamic traffic patterns of the current Internet in large-scale switches, we propose a new hybrid optical network design: Overspill Routing In Optical Networks (ORION). By taking advantage of the reduced (electronic) processing requirements of all-optical wavelength switching, the electronic bottleneck is relieved. At the same time, ORION achieves a level of statistical multiplexing comparable to the more traditional point to point WDM solutions, circumventing the bandwidth inefficiencies of all-optical wavelength switched networks, caused by dynamic traffic patterns. The result is a true hybrid optical network design, forming a bridge between these two switching concepts. In this paper the generic concept of ORION is described. An example node design, based on current advanced optical technologies, is described in detail. The ORION concept is also evaluated, comparing it with its two composing technologies, optical wavelength switching and point to point WDM, as well as a third, more trivial, hybrid one, through several case studies.