A Foundation for Stochastic Bandwidth Estimation of Networks with Random Service

We develop a stochastic foundation for bandwidth estimation of networks with random service, where bandwidth availability is expressed in terms of bounding functions with a defined violation probability. Exploiting properties of a stochastic max-plus algebra and system theory, the task of bandwidth estimation is formulated as inferring an unknown bounding function from measurements of probing traffic. We derive an estimation methodology that is based on iterative constant rate probes. Our solution provides evidence for the utility of packet trains for bandwidth estimation in the presence of variable cross traffic. Taking advantage of statistical methods, we show how our estimation method can be realized in practice, with adaptive train lengths of probe packets, probing rates, and replicated measurements required to achieve both high accuracy and confidence levels. We evaluate our method in a controlled testbed network, where we show the impact of cross traffic variability on the time-scales of service availability, and provide a comparison with existing bandwidth estimation tools

An Iterated Game of Uncoordinated Sharing of Licensed Spectrum Using Zero-Determinant Strategies

We consider private commons for secondary sharing of licensed spectrum bands with no access coordination provided by the primary license holder. In such environments, heterogeneity in demand patterns of the secondary users can lead to constant changes in the interference levels, and thus can be a source of volatility to the utilities of the users. In this paper, we consider secondary users to be service providers that provide downlink services. We formulate the spectrum sharing problem as a non-cooperative iterated game of power control where service providers change their power levels to fix their long-term average rates at utility-maximizing values. First, we show that in any iterated 2x2 game, the structure of the single-stage game dictates the degree of control that a service provider can exert on the long-term outcome of the game. Then we show that if service providers use binary actions either to access or not to access the channel at any round of the game, then the long-term rate can be fixed regardless of the strategy of the opponent. We identify these rates and show that they can be achieved using mixed Markovian strategies that will be clearly identified in the paper

A note on statistical multiplexing and scheduling in video networks at high data rates

This paper comments on the impact of link scheduling and statistical multiplexing on the multiplexing gain at high data rates. The multiplexing gain is evaluated using the number of MPEG video traces that can be provisioned with delay guarantees on a network link. The presented data indicates that, at high transmission rates, the multiplexing gain is substantial and is dominated by the e ects of statistical multiplexing

A Min-Plus System Interpretation of Bandwidth Estimation

Abstract — Significant research has been dedicated to methods that estimate the available bandwidth in a network from traffic measurements. While estimation methods abound, less progress has been made on achieving a foundational understanding of the bandwidth estimation problem. In this paper, we develop a min-plus system theoretic formulation of bandwidth estimation. We show that the problem as well as previously proposed solutions can be concisely described and derived using min-plus system theory, thus establishing the existence of a strong link between network calculus and network probing methods. We relate difficulties in network probing to potential non-linearities of the underlying systems, and provide a justification for the distinctive treatment of FIFO scheduling in network probing. I

1 A Calculus for End-to-end Statistical Service Guarantees

Abstract — The deterministic network calculus offers an elegant framework for determining delays and backlog in a network with deterministic service guarantees to individual traffic flows. A drawback of the deterministic network calculus is that it only provides worst-case bounds. Here we present a network calculus for statistical service guarantees, which can exploit the statistical multiplexing gain of sources. We introduce the notion of an effective service curve as a probabilistic bound on the service received by an individual flow, and construct an effective service curve for a network where capacities are provisioned exclusively to aggregates of flows. Numerical examples demonstrate that the calculus is able to extract a significant amount of multiplexing gain in networks with a large number of flows. I

The QoSbox: A PC-Router for Quantitative Service Differentiation in IP Networks

We describe the design and implementation in UNIX-based PCs of the QoSbox, a configurable IP router that provides per-hop service guarantees on loss, delays and throughput to classes of traffic. There is no restriction on the number of classes or the specific service guarantees each class obtains. The novel aspects of the QoSbox are that (1) the QoSbox does not rely on any external component (e.g., no traffic shaping and no admission control) to enforce the desired service guarantees, but instead, (2) dynamically adapts packet forwarding and dropping decisions as a function of the instantaneous traffic arrivals; also, (3) the QoSbox can enforce both absolute bounds and proportional service guarantees on queueing delays, loss rates, and throughput at the same time. We evaluate the QoSbox in a testbed of PC-routers over a FastEthernet network, and show that the QoSbox is a possible solution allowing for incremental deployment to the problem of providing service differentiation in a scalable manner

A Scalable Service Architecture for Providing Strong Service Guarantees

For the past decade, a lot of Internet research has been devoted to providing different levels of service to applications. Initial proposals for service differentiation provided strong service guarantees, with strict bounds on delays, loss rates, and throughput, but required high overhead in terms of computational complexity and memory, both of which raise scalability concerns. Recently, the interest has shifted to service architectures with low overhead. However, these newer service architectures only provide weak service guarantees, which do not always address the needs of applications. In this paper, we describe a service architecture that supports strong service guarantees, can be implemented with low computational complexity, and only requires to maintain little state information. A key mechanism of the proposed service architecture is that it addresses scheduling and buffer management in a single algorithm. The presented architecture offers no solution for controlling the amount of traffic that enters the network. Instead, we plan on exploiting feedback mechanisms of TCP congestion control algorithms for the purpose of regulating the traffic entering the network

Workconserving vs. Non-workconserving Packet Scheduling: An Issue Revisited

Many packet schedulers for QoS networks are equipped with a rate control mechanism. The function of a rate control mechanism (rate controller) is to buffer packets from flows which exceed their negotiated traffc profile. It has been established that rate controllers lead to reduced buffer requirements at packet switches, and do not increase the worst-case delays in a deterministic service. On the other hand, rate controllers make a scheduler non-workconserving, and, thus, may yield higher average end-to-end delays. In this study, we show that by properly modifying a rate controller, one can design a scheduler which balances buffer requirements against average delays. We present a scheduler, called Earliness-based Earliest Deadline First (EEDF), which achieves such a balancing using a tunable rate control mechanism. In simulation experiments, we compare EEDF with a rate-controlled EDF scheduler and a workconserving version of EDF

Dissemination of Address Bindings in Multi-substrate Overlay Networks

Abstract—Self-organizing overlay networks have emerged as a new paradigm for providing network services. While most overlay networks are built over a single substrate network (mostly, the Internet), recently the construction of overlay networks over multiple heterogeneous substrate networks has received increased attention. Such networks seek to interconnect mobile or fixed devices using a diverse set of networking modalities. Here, a key challenge arises from the more complex address bindings, where a single logical identifier is bound to multiple substrate addresses. In this paper, we evaluate the design and inherent trade-offs of mechanisms for exchanging information on address bindings in a multi-substrate overlay network. The evaluation is done using measurement experiments of an overlay network software system. The measurement data provides insights into the scalability of dissemination methods. An important finding is that gossip-based address dissemination is less effective than an on-demand dissemination of address bindings. I

A QoS Architecture for Quantitative Service Differentiation

For the past decade, a lot of Internet research has been devoted to providing different levels of service to applications. Initial proposals for service differentiation provided strong service guarantees, with strict per-flow bounds on delays, loss rates, and throughput, but required high overhead in terms of computational complexity and memory, both of which raise scalability concerns. Recently, the interest has shifted to class-based service architectures with low overhead. However, these newer service architectures only provide weak service guarantees, which do not always address the needs of applications. In this article, we introduce a service architecture that supports strong per-class service guarantees, can be implemented with low computational complexity, and only requires to maintain little state information. A ke