Resource assignment for integrated services in wireless ATM networks

The task of supporting integrated multirate multimedia traffic in a bandwidth-poor wireless environment poses a significant challenge for network designers. In this paper we propose a novel bandwidth allocation strategy which partitions the available bandwidth amongst the different traffic classes in a manner that ensures quality-of-service guarantees for digital video while minimizing the maximum blocking probability for voice and data connections. At the connection level, near-optimum utilization of the reserved bandwidth for video traffic is achieved through an intra-frame statistical multiplexing algorithm, while at the system level the delicate task of partitioning the bandwidth between voice, video and data is accomplished by developing an efficient algorithm which uses traffic parameters consisting only of the aggregate traffic load and the total available bandwidth. The algorithm, built on non-trivial mathematical results is robust, easy to implement and has a geometric rate of convergence which ensures that the partitioning points are found quickly. These properties make it well suited for practical implementations, even for cases where changes in the aggregate traffic loads cause bandwidth allocations to be recomputed frequently. © 1998 John Wiley & Sons, Ltd.     

综合业务接入ATM网络的资源共享

本文提出了一种在ATM网络中传输综合业务的资源共享方案,该方案中,每一VP只传输一类业务,并根据各业务的带宽,各VP传输的业务量和链路的剩余带宽动态分配各个VP占用的宽带,在保证各类业务呼损率的前提下,可获得提高传输效率和降低节点归一化处理负荷的良好折衷。本文还引入了迟滞和资源预留两个概念,并分析了它们对呼损率和节点的归一化处理负荷的影响,最后给出了详细的理论分析和计算机模拟结果。     

A novel approach to provision differentiated services in survivable IP-over-WDM networks

IP-over-WDM networks are starting to replace legacy telecommunications infrastructure and they form a promising solution for next-generation networks (NGNs). Survivability of an IP-over-WDM network is gaining increasing interest from both the Internet research community and service providers (SPs). We consider a novel static bandwidth-provisioning algorithm to support differentiated services in a survivable IP-over-WDM network. We propose and investigate the characteristics of both integer linear program (ILP) and heuristic approaches to solve this problem. In the heuristic method, we propose backup reprovisioning to ensure network resilience against single-node or multiple-link failures. Illustrative examples compare and evaluate the performance of the two methods in terms of capacity-usage efficiency and computation time.     

ATM passive optical networks and integrated VDSL

VDSL offers a cost effective solution for the provision of a full-service broadband access network. Standards are emerging that will define the line code, duplexing method, and spectrum requirements for VDSL. VDSL chipsets and modules are becoming available that allow the technology to be evaluated in the field. This article describes the architecture and hardware integration that has been performed in integrating VDSL technology into an ATM PON system     

Traffic characterization for integrated services networks

A discrete-time queuing analysis is presented for integration of multiple traffic types in a packet-switched TDM (time-division multiplexing) system. The correlation of each traffic type is represented in terms of the power spectral density. The general expression obtained for the aggregate mean queue size indicates that slowly varying traffic types exert the largest effect on the queuing process. Also, a lengthy-steady traffic is highly predictable. An adaptive flow control and routing scheme, based on signal prediction, which successively adjusts the short-burst traffic arrival rate at each TDM node, is introduced and analyzed. The analytical results indicate a substantial reduction in the correlation effect on the system queuing behavior     

A differentiated optical services model for WDM networks

This article addresses the issues of scalable end-to-end QoS in metropolitan DWDM networks serving as transit networks for IP access networks. DWDM offering a few wavelengths has been deployed in the past in backbone networks to upgrade point-to-point transmission where sharing is based on coarse granularity. This type of DWDM backbone network, offering a few light-paths, provides no support for QoS services traversing the network. As DWDM networks with larger numbers of wavelengths penetrate the data-centric metro environment, specific IP service requirements such as priority restoration, scalability, dynamic provisioning of capacity and routes, and support for coarse-grain QoS capabilities will have to be addressed in the optical domain in order to achieve end-to-end QoS over a DWDM network. We propose a QoS service model in the optical domain called differentiated optical services (DoS) based on a set of optical parameters that captures the quality and reliability of the optical lightpath     

Some optimal traffic regulation schemes for ATM networks: a Markovdecision approach

Some new traffic regulation schemes are defined in terms of a relief-spacing (or spacing of the allowance for cell delivery to the network) function. The class of open-loop traffic regulators (TR's) is defined in terms of relief-spacing functions which depend on some user-state; this class may be viewed as an extension of the Spacer-Controller defined in terms of some constant (user-state independent) relief-function. The optimal open-loop TR's are derived by formulating proper optimization problems and applying a Markov decision approach. Numerical results illustrate the improved performance of the optimal open-loop TR over that of the (constant relief-spacing) Spacer-Controller. Finally, the class of closed-loop TR's is defined in terms of relief-spacing functions which depend on both some user- and some network-state information and its optimal element is derived. The improved performance under the optimal closed-loop TR over that of the optimal open-loop TR is illustrated and their difference determines the performance gain if feedback information can become available on time     

A policy framework for integrated and differentiated services inthe Internet

We examine the issues that arise in the definition, deployment, and management of policies related to QoS in an IP network. The article provides an overview of requirements for QoS policies, alternative policy architectures that can be deployed in a network, different protocols that can be used to exchange policy information, and exchange of policy information among different administrative domains. We discuss current issues being examined in IETF and other standards bodies, as well as issues explored in ongoing policy-related research at different universities and research laboratories     

Analysis of a discrete-time queue with integrated bursty inputs in ATM networks

In this paper, we carry out an exact analysis of a discrete-time queue system with a number of independent Markov modulated inputs in ATM networks, using a generating function approach. We assume that the queueing system has an infinite buffer with M servers. The cell arrival process is characterized by a number of independent Markov modulated geometrical batch arrival processes. We first obtain the generating function of the queue-size distribution at steady-state in vector form, then derive an expression for the average queue-size in terms of the unknown boundary probabilities. To obtain those unknown probabilities, we use the technique proposed in Reference 1. This involves decomposing the system characteristic function to evaluate the roots and solving a set of linear equations. One of the contributions of this paper is presented in Lemma 1, which characterizes the property of the underlying eigenvalues. For one special case of at least M-1 cell arrivals during one slot at one Markov state and of at least M arrivals at all other states, the determination of the unknowns is straightforward. If every Markov modulated arrival process can be further decomposed into a number of i.i.d. two-state, or three-state, or even four-state Markov modulated arrival processes, then each root can be obtained separately using an iterative algorithm. Numerical results are presented to validate the proposed traffic models against actual traffic measurements.     

The AGAVE approach for network virtualization: differentiated services delivery

This paper describes a new paradigm to realize network virtualization and defines two novel concepts, network planes and parallel Internets, to achieve service differentiation. These concepts are packaged in a technology-agnostic and a multi-dimensional approach for the delivery of Internet protocol (IP) service differentiation, both intra- and inter-domain. The definition of the aforementioned concepts covers several dimensions, mainly routing, forwarding, and traffic management ones. Unlike some radical “Post IP” proposals, this paper advocates an evolutionary approach for enhancing the level of experienced connectivity services (including quality of service and robustness) and therefore to enhance the Internet of the future. Both the rationale and the merits of our approach are explained. In addition, this paper focuses on the critical problem of determining the network planes and parallel Internets to be engineered by a given IP network provider to meet the service connectivity requirements of external service providers. Finally, in order to assess the validity of the proposed approach, a network plane Emulation Platform is described.     

Adaptive connection admission control for differentiated services access networks

In our earlier work, we have proposed some modifications for the bandwidth broker framework. With our modifications, it is possible to use measurement-based admission control in addition to the more traditional parameter-based admission control. Moreover, we have presented a new flexible admission control scheme that has proven to be very efficient in terms of bottleneck link utilization. Two problems, however, have arisen: the use of scheduling weights in admission control and bursty connection arrivals. In this paper, we present that the former one can be dealt with the use of adaptive scheduling weights, while the latter one can be fought with adaptive reservation limits. The proposed new algorithms are validated through simulations and their performance is compared against the nonadaptive basic scheme.     

Scalable flow control for multicast ABR services in ATM networks

We propose a flow-control scheme for multicast ABR services in ATM networks. At the heart of the proposed scheme is an optimal second-order rate control algorithm, called the α-control, designed to deal with the variation in RM-cell round-trip time (RTT) resulting from dynamic drift of the bottleneck in a multicast tree. Applying two-dimensional rate control, the proposed scheme makes the rate process converge to the available bandwidth of the connection's most congested link sensed by the traffic source. It also confines the buffer occupancy to a target regime bounded by a finite buffer capacity as the system enters the equilibrium state. It works well irrespective of the topology of the multicast tree. Using the fluid analysis, we model the proposed scheme and analyze the system dynamics for multicast ABR traffic. We study the convergence properties and derive the optimal-control conditions for the α-control. The analytical results show that the scheme is stable and efficient in the sense that both the source rate and bottleneck queue length rapidly converge to a small neighborhood of the designated operating point. We present simulation results which verify the analytical observations. The simulation experiments also demonstrate the superiority of the proposed scheme to the other schemes in dealing with RM-cell RTT and link-bandwidth variations, achieving fairness in both buffer and bandwidth occupancies, and enhancing average throughput     

Explicit rate flow control for ABR services in ATM networks

We propose a novel explicit rate flow control algorithm intended for available-bit-rate (ABR) service on an ATM network subject to loss and fairness constraints. The goal is to guarantee low cell loss in order to avoid throughput collapse due to retransmission by higher level protocols. The mechanism draws on measuring the current queue length and bandwidth availability, as well as tracking the current number of active sessions contending for capacity, to adjust an explicit bound on the source transmission rates. We identify the factors that affect queue overflows and propose simple design rules aimed at achieving transmission with controlled loss in a dynamic environment. We also discuss how conservative design rules might be relaxed by accounting for statistical multiplexing in bandwidth sharing among bursty ABR sources and variable-bit-rate (VBR) sources     

INQIRE: a software approach to monitoring QoS in ATM networks

Unlike traditional best-effort packet networks, ATM networks support a wide range of services by providing a specified QoS on each ATM connection. Currently, QoS can be measured with specialized high-speed testing equipment but their complexity and cost prevent them from wide field use. This article describes the INQIRE project approach based on software for enabling common personal computers (with an ATM network interface card) to function as QoS monitoring stations at the edges of an ATM network. The main objective is to develop a low-cost, off-the-shelf alternative to broadband testing equipment. An INQIRE station, consisting of a PC running the INQIRE application, can actively probe any selected connection and collect sample measurements of the QoS. The monitoring approach is intended to be non-intrusive and work with any ATM network without requiring any modifications to existing ATM switch equipment or interruptions to active services     

Global corporate communications with integrated services digital networks

This paper presents proposals and justification for standards governing the implementation of integrated service digital networks (ISDN). Using several programming protocols in a layered architecture provides continuing service during system evolution. The authors use a corporate communications environment for examples as the most probable initial implementation of the networks described. Some ISDN sites are operating, although not yet on a global scale, and present the building blocks for more advanced services in the near future. The authors present arguments supporting a concerted effort be started now to establish global standards for ISDN, so that design and development can comply in the most time-effective manner.     

A routing architecture for mobile integrated services networks

A drawback of the conventional Internet routing architecture is that its route computation and packet forwarding mechanisms are poorly integrated with congestion control mechanisms. Any datagram offered to the network is accepted; routers forward packets on a best-effort basis and react to congestion only after the network resources have already been wasted. A number of proposals improve on this to support multimedia applications; a promising example is the Integrated Services Packet Network (ISPN) architecture. However, these proposals are oriented to networks with fairly static topologies and rely on the same conventional Internet routing protocols to operate. This paper presents a routing architecture for mobile integrated services networks in which network nodes (routers) can move constantly while providing end-to-end performance guarantees. In the proposed connectionless routing architecture, packets are individually routed towards their destinations on a hop by hop basis. A packet intended for a given destination is allowed to enter the network if and only if there is at least one path of routers with enough resources to ensure its delivery within a finite time. Once a packet is accepted into the network, it is delivered to its destination, unless resource failures prevent it. Each router reserves resources for each active destination, rather than for each source–destination session, and forwards a received packet along one of multiple loop-free paths towards the destination. The resources and available paths for each destination are updated to adapt to congestion and topology changes. This mechanism could be extended to aggregate dissimilar flows as well. This revised version was published online in June 2006 with corrections to the Cover Date.     

Robust rate control for integrated services packet networks

Research on congestion-control algorithms has traditionally focused more on performance than on robustness of the closed-loop system to changes in network conditions. As the performance of the control loop is strictly connected with the quality of service, these systems are natural candidates to be approached by the optimal control theory. Unfortunately, this approach may fail in the presence of transmission delay variations, which are unavoidable in telecommunication systems. In this paper, we first show the fragility of optimal controllers and demonstrate their instability when the control delay is not known exactly. Then we propose a robust control algorithm based on a classical proportional integral derivative scheme which does not suffer from this fragility phenomenon. Its stability versus the control delay variations, as well as versus sources that transmit less than their computed share, is studied with Nyquist analysis. The control algorithm is implemented within a simulator in the framework of the asynchronous transfer mode (ATM) ABR transfer capability. The final part of the paper shows some selected results assessing the performance of the control algorithm in a realistic network environment. ABR was chosen as an example, but the control studied here can be applied in any data network to obtain a robust and reliable congestion-control scheme.