Multiservice Networks Research Articles

Application-Oriented Flow Control: Fundamentals, Algorithms and Fairness

This paper is concerned with flow control and resource allocation problems in computer networks in which real-time applications may have hard quality of service (QoS) requirements. Recent optimal flow control approaches are unable to deal with these problems since QoS utility functions generally do not satisfy the strict concavity condition in real-time applications. For elastic traffic, we show that bandwidth allocations using the existing optimal flow control strategy can be quite unfair. If we consider different QoS requirements among network users, it may be undesirable to allocate bandwidth simply according to the traditional max-min fairness or proportional fairness. Instead, a network should have the ability to allocate bandwidth resources to various users, addressing their real utility requirements. For these reasons, this paper proposes a new distributed flow control algorithm for multiservice networks, where the application's utility is only assumed to be continuously increasing over the available bandwidth. In this, we show that the algorithm converges, and that at convergence, the utility achieved by each application is well balanced in a proportionally (or max-min) fair manner

Converged services over MPLS

As network traffic showed explosive growth in the 1990s, layer 2 services became a significant revenue source for providers. Unfortunately, since technology development did not progress in a timely and synchronized manner, many providers now need to manage multiple that are optimized for different services (voice, ATM, IP, etc.). In addition, these may share part of their resources in a layered manner, adding one network on top of the other one (e.g., IP over ATM), which results in overly complicated operation and inefficient use of network resources. Multiprotocol label switching provides a scalable solution for evolving providers' multiple service networks into a unified multiservice network. To make this transition happen, the one critical evolutionary process necessary is to carry the existing layer 1 TDM and layer 2 (ATM, frame relay, and Ethernet) traffic across MPLS core networks. This has been made possible by standardization work in the Internet Engineering Task Force (http://www.ictf.org), and has been successfully deployed by a number of providers around the world. In this article the pre-MPLS methods of network operation for multiple services are addressed, followed by an introduction to MPLS, and the layer 1 and layer 2 over MPLS architecture is provided in detail

A New Multiobjective Dynamic Routing Method for Multiservice Networks: Modelling and Performance

There are potential advantages in formulating the routing problems in modern multiservice networks as multiple objective problems. This paper presents a novel hierarchical bi-level multiobjective dynamic routing model for multiservice networks. It is based on a bi-objective shortest path algorithm, with dynamically adapted soft-constraints, to compute alternative paths for each node pair and on a heuristic to synchronously select alternative routing plans for the network in a dynamic alternative routing context. It is a routing method which periodically changes alternative paths as a function of periodic updates of certain QoS related parameters obtained from real-time measurements. The performance of the proposed routing method is compared with two reference dynamic routing methods namely RTNR and DAR by means of a discrete-event simulator.

Construction of the model and algorithms to estimate the throughput characteristics of the multiservice section of communication network with allowance for repeated calls

A model of a section of the multiservice communication network was constructed with allowance for the possibility of repeating a call that was blocked because of insufficient channel resource either in the section itself or at the subsequent segments of the load route including occupancy of the called device. For the proposed model and some of its important special cases, precise and approximate algorithms to estimate the main throughput characteristics were constructed. Solutions of some problems that are of interest from the standpoint of practical use of the results obtained were considered.

Cross-layer multiservice opportunistic scheduling for wireless networks

We consider opportunistic communication in multiservice wireless data networks using centralized controllers. Opportunistic scheduling (OS) is an emerging cross-layer media access control design approach to multiuser communication over fading wireless channels. OS exploits channel variations to maximize wireless throughput. We present a general background of OS schemes and then propose an OS scheme making an optimum trade-off between throughput and fairness, while maintaining stability in different channel environments and guaranteeing minimum service to multiple queues active concurrently at a given user

Distributed Admission Control in Multiservice IP Networks: Concurrency Issues

In distributed admission control (AC) schemes, handling concurrent AC decisions assumes a relevant role in avoiding over or false acceptance and, consequently, service quality degradation. This problematic is even more intricate in multiservice network environments where distinct service levels need to be fulfilled. This paper debates and points out solutions to mitigate the negativeimpact that distributed admission of flows might have on the service level guarantees provided to network customers. Keeping in mind that simplicity is a key factor for deployable AC solutions, we suggest and discuss the use of (i) a service-dependent concurrency index; (ii) a token-based system and (iii) a rate-based credit system, as alternative or complementary proposals to minimize or solve QoS degradation resulting from AC false acceptance.

Security architecture for IP-based multi-service networks

The telecommunications industry's transition to Internet Protocol (IP)-based networks is exciting and cost effective, but it also introduces new challenges for service providers, particularly as they begin to integrate Web services with communication services. Security is one key area that poses a significant challenge for service providers while at the same time providing opportunities for vendors. Because these new networks will have a number of service enablers and enriched services will be offered, application and user identity security becomes a chief concern. This paper focuses on IP-based services security architecture for evolving wireless and public domain networks, especially where Web services are brought into play. A Security Assertion Markup Language (SAML) is a basis for the security architecture, which incorporates federated architecture, authentication, encryption, and digital rights management. The paper also details a blended service scenario, highlighting enforcement of security at different entry points in the network.

An Analysis of a Unified Pricing Model for Multiservice Networks

There has been recent interest in employing unified pricing schemes for supporting both quality-of-service (QoS) and best-effort traffic within multiservice networks. This article presents an analytical approach for the design and analysis of this class of network pricing control. In particular, the authors propose an approximation method to estimate overall user value arising from all traffic types, given the routes for QoS traffic. Their approach considers admission control as both a resource allocation issue and a pricing control decision for QoS traffic in a combined QoS and best-effort environment. The authors show how to convert the price-based admission control decision to a resource-based blocking problem. The experimental results showed that the proposed analytical model is quite accurate as compared to simulation results. The authors also present the numerical results of performance analysis for multiservice networks using their proposed approximation method. Their approach can be used to predict the performance and parameter settings for a wide range of combined QoS and best-effort pricing schemes.

State-dependent call admission control in hierarchical wireless multiservice networks

State-dependent call admission control (SDCAC) is proposed to make efficient use of scarce wireless resource in a hierarchical wireless network with heterogeneous traffic. With SDCAC, new calls are accepted according to an acceptance probability taking account of not only cell dwell time but also call holding time and system state (i.e., occupied bandwidth). An analytical method is developed to calculate performance measures of interest, e.g., new call blocking probability, forced termination probability, overall weighted blocking probability. Numerical results with not only stationary but nonstationary traffic loads are presented to show the robustness of SDCAC. It is shown that SDCAC performs much better than the other considered schemes under nonstationary traffic load.

Multidomain Network Based on Programmable Networks: Security Architecture

This paper proposes a generic security architecture designed for a multidomain and multiservice network based on programmable networks. The multiservice network allows users of an IP network to run programmable services using programmable nodes located in the architecture of the network. The programmable nodes execute codes to process active packets, which can carry user data and control information. The multiservice network model defined here considers the more pragmatic trends in programmable networks. In this scenario, new security risks that do not appear in traditional IP networks become visible. These new risks are as a result of the execution of code in the programmable nodes and the processing of the active packets. The proposed security architecture is based on symmetric cryptography in the critical process, combined with an efficient manner of distributing the symmetric keys. Another important contribution has been to scale the security architecture to a multidomain scenario in a single and efficient way.

A new joint packet scheduling/admission control framework for multi-service wireless networks

Quality of service (QoS) provision is an important and indispensable function for multi-service wireless networks. In this paper, we present a new scheduling/admission control framework, including an efficient rate-guaranteed opportunistic scheduling (ROS) scheme and a coordinated admission control (ROS-CAC) policy to support statistic QoS guarantee in multi-service wireless networks. Based on our proposed mathematical model, we derive the probability distribution function (PDF) of queue length under ROS and deduce the packet loss rate (PLR) for individual flows. The new admission control policy makes admission decision for a new incoming flow to ensure that the PLR requirements of all flows (including the new flow) are satisfied. The numerical results based on ns-2 simulations demonstrate the effectiveness of the new joint packet scheduling/admission control framework.

21CN: networks and systems for BT in the 21st century [network architecture

The 21st century network and systems project or "21CN" as it is known at the British Telecom, is targeted at delivering an improved customer experience. It is a radical approach that touches all areas of BT networks, systems, and applications. In this article, the authors provide an overview of the 21CN architecture. The paper outlines the drivers and the architecture of this approach and indicates the benefits that it aims to deliver. The architecture is based on convergence to a single multiservice network controlled by a by a mobility-enabled intelligence layer supported by a much more flexible set of operational support. Applying the architecture leads to an improved customer experience, faster service provision, and radical cost reduction.

A framework for understanding network intelligence

The term network intelligence is widely used in the field of communication networks. A number of new and potentially limiting concepts and products based on the concept of network intelligence have been introduced, including smart flows, intelligent routing, and intelligent web switching. Many intelligent systems focus on a specific service, function, or device, and do not provide true end-to-end network intelligence. True network intelligence requires more than a set of disconnected elements; it requires an interconnecting and functionally coupled architecture that enables the various functional levels to interact and communicate with each other. We propose a uniform framework for understanding end-to-end communication network intelligence (CNI), which is defined as the ability of a network to act appropriately in a changing environment. We consider an appropriate action to be one that increases the optimal and efficient use of network resources in delivering services, and we define success as the achievement of behavior subgoals that support the service provider's ultimate goals, which are defined external to the network system. The framework presented incorporates the functional elements of intelligence into computational modules and interconnects the modules into networks and hierarchies that have spatial, logical, and temporal properties. Based on the framework proposed, we describe an end-to-end multiservice network application spanning the network management layer, optical layer, switching/routing layer, services layer, and other layers.

Efficiency and quality of service issues in MPLS transport for the UMTS access network

Multiprotocol Label Switching (MPLS) offers a simple and flexible transport solution for multiservice networks, and many operators are currently using or considering the use of an MPLS backbone. In UMTS networks, MPLS can be used both in the access part (i.e. the links that provide connectivity to each base station) and in the core. However, the efficient transport of short voice and data packets in the UMTS access network requires multiplexing and segmentation functions not provided by MPLS. This paper investigates the use of ATM Adaptation Layer 2 (AAL2) over MPLS to perform both functions. The efficiency of AAL2/MPLS is analyzed for different traffic types and compared with other transport options. The results indicate that significant capacity savings can be obtained with this solution.

Comments on "Optimal Resource Allocation in Multiservice CDMA Networks

In this note, counterexamples to Proposition 2 in the above-mentioned paper are presented, and a correct proof of Proposition 3 is given.

Design and Evaluation of a QoS-aware Framework for HIPERLAN/2 Networks

Recent advances on wireless technology are enabling the design and deployment of multiservice wireless networks. In order to be able to meet the QoS requirements of the various applications, it is essential to deploy QoS provisioning mechanisms. In this paper, we present a QoS framework to support various types of services in a wireless networking environment. Under this QoS framework, we propose various resource request mechanisms. We carry out a comparative study of the proposed schemes. Our simulation results show the effectiveness of the mechanisms when supporting different services, such as video, voice, best-effort and background traffic.

A framework for end-to-end deterministic-delay service provisioning in multiservice packet networks

The problem of providing end-to-end delay guarantees for deterministic-delay services in multiservice packet networks is addressed through a combination of dynamic resource reservation and routing. Our model is based on using rate-controlled earliest-deadline-first (RC-EDF) for providing hard bounds on end-to-end delays. With RC-EDF, a certain delay bound has to be allocated for a connection at each node in the selected path. The most commonly used resource reservation policy is uniform allocation which is based on dividing the end-to-end delay bound equally among the nodes in the selected path. This simple allocation policy could lead to nonuniform resource loading and subsequently lead to high blocking rates. Moreover, the most commonly used routing method is shortest-path first routing which is known to lead to network hotspots. We propose a set of dynamic nonuniform resource reservation policies and dynamic routing methods. One of the routing methods is the well-known widest-shortest path method and the other is a dynamic routing method that adaptively adjusts link costs and uses a similar algorithm to shortest-path routing (e.g., Dijkstra's algorithm). We show that for both uniform and nonuniform traffic loading of some example network topologies that the combination of the proposed resource reservation policies and dynamic routing can lead to significant reduction in the connection blocking ratio in all loading conditions except for excessively high loads.

A New Access Control Solution for a Multi-Provider Wireless Environment

The fundamental goal in future 4G mobile multi-service networks is to provide an efficient mobile computing environment. We presume that future terminals will be equipped with multiple heterogeneous wireless interfaces. We want to enable each user to seamlessly move between different providers' networks. Besides seamless roaming, a key consideration is also devoted to quality-of-service provision. In this article, we propose a model and an architectural framework for supporting quality of service in the context of interconnected multi-provider wireless systems. The proposed integrated COPS-based management and RADIUS-based access control architecture will allow providers to offer multimedia services while optimizing the use of the underlying network resources. We suggest new concepts and protocols to provide solutions to these challenges and describe the French national research project named MMQoS aiming on building such future networks.

The Open Mobile Alliance and trends in supporting the mobile services industry

The Open Mobile Alliance (OMA) is the leading industry forum for generating market-driven specifications for interoperable mobile service enablers to facilitate global user adoption of mobile multimedia services. Since its formation in 2002, the OMA has made significant progress in delivering several enablers in areas such as mobile Web services, push-to-talk over cellular, and presence, and it plans to deliver many more enablers in the coming years. This paper discusses the various projects undertaken by the OMA working groups that deal with multiservice networks and offers an early perspective on the mapping and evolution of the OMA enablers that are part of the overall OMA service environment (OSE), which spans all mobile access and core network technologies. The ideas presented in this paper are solely those of the authors; they do not reflect an official OMA point of view.

Integrating and managing converged multiservice networks

Balancing the conflicting practices of the “one service-one technology” and “one technology for all services” paradigms is a significant challenge. In response to this challenge, the telecommunications industry is shifting to a converged network paradigm based on Multiprotocol Label Switching (MPLS). MPLS can support multiple services over one infrastructure, thereby increasing flexibility and providing economies of scale. This paper examines two generic approaches to building a converged MPLS core. Based on our assessment of the advantages and challenges associated with these two approaches, we propose that carriers implement a distributed architecture to migrate to MPLS and scale existing layer 2 services. This paper discusses the technical merits of this architecture, which include high scalability, investment protection, multivendor interoperability, and rapid service introduction. It also describes how carriers can preserve quality of service (QoS) and service level agreements (SLAs) through the MPLS core. Finally, it describes a service-centric network management model that makes use of existing operation systems.