Policing Mechanism Research Articles

Thresholds: On the Need for Frame Discarding in Cell-Switched Networks

This paper introduces a novel policing mechanism, called Packet Leaky Bucket in which all cells of a frame are marked with the same level of priority. Moreover, it discusses the need for having a frame discard mechanism in cell-switched networks when frame-oriented policing mechanisms are used.

Managing Soft Security Threats: Current Progress and Future Prospects

This concluding essay explores the development of the concept of security since the end of the Cold War, in a world characterized by failing states, and the rise of non-state actors. It revisits the competing paradigms of ‘The End of History’ and ‘The Clash of Civilisations’ within globalization trends as a whole, and security in particular. Post September 11, 2001, the boundaries between hard and soft security have been blurred as the relationship between terrorism and illegal trade have become apparent. The paper highlights three challenging processes of particular relevance for soft security: the still growing gap between rich and poor; the technological revolution; and the changing role of and attitudes to military force. Environmental, economic and population pressures elsewhere fuel the soft security threats in Europe, and the problems cannot be solved by improved policing or border mechanisms alone. Rather, the solution lies in treating them at a global level.

In the Shadow of the State: The Politics of Denunciation and Panegyric during the Trujillo Regime in the Dominican Republic, 1940-1958

In the Shadow of the State: The Politics of Denunciation and Panegyric during the Trujillo Regime in the Dominican Republic, 1940-1958

On the performance of generalized processor sharing servers under long-range dependent traffic

This paper introduces the computation of delay and backlog bounds for a generalized processor sharing (GPS) server under long-range dependent (LRD) traffic. The traffic is supposed to be regulated by the Fractal Leaky Bucket policing mechanism, which is an appropriate regulator for LRD traffic. Results are extended to a network of GPS servers with arbitrary topology, and the stability of those networks is analysed.

FR-ATM 연동에서 Frame Relay 트래픽 통합 감시제어 방안

A FR-ATM interworking function that has FR and ATM interfaces, should guarantee the QoS of both frame relay and ATM networks. The IWF requires the policing mechanisms for FR and ATM respectively, and needs to map the traffic parameters each other. In this case, traffic parameter mapping and policing function are performed independently. In the aspect of FR traffic policing, this function degrades processor performance if it is worked by software, or includes additional hardware function. The best way to solve this is to integrate this function into ATM function because ATM is performed by well defined hardware already. In this paper we propose the integrated traffic control mechanism. That is, frames are segmented to cells first, and then policing mechanism is applied to the cells to guarantee the FR QoS. Therefore proper policing algorithm is essential to the integrated FR traffic mechanism. The evaluations are done with simulations in comparison of existing FR algorithms, ATM VBR and GFR policing algorithms, and the proposed algorithm.

Dynamic resource management considering the real behavior of aggregate traffic

This paper explains why the theory of effective bandwidth is in general not applicable to characterize realistic traffic sources. Moreover, we show that a static allocation of network resources (bandwidth and/or buffer space) based on large deviation theory can be highly inefficient when the real statistical behavior of traffic is taken into account. As an alternative, we propose a dynamic resource management scheme based on prediction techniques. As a specific example, we apply this scheme to a Differentiated Service (DiffServ) Internet environment, in which the goal, besides policing the incoming traffic, is to optimize the use of network resources, thus minimizing the probability of occurrence of violations of contract guarantees. The performance of the proposed scheme is evaluated via simulations and our results show the superior performance of the new algorithm in terms of buffer overflows, output link utilization, and jitter, as compared to currently used policing and shaping mechanisms.

Worker policing in the bee Apis florea

Apis florea is a single-combed, open-nesting, dwarf honeybee indigenous to Asia. In common with other species of this genus, A. florea is highly polyandrous, and is therefore predicted to curtail worker reproduction by mutual policing mechanisms that keep worker reproduction at an extremely low level. Policing mechanisms could involve destruction of workers' eggs or offspring, or aggression toward those workers that are reproductively active. We show that in A. florea, worker-laid eggs are eliminated approximately twice as fast as queen-laid eggs, indicating that A. florea uses oophagy of worker-laid eggs as a mechanism of worker policing. Genetic analysis of four colonies indicated that all males produced were sons of queens, not workers. Dissections of 800 workers, from four colonies, did not reveal any significant levels of ovary activation. These results suggest that worker policing is an effective component of the mechanisms that maintain worker sterility in this species. Furthermore, they suggest that worker policing via oophagy of worker-laid eggs is pleisiomorphic for the genus.

The effects of correlated arrivals at a server with credit‐based traffic policing

AbstractIn this paper we observe the steady state and transient behaviour of correlated cell arrivals into a server with credit‐based traffic policing. We derive expressions for the lag‐k correlations of the departure process from the traffic policing mechanism, and observe how dependencies in the departure stream affect cell loss at the server. The results illustrate the impact of the second‐order statistics and the higher moments of the cell arrival processes on the traffic policing mechanism performance. Copyright © 2001 John Wiley & Sons, Ltd.

Rate control for VBR video over ATM: simplification and implementation

Rate control is essential to ensure high-quality video transmission over asynchronous transfer mode (ATM) networks; both source and channel rates must not violate buffer or network traffic constraints in order to guarantee decoded video quality. To date, source and channel rate selection has been performed jointly because the rates are related through buffer and network constraints and therefore appear to be interdependent. It is shown that selection of these rates can be separated and the rate control problem is therefore simplified, allowing sequential source and channel rate selection without the need for iteration. A rate control algorithm is proposed which implements noniterative, separate sequential selection of source and channel rates in order to minimize the distortion variation between frames, subject to all buffer and network constraints. In particular, the leaky bucket is used as the traffic policing mechanism. Achieving a target rate for individual frames is facilitated by using a rate-distortion optimized video coder which allows coding to an exactly specified rate or distortion. Channel rate selection is performed following source rate selection with the goal of providing smooth traffic to the network, thereby allowing a high statistical multiplexing gain. Experiments demonstrate that the proposed noniterative rate control algorithm, when implemented using the optimized coder, achieves consistent video quality while providing smooth traffic to the network.

Policing method for Markovian traffic descriptors of VBR MPEG sources over ATM networks

An efficient policing mechanism for Markov model-based traffic descriptors of VBR MPEG video traffic is proposed. A VBR video sequence is described by a set of traffic descriptors using a scene-based Markov model for effective resource allocation and accurate QoS prediction. To monitor the input traffic from the source, the authors have defined a set of a limited number of representative monitoring parameters and also defined an exponential bounding function in order to accommodate dynamic behaviour. The simulation results show that the proposed policing mechanism for Markovian traffic descriptors monitors sophisticated traffic, such as MPEG video, effectively and also protects network resources from both malicious and abnormally behaved traffic.

An Overview of Congestion Control Techniques in ATM Networks and Some Performance Results

ATM is a high speed multiplexing and switching technique used for multimedia communication. Efficient congestion control and prevention schemes for packet switched networks need to be designed for their effective and stable operation. Their design becomes particularly critical in ATM networks due to the high link speed, diverse traffic characteristics and requirements of QOS.In this paper we have reviewed and compared the congestion control and prevention schemes for ATM networks on the basis of simulation results. There are basically two types of schemes namely, The Open Loop or Preventive Control and The Closed Loop or Reactive Control. The Open Loop or Preventive control schemes allow a call to be accepted only if enough network resources are available. In case an admitted call violates the negotiated parameters strict police action is taken. We have simulated all the proposed policing mechanisms and the results show that Open loop congestion control schemes are suitable for CBR arid VBR traffic which are delay sensitive services, because their performance degrades rapidly for bursty traffic. No permanent bandwidth allocation is made in the closed loop or reactive control schemes prior to call setup. Rather the bandwidth made available to each call is varied dynamically depending on the degree of congestion, thus making these schemes unsuitable for delay sensitive services. The Closed loop or Reactive control schemes are more effective for ABR traffic, because it is delay insensitive.

On the equivalent bandwidth of self-similar sources

This article presents a method for the computation of the equivalent bandwidth of an aggregate of heterogeneous self-similar sources, as well as the time scales of interest for queueing systems fed by a fractal Brownian motion (fBm) process. Moreover, the fractal leaky bucket, a novel policing mechanism capable of accurately monitoring self-similar sources, is introduced.

Policing mechanism and cell loss priority control on voice cells in ATM networks using fuzzy logic

The authors present a fuzzy logic-based implementation of the policing mechanism (PM) and cell loss priority control (CLPC) functions on voice cells in asynchronous transfer mode (ATM) networks. Specifically, a redesigned model of fuzzy leaky bucket (FLB) is presented which serves as an alternative PM on the voice sources in an ATM network. As a continuation of the implementation of the FLB in the ATM network, three models of ATM switches with different algorithms are constructed, to perform CLPC on the voice cells, as well as to enhance the network throughput. Simulation results show that FLB is a better PM than the conventional leaky bucket (LB) in terms of cell loss probability and throughput while the mean transfer delay remains unchanged. It is also shown that the model of ATM switch with fuzzy token generator is the most balanced CLPC scheme as compared with the other two models.

V-NET: A versatile network architecture for flexible delay guarantees in real-time networks

This paper proposes a Versatile Network Architecture (V-NET) to support flexible delay guarantees for applications in real-time networks. Applications communicate over the V-NET by using end-to-end network connections which support real-time and reliability characteristics tailored to meet the application's specified requirements. V-NET differs from other proposed architectures in that, in addition to addressing the issue of quality of service (QoS) feasibility for a wide spectrum of real-time applications, it also provides a mechanism to determine a network state dependent range of feasible delay values at each switching node along the routing path. These delay ranges can be used to assign per-node delays that reflect the resource availability of the node, thereby reducing the likelihood of bottlenecks along the routing path. The V-NET delay guarantees are provided for a variety of packet scheduling algorithms and traffic policing mechanisms. This flexibility is an important design consideration as a real-time network architecture must accommodate existing and future multimedia applications, with hard-, soft-, and non-real-time traffic. The performance evaluation results demonstrate the efficiency of this scheme in handling different traffic scenarios and QoS requirements. We have shown that it is possible, and indeed efficient, to determine an upper-bound on the delay of real-time traffic, when using our per-node delay assignment policies.

Private Security in China: A Note on Recent Developments

China has initiated significant social and economic reforms. Although crime rates have remained constant, the creation of a market economy has stimulated private security enterprises. This paper examines the growth of these private initiatives, how they co-exist with state and traditional policing mechanisms, and the challenges of delivering internal security at a time of rapid, widespread changes. The structures are complex, and changing, but they are briefly discussed and some points are made about the type of lessons that are being learned as China moves towards a market economy.

Development and behaviour of anarchistic honeybees

Anarchistic honeybees result from extremely rare behavioural mutations which allow workers to lay eggs despite the presence of the queen. We investigated the behavioural development of bees derived from a line in which ca. 5% of workers have developed ovaries and lay viable eggs. Other than their developed ovaries and proclivity to lay eggs, the anarchistic workers we studied are apparently normal, performing normal worker-like behaviour. Unlike many laying workers in queenless colonies, they are not queen-like and are apparently not the objects of aggression. When day-old workers from anarchistic colonies were cross-fostered into anarchistic and wild-type host colonies, the frequency of ovary development was an order of magnitude higher in the anarchistic host (9.1%) than in the wild-type host (0.7%). This suggests that there is a policing mechanism that affects ovary development in honeybees. Thus, worker reproduction is probably suppressed at the level of ovary development as well as by oophagy of worker-laid eggs. Other mechanisms, such as aggression towards individuals with developed ovaries, may also exist, but we found no evidence for this.

On the impact of traffic control algorithms on resource management in ATM networks

Resource allocation algorithms in ATM networks operate on the basis of the value of certain source traffic descriptors and the extent to which the network resources are occupied. The different types of algorithms exhibit varying degrees of efficiency in estimating the resource to be allocated. However, the values any of them estimate will only be reliable if the traffic descriptors values remain, throughout the lifetime of the connections, the same as those negotiated in the call set-up phase. This can be guaranteed by a source traffic policing function which forces the traffic of any violating sources to respect the values negotiated. Unfortunately, a certain amount of excess traffic escapes the control of real policing mechanisms. This overloads the ATM switch for access to the network and consequently may cause an increase in the cell loss ratio. The article estimates the correction required by the CAC algorithm to avoid this risk. We compare two different policing mechanisms, one based on conventional logic and another on fuzzy logic, assessing the influence of their degree of selectivity on the additional bandwidth the CAC algorithm needs to reserve in order to guarantee the QoS requirements of all connections.

Characterisation of Singapore One ATM network

The statistics of cell loss at both burst and cell levels are studied by simulation based on the configuration of the Singapore One ATM network. A virtual connection through the Singapore One network is modelled as a tandem queueing network to which mixtures of homogeneous discrete-time burst–silence traffic with different burst lengths are offered. Attention is focused on a designated traffic stream as it goes through the tandem queueing network. In the simulation, the authors have not introduced the ‘independence assumption’ between the adjacent queues, i.e. the actual tandem queueing network is used to obtain the performance measures for the designated traffic stream. Cell loss probability and high-order cell loss distributions such as cell loss-free run distribution and cell loss pattern distribution are obtained. These results provide valuable information for the estimation of end-to-end overall quality of service (QoS), design of the cell policing mechanism and flow control schemes in the ATM networks.

A guaranteed-no-cells-dropped buffer management scheme with selective blocking for cell-switching networks

A guaranteed-no-cells-dropped buffer management scheme with selective blocking for cell-switching networks

LB-SELA: rate-based access control for ATM networks

The statistical multiplexing of sources with diverse traffic characteristics in ATM networks leads to serious congestion control problems. One of the most fundamental is the policing of sources, particularly those with bursty traffic characteristics. Because of the statistical nature of burstiness, the policing of these sources is difficult and the known policing mechanisms cannot control them effectively. In this paper, the Leaky Bucket mechanism is enhanced using a learning algorithm in order to “learn” the behaviour of the source. As will be shown in the simulation results, the tighter and faster control achieved by the proposed methodology results in more statistical gain and better guarantee of the QoS constraints.