Signalling end-to-end optical services over multi-domain networks

This paper proposes a new UCLP (User-Controlled LightPath) architecture that offers end-to-end optical services provisioning in a multi-domain network. It also shows the experimental results of our UCLP software tool implemented on the Canarie optical network testbed. This work is motivated by the growing need for end-to-end lightpaths to support high volume data transferring applications such as GridFTP (GRID File Transfer Protocol) and SAN (Storage Area Networks) over multi-domain networks. The main problems encountred while provisioning end-to-end optical service in a multi-domain network are investigated and a review of the different interdomain signalling approaches is provided in comparison with our user-controlled lightpath provisioning approach. Various interdomain signalling approaches are discussed and compared to justify the necessity of signalling methods at the application level for long-duration applications.     

Routing with end-to-end QoS guarantees in broadband networks

We consider routing schemes for connections with end-to-end delay requirements, and investigate several fundamental problems. First, we focus on networks which employ rate-based schedulers and, hence, map delay guarantees into nodal rate guarantees, as done with the guaranteed service class proposed for the Internet. We consider first the basic problem of identifying a feasible route for the connection, for which a straightforward yet computationally costly solution exists. Accordingly, we establish several approximation schemes that offer substantially lower computational complexity. We then consider the more general problem of optimizing the route choice in terms of balancing loads and accommodating multiple connections, for which we formulate and validate several optimal algorithms. We discuss the implementation of such schemes in the context of link-state and distance-vector protocols. Next, we consider the fundamental problem of constrained path optimization. This problem, typical of quality of service routing, is NP-hard. While standard approximation methods exist, their complexity may often be prohibitive in terms of scalability. Such approximations do not make use of the particular properties of large-scale networks, such as the face that the path selection process is typically presented with a hierarchical, aggregated topology. By exploiting the structure of such topologies, we obtain an ϵ-optimal algorithm for the constrained shortest-path problem, which offers a substantial improvement in terms of scalability     

End-to-end QoS provisioning in mobile heterogeneous networks

The remarkable advances in information technologies bring a heterogeneous environment for mobile users and service providers. This heterogeneity exists in wireless access technologies, networks, user terminals, applications, service providers, and so on. The ability to provide seamless and adaptive quality of service in such a heterogeneous environment is key to the success of next-generation wireless communications systems. There has been a considerable amount of QoS research recently. However, the main part of this research has been in the context of individual architectural components, and much less progress has been made in addressing the issue of an overall QoS architecture for the mobile Internet. This article first summarizes the state-of-the-art QoS techniques and standardization activities, then examines in detail important challenges in building a ubiquitous QoS framework over the heterogeneous environment, and finally proposes a QoS framework integrating a three-plane network infrastructure and a unified terminal cross-layer adaptation platform to provide seamless support for future applications.     

End-to-end QoS framework for heterogeneous wired-cum-wireless networks

With information access becoming more and more ubiquitous, there is a need for providing QoS support for communication that spans wired and wireless networks. For the wired side, RSVP/SBM has been widely accepted as a flow reservation scheme in IEEE 802 style LANs. Thus, it would be desirable to investigate the integration of RSVP and a flow reservation scheme in wireless LANs, as an end-to-end solution for QoS guarantee in wired-cum-wireless networks. For this purpose, we propose WRESV, a lightweight RSVP-like flow reservation and admission control scheme for IEEE 802.11 wireless LANs. Using WRESV, wired/wireless integration can be easily implemented by cross-layer interaction at the Access Point. Main components of the integration are RSVP-WRESV parameter mapping and the initiation of new reservation messages, depending on where senders/receivers are located. In addition, to support smooth roaming of mobile users among different basic service sets (BSS), we devise an efficient handoff scheme that considers both the flow rate demand and network resource availability for continuous QoS support. Furthermore, various optimizations for supporting multicast session and QoS re-negotiation are proposed for better performance improvement. Extensive simulation results show that the proposed scheme is promising in enriching the QoS support of multimedia applications in heterogeneous wired-cum-wireless networks. Ming Li received his B.S. and M.S. in Engineering from Shanghai Jiao Tong University, China, in 1995 and 1998, respectively. He is currently a Ph.D. candidate in department of Computer Science, University of Texas at Dallas, where he received M.S. degree in Computer Science in Dec. 2001. His research interest includes QoSschemes for mobile ad-hoc networks and multimedia over wireless networks. Hua Zhu received the Ph.D. degree in Electrical Engineering from the University of Texas at Dallas, Texas. Since 2005, he has been working for San Diego Research Center, Inc., San Diego, CA, as a Research Engineer. His research interests include all layers of wireless communication systems. His particular interest is in L2/3 air interface design, performance analysis, and optimization for ad hoc and sensor networks. Imrich Chlamtac is the President of CREATE-NET and the Bruno Kessler Professor at the University of Trento, Italy. He has held various honorary and chaired professorships in USA and Europe including the Distinguished Chair in Telecommunications Professorship at the University of Texas at Dallas, Sackler Professroship at Tel Aviv University and has been on faculty at Technion, and UMass. Dr. Imrich Chlamtac has made significant contribution to various networking technologies as scientist, educator and entrepreneur. Dr. Chlamtac is the recipient of multiple awards and recognitions including Fellow of the IEEE, Fellow of the ACM, Fulbright Scholar, the ACM Award for Outstanding Contributions to Research on Mobility and the IEEE Award for Outstanding Technical Contributions to Wireless Personal Communications. Dr. Chlamtac published over three hundred and fifty refereed journal, book, and conference articles and is the co-author of four books. Dr. Chlamtac has widely contributed to the scientific community as founder and Chair of ACM Sigmobile, founder and steering committee chair of some of the lead conferences in networking including Mobicom, OptiComm, Mobiquitous, Broadnets, Securecomm. Dr. Chlamtac also serves as the founding Editor in Chief of the ACM/URSI/Springer Wireless Networks (WINET), the ACM/Springer Journal on Special Topics in Mobile Networks and Applications (MONET). B. Prahbakaran is with the faculty of Computer Science Department, University of Texas at Dallas. He has been working in the area of multimedia systems: animation & multimedia databases, authoring & presentation, resource management, and scalable web-based multimedia presentation servers. Dr. Prabhakaran received the prestigious National Science Foundation (NSF) CAREER Award in 2003 for his proposal on Animation Databases. He has published several research papers in various refereed conferences and journals in this area. He has served as guest-editor (special issue on Multimedia Authoring and Presentation) for ACM Multimedia Systems journal. He is also serving on the editorial board of Multimedia Tools and Applications journal, Kluwer Academic Publishers. He has also served as program committee member on several multimedia conferences and workshops. B. Prabhakaran has served as a visiting research faculty with the Department of Computer Science, University of Maryland, College Park. He also served as a faculty in the Department of Computer Science, National University of Singapore as well as in the Indian Institute of Technology, Madras, India.     

An enhanced backward recursive PCE-based computation scheme for end-to-end disjoint paths in multi-domain networks

To efficiently provide two disjoint end-to-end paths for working and protecting in multi-domain networks is challenging the network industry. The Backward Recursive PCE-based parallel approach (PA) for disjoint paths can achieve best computation performance at high cost of computation complexity and communication overhead. In this paper, we propose an enhanced PA (EPA), based on a no-differentiated in-BNs pair strategy to decrease the computation complex and communication overhead. The simulation results show that the EPA scheme can effectively reduce the computation and communication overhead.     

A flexible and distributed architecture for adaptive end-to-end QoS provisioning in next-generation networks

A novel distributed end-to-end quality-of-service (QoS) provisioning architecture based on the concept of decoupling the end-to-end QoS provisioning from the service provisioning at routers in the differentiated service (DiffServ) network is proposed. The main objective of this architecture is to enhance the QoS granularity and flexibility offered in the DiffServ network model and improve both the network resource utilization and user benefits. The proposed architecture consists of a new endpoint admission control referred to as explicit endpoint admission control at the user side, the service vector which allows a data flow to choose different services at different routers along its data path, and a packet marking architecture and algorithm at the router side. The achievable performance of the proposed approach is studied, and the corresponding results demonstrate that the proposed mechanism can have better service differentiation capability and lower request dropping probability than the integrated service over DiffServ schemes. Furthermore, it is shown that it preserves a friendly networking environment for conventional transmission control protocol flows and maintains the simplicity feature of the DiffServ network model.     

Node delay assignment strategies to support end-to-end delay requirements in heterogeneous networks

In a complex, heterogeneous network environment, such as the Internet, packets traversing different networks may be subjected to different treatments and may face different traffic loads across the routing path. This paper addresses the key issue of how to assign delay budgets to each network node along the routing path so that the end-to-end delay requirements of the supported applications are met. First, we describe a methodology to compute for a given flow a set of feasible per-node delays for the class of delay-based servers. We then formalize an optimal per-node delay assignment problem which takes into consideration the workload across the routing path. The solution, for homogeneous and heterogeneous networks, is provided. The resulting solution is optimal, but its implementation overhead is relatively high. To overcome this shortcoming, we propose two heuristics, EPH() and LBH(), to approximate the optimal strategy. EPH() uses the equi-partition concept to compute initial delay values and adjust these delay values to meet the end-to-end delay requirements. LBH() uses a relaxation factor to distribute the load proportionally across all nodes on the routing path. A simulation-based comparative analysis shows that the heuristics perform closely to the optimal schemes.     

端到端QoS的实现研究

对IP网的QoS研究导致了两种不同的QoS体系结构的出现：综合服务模型和区分服务模型。本文简单地介绍了这两种服务模型,分析了他们之间的优缺点和差异,详细讨论了如何从实际使用的角度结合两者的优势实现端到端QoS的方案。     

Admission control for QoS support in heterogeneous 4G wireless networks

Admission control plays a very important role in wireless systems, as it is one of the basic mechanisms for ensuring the quality of service offered to users. Based on the available network resources, it estimates the impact of adding or dropping a new session request. In both 2G and 3G systems, admission control refers to a single network. As we are moving towards heterogeneous wireless networks referred to as systems beyond 3G or 4G, admission control will need to deal with many heterogeneous networks and admit new sessions to a network that is most appropriate to supply the requested QoS. In this article we present the fundamentals of access-network-based admission control, an overview of the existing admission control algorithms for 2G and 3G networks, and finally give the design of a new admission control algorithm suitable for future 4G networks and specifically influenced by the objectives of the European WINNER project.     

Joint resource allocation with QoS provisioning in K-tier heterogeneous cellular networks

In this paper, the joint resource allocation （RA） problem with quality of service （QoS） provisioning in downlink heterogeneous cellular networks （HCN） is studied. To fully exploit the network capacity, the HCN is modeled as a K-tier cellular network where each tier＇s base stations （BSs） have different properties. However, deploying numbers of low power nodes （LPNs） which share the same frequency band with macrocell generates severe inter-cell interference. Enhancement of system capacity is restricted for inter-cell interference. Therefore, a feasible RA scheme has to be developed to fully exploit the resource efficiency. Under the constraint of inter-cell interference, we formulate the RA problem as a mixed integer programming problem. To solve the optimization problem we develop a two-stage solution. An integer subchannel assignment algorithm and Lagrangian-based power allocation algorithm are designed. In addition, the biasing factor is also considered and the caused influence on system capacity is evaluated. Simulation results show that the proposed algorithms achieve a good tradeoff between network capacity and interference. Moreover, the average network efficiency is highly improved and the outage probability is also decreased.     

Delay sensitive scheduling schemes for heterogeneous QoS over wireless networks

Future wireless networks will support the growing demands of heterogeneous and delay sensitive applications. In this paper, a users' satisfaction factor (USF) is defined to quantify quality of service (QoS) for different types of services such as voice, data, and multimedia, as well as for different delay constraints. This USF not only predicts the final delivered QoS during transmission, but also take advantages of the fact that different packets can be decoded at different time in the receivers. Based on this USF, four types of scheduling schemes considering tradeoffs between system performance and individual fairness are proposed. These schemes explore the time, channel, and multi-user diversity to guarantee quality of service and enhance the network performance. From the simulation results, the proposed scheduling schemes achieve different tradeoffs between individual fairness and high system performance for the heterogeneous and delay sensitive applications, compared with the weighted round-robin and the modified proportional fairness scheduling schemes     

UMTS中实现端到端QoS技术的研究

本文从Internet的QoS角度出发,着重分析了UMTS内的QoS技术和实现UMTS端到端QoS所需要的关键技术。     

Engineering end-to-end IP resilience usingresilience-differentiated QoS

Network resilience is becoming a key issue in the design of IP-based multimedia and multiservice networks. The current discussion about IP network resilience centers around MPLS-based recovery mechanisms. Any well designed recovery strategy has to take into account the different resilience requirements of the single traffic flows in order to avoid excessive usage of bandwidth for standby links. Faced with multiple recovery options, an ISP or NSP must decide which flows to protect to what extent against network failures. In this article an extension to existing quality of service (QoS) architectures is presented that integrates the signaling of resilience requirements with the traditional QoS signaling. We refer to this extended QoS model as resilience-differentiated QoS (RD-QoS). At the border of MPLS domains, the resilience requirements can then be directly mapped to the appropriate MPLS recovery options. A traffic engineering process for the provisioning of the resilience classes is introduced, and a case study demonstrates the significant network capacity savings achievable via this approach     

COPS-SLS usage for dynamic policy-based QoS management over heterogeneous IP networks

While each IP domain can deploy its own strategy to manage network resources, multimedia traffic needs end-to-end QoS management to obtain an overall service level. The provision of end-to-end QoS over a heterogeneous environment implies the negotiation of a mutually acceptable SLA. This article presents the use of the COPS-SLS protocol as a generic protocol for automatic service-level negotiation and the integration of this protocol in an overall QoS management architecture to manage service levels over multiple domains deploying different QoS technologies.     

P-cycle Protection in multi-domain optical networks

Providing resilient inter-domain connections in multi-domain optical GMPLS networks is a challenge. On the one hand, the integration of different GMPLS domains to run traffic engineering operations requires the development of a framework for inter-domain routing and control of connections, while keeping the internal structure and available resources of the domains undisclosed to the other operators. On the other hand, the definition of mechanisms to take advantage of such automatically switched inter-domain connectivity is still an open issue. This article focuses on the analysis of applicability of one of these mechanisms: P-cycle-based protection. The proposed solution is based on the decomposition of the multi-domain resilience problem into two sub-problems, namely, the higher level inter-domain protection and the lower level intra-domain protection. Building a P-cycle at the higher level is accomplished by certain tasks at the lower level, including straddling link connection, capacity allocation and path selection. In this article, we present several methods to realize inter-domain P-cycle protection at both levels and we evaluate their performance in terms of availability and spent resources. A discussion on a proposal of implementation of signalling based on extensions of existing protocols such as RSVP-TE and the PCE architecture illustrates the practical viability of the approach.

Routing scalability in multi-domain DWDM networks

This paper studies routing scalability in multi-domain DWDM networks. Although inter-domain provisioning has been well studied for packet/cell-switching networks, the wavelength dimension (along with wavelength conversion) poses many challenges in multi-domain DWDM settings. To address these concerns a detailed GMPLS-based hierarchical routing framework is proposed for multi-domain DWDM networks with wavelength conversion. This solution uses mesh topology abstraction schemes to hide domain-internal state. However related inter-domain routing loads can be significant here, growing by the square of the number of border nodes. To address these scalability limitations, improved inter-domain routing update strategies are also proposed and the associated performance of inter-domain lightpath RWA and signaling schemes studied.