Traffic Aggregation Research Articles

Implementing and Testing Priority Scheduler and Token Bucket Policer in differentiated Service

Internet applications are growing rapidly. The requirement of QoS by these applications varies from very lenient to strict. Maintaining QoS is one of the most typical and challenging task in such scenario. Differentiated services architecture is very popular in such scenario. Differentiated Services is a practical method to implement traffic based service differentiation works on traffic aggregation, per hop behaviour forwarding. Differentiated services uses classifiers to categorize traffic in to flows, policies are defined to allocate the resources to flows and policers are used to shape the bursty traffic whereas schedulers are used to forward the traffic from various traffic queues.

Energy-Efficient Baseband Unit Placement in a Fixed/Mobile Converged WDM Aggregation Network

Energy efficiency is expected to be a key design parameter for next-generation access/aggregation networks. Using a single network infrastructure to aggregate/backhaul both mobile and fixed network traffic, typically referred to as fixed/mobile convergence (FMC), seems a promising strategy to pursue energy efficiency. WDM networks are a prominent candidate to support next-generation FMC network architectures, as they provide huge capacity at relatively low costs and energy consumption. We consider a FMC WDM aggregation network in which the novel concept of “hotelling” of mobile baseband units (BBUs) is employed. The so-called BBU hotelling consists in separating BBUs from their cell sites and consolidating them in single locations, called hotels. As a result, the aggregation network will transport both IP (fixed and mobile) traffic and CPRI (fronthaul) traffic, the latter exchanged between each BBU and its cell site. In this paper, we propose an energy-efficient WDM aggregation network, and we formally define the BBU placement optimization problem, whose objective is to minimize the defined aggregation infrastructure power (AIP). We consider three different network architectures: Bypass, Opaque, and No-Hotel, which feature different placement of BBUs and routing of traffic. By modeling the power contributions of each active device, we study how and how much BBU consolidation, optical bypass, and active traffic aggregation influence the AIP, for all the three architectures. Our results show that, in our case study, the proposed architectures enable savings up to about 60%-65% in dense-urban/urban and about 40% in rural scenarios.

Multi‐granular, multi‐purpose and multi‐Gb/s monitoring on off‐the‐shelf systems

SUMMARYAs an attempt to make network managers’ life easier, we present M3Omon, a system architecture that helps to develop monitoring applications and perform network diagnosis. M3Omon behaves as an intermediate layer between the traffic and monitoring applications that provides advanced features, high performance and low cost. Such advanced features leverage a multi‐granular and multi‐purpose approach to the monitoring problem. Multi‐granular monitoring provides answers to tasks that use traffic aggregates to identify an event, and requires either flow records or packet data or even both to understand it and, eventually, take convenient countermeasures. M3Omon provides a simple API to access traffic simultaneously at several different granularities, i.e. packet‐level, flow‐level and aggregate statistics. The multi‐purposed design of M3Omon allows not only performing tasks in parallel that are specifically targeted to different traffic‐related purposes (e.g. traffic classification and intrusion detection) but also sharing granularities between applications, e.g. several concurrent applications fed from flow records that are provided by M3Omon. Finally, the low‐cost characteristic is brought by off‐the‐shelf systems (the combination of open‐source software and commodity hardware) and the high performance is achieved thanks to modifications in the standard NIC driver, low‐level hardware interaction, efficient memory management and programming optimization. Copyright © 2014 John Wiley & Sons, Ltd.

Exploring Bias in Traffic Data Aggregation Resulting from Transition of Traffic States

Transportation engineers and researchers heavily use traffic data, which are generally aggregated by predetermined time intervals (e.g., 5 to 15 min). The aggregation process often discards essential information of traffic state transition (e.g., breakdowns). However, the transition of traffic conditions within an aggregation interval is not well understood. This study explored traffic state transition from uncongested to congested regimes that occurred within a predetermined time interval. From two urban freeway locations in Norfolk, Virginia, traffic data archived at 15-min intervals were obtained. A heuristic method based on a Gaussian mixture model was developed to detect the aggregate traffic data that exhibit the transition of traffic states as well as to partition the data statistically into uncongested and congested traffic states. Results show a substantial difference in travel speed (approximately 20 mph) between the two states. In addition, these results illustrate that aggregating these different traffic conditions can cause substantial traffic data aggregation bias by lowering travel speed and flow rates, especially in high traffic flow situations. Finally, new insights into valid traffic data aggregation and speed–flow–concentration relationship development are discussed.

Revisiting Access and Aggregation Network Architecture

Optical technologies allow the end-user to take advantage of a very high bitrate access. This in turn modifies traffic patterns to be supported by access and aggregation (metro) networks. The present paper first proposes tentative traffic scenarios to assess future capacity requirements for these networks. It is shown that the current aggregation architecture based on primary and secondary aggregation rings should be reconsidered to limit potential bottlenecks and to take account of both infrastructure costs and potential energy savings. The paper then presents alternative architectures to revise and move the boundaries existing today between access and aggregation networks. A first alternative architecture is fully centralized and performs traffic aggregation in a central location. The second alternative architecture proposes to locate the first aggregation points (called Next Generation Points of Presence) on the primary aggregation ring and to centralize control functions.

Hybrid Technique for Enhancing Quality of Service in Wireless Network

This paper x-rays a hybrid technique for enhancing Quality of Service (QoS) technique, a medium access scheme that can provide virtually collision-free environment for an infrastructure high-speed wireless network. While the simple and scalable Differentiated Services (DiffServ) QoS control model is suitable for the core part of the network, a more explicit, admission and reservation based QoS mechanisms are required in the wireless access segment of the network where the resources available and the levels of traffic aggregation render the DiffServ principles less effective, Integrated services (IntServ) provides fine-grained service guarantees to individual flows. The proposed mechanism shall support both IntServ and DiffServ QoS approaches, thereby enhancing the different QoS requirements under different scenarios.

Elastic optical networks: The global evolution to software configurable optical networks

Worldwide operator deployment of high-speed 100G coherent optical networks is currently underway. To ensure a competitive solution offering significant performance improvements to cope with the ever-increasing traffic demand, a novel network concept has been proposed for improved resource utilization based on “elasticity”; specifically, the ability to make a number of previously fixed transmission parameters tunable, for example optical data rate or channel spacing. The benefits are numerous, including increased network capacity, lower cost per bit, and improved energy efficiency and scalability. In this paper, we review the work carried out within the Cooperation for a Sustained European Leadership in Telecommunications (CELTIC) Elastic-Optical NETwork (EO-Net) project towards advancing the state of software-configurable optical networking. We identify the key building blocks for enabling elastic optical networks to provide desired performance improvements over static optical networks. We examine the design of elastic transponders capable of data rate adaptation, interfaces between client packet devices and transponders supporting flexible traffic aggregation, and associated algorithms for traffic grooming and routing. We also perform network cost/energy analyses. Finally, we review the experimental demonstration of such elastic functionalities.

Bandwidth-elastic OFDM-PON based on orthogonal band multiplexing for upstream transmissions

We present a bandwidth-elastic OFDM-PON scheme for upstream transmission with traffic aggregation by orthogonal band multiplexing. The provision of each ONU's frequency band can be set only by software reconfiguration without any hardware changes. Elastic bandwidth adjustment should meet the bandwidth requirement and transmission quality. With non-uniform subcarriers distribution and adaptive modulation, OFDM-PON can achieve a flexible bit rate and spectrum density to realize the elasticity in bandwidth. Non-uniform subcarriers distribution may bring power variation, which will degrade the transmission performance for the ONU with lower received power. This can be mitigated by adaptive power control according to the filling ratio of each ONU. Adaptive modulation format is used to balance the bandwidth requirement and transmission performance. In simulation, aggregated 20Gb/s OFDM signal with both non-uniform subcarriers distribution and adaptive modulation format have been collectively received to verify the bandwidth elastic scheme.

The case for random access in OFDMA femtocells

Data services in current cellular networks are growing exponentially, due to the proliferation of high-end mobile devices (smartphones, tablets, ereaders) supporting ever increasing multimedia applications. Clearly, availing of new spectrum (as with 4G allocations) is a necessary part of meeting this challenge, but so are improved network architectures that achieve enhanced spatial spectral efficiency (bits per second per Hertz per area). 4G network operators are moving toward a heterogeneous architecture consisting of overlaid cells of various sizes. A variety of low-power, small-cell base stations and relays are being deployed to increase capacity around local, typically indoor hotspots. The primary concern in such scenarios is understanding the nature and impact of inter-cell interference in dense deployments of such unmanaged small cells, and arriving at solutions for its mitigation. Resource allocation in traditional wide-area cellular networks usually assume a fully loaded network (i.e. many simultaneous active users in a cell) where the system performance is insensitive to the activity of a single user. This assumption is not suitable for femtocells which are designed to serve very few (indoor) users and thus lacks the presumed traffic aggregation. This article provides a fresh look at the femtocell interference problem from a multiple access perspective. It first compares the multi-channel features inherent to OFDMA with traditional multi-channel MAC designs for wireless LANs and highlights how the ability to schedule users in both time and frequency as afforded by OFDMA, can be exploited to achieve more effective (distributed) random access. A simplified MAC model that hides the complexity of LTE protocol stack is proposed to facilitate the design and analysis of random access MAC algorithms in the context of OFDMA femtocells.

An Energy-Efficient Attack Detection Protocol for WSN

Traffic attack and false data aggregation attack are serious to wireless sensor networks. How to detect the two kinds of attack is a difficult problem. An energy-efficient attack detection protocol is proposed in this paper. The detection protocol uses linear prediction to establish easy ARMA(2,1) model for sensor nodes. In the detection protocol, different nodes play different roles, and use different monitor schemes. Virtual cluster head and monitor nodes are elected. Monitor nodes monitor cluster head, and member nodes are monitored by their cluster head. At the same time, secure data aggregation schemes are added to the protocol. Simulation shows that, the detection protocol can real-time predict traffic attacks, and insure correct data aggregation, but consume less energy.

A Secure and Energy-Efficient Rooting Protocol for WSN

In directed diffusion rooting protocol, interest and exploratory data are disseminated by flooding, which will bring broadcast storm resulting in substantial energy consumption of wireless sensor networks. Grid-based directed diffusion rooting protocol can improve energy efficiency where geographic grids are constructed by self-organization of nodes using location information. Flooding of interest and exploratory data is limited in grid head nodes. But grid-based directed diffusion rooting protocol considers less about security. To adapt to environments with high security requirements, traffic attack detection and secure data aggregation schemes are added to grid-based directed diffusion rooting protocol. Simulation shows that the proposed schemes can real-time predict traffic attacks and improve accuracy of data aggregation results when networks are under attacks. At the same time, the protocol consumes less energy and extends lifetime of networks.

Mean–variance relationship of the number of flows in traffic aggregation and its application to traffic management

We consider the mean–variance relationship of the number of flows in traffic aggregation, where flows are divided into several groups randomly, based on a predefined flow aggregation index, such as source IP address. We first derive a quadratic relationship between the mean and the variance of the number of flows belonging to a randomly chosen traffic aggregation group. Note here that the result is applicable to sampled flows obtained through packet sampling. We then show that our analytically derived mean–variance relationship fits well those in actual packet trace data sets. Next, we present two applications of the mean–variance relationship to traffic management. One is an application to detecting network anomalies through monitoring a time series of traffic. Using the mean–variance relationship, we determine the traffic aggregation level in traffic monitoring so that it meets two predefined requirements on false positive and false negative ratios simultaneously. The other is an application to load balancing among network equipments that require per-flow management. We utilize the mean–variance relationship for estimating the processing capability required in each network equipment.

Detecting Period and Burst Durations in Video Streaming by Means of Active Probing

The growth of broadband Internet access across the world for the last 10 years has made new business models possible. Services which before mainly were provided by network operators and in dedicated networks have now migrated to the open Internet. This has created a global service provider market, using the Internet as platform. The network operators are in many cases left with only providing the broadband access service. For the global service providers, continuous effort is put into the field of finding smart methods for bringing new and advanced services to the market without asking for e.g. QoS features from the involved network operators. This type of service delivery is called Over-The-Top (OTT). The concept of making services able to adapt their network and transport requirements during time of delivery is a strong contribution to success for OTT services.The focus of the work in this thesis, is methods for improving various aspects - as defined by my research questions - related to QoS and potentially also QoE for dynamic adaptive video streaming over HTTP (DASH) services. The motivation for focusing on video services is based on their high QoS requirements (i.e. bandwidth) and also popularity in terms of usage.In the work presented in this thesis, I have studied the behaviour and performance of DASH services by means of simulations, measurements and experiments. Based on insight obtained through this, I established a hypothesis on how QoS and QoE aspects could be improved for users present in the same home network environment. My hypothesis was that making more accurate information available about both services and network conditions in near real-time could facilitate improved control methods. The effectiveness of my suggested methods have in most cases been analysed by means of implementation in an experimental lab scenario, and supported by simulations and analytical approaches when appropriate.The findings presented in the included papers are all closely related and map into the research model used. This model is composed of Knowledge Plane, Monitor Plane and Action plane components located in both service endpoints and involved network components. As my main focus has been on OTT service delivery, the main contributions of my work apply to service endpoints, i.e. components in the home network and on the server side. The server side would in many cases be represented by a Content Delivery Network (CDN) node.The main research questions identified are:RQ1: In a home network how to (autonomously) control the performance of DASH based services.RQ2: How to provide fairness and stability for competing DASH sessions using service endpoint functionality.RQ3: How to choose appropriate quality levels for a DASH session.The main contributions from my research are:C1: A method for controlling the quality levels of DASH in the home gateway.C2: A method for improving fairness among competing DASH sessions.C3: A method for shaping traffic aggregates on access links with DASH components.C4: A method for estimating available bandwidth on access links when DASH sessions are present.

Scalable and energy-efficient packet switches based on multi-granular forwarding operations

Telecommunication networks are evolving due to rapid growth of internet traffic and the necessity to satisfy the new requirements of emerging packet services. Upgrading of network devices so as they can allow scalable and full line rate traffic aggregation and eliminate any internal performance bottlenecks is crucial. In packet switching devices, since data plane functionalities need to be executed for each incoming packet and power per given bandwidth is strongly related to the amount of processing on this data, packet processing at ultra-high rate is becoming the major challenge. The main trend to address such power consumption and scalability issues is to bypass packet switches by switching traffic at lower layers. This results in the packet optical transport network approach, where packet switching provides flexible end-to-end connectivity based on tunnel encapsulation while wavelength switching, exploiting optical bypass, allows reducing electrical switch size at transit nodes. There are also opportunities consisting in simplifying packet switch functionalities or designing completely different packet switch architectures. In this paper a new Ethernet aggregation and switching solution with potentialities to simplify and scale Ethernet switch forwarding functionality is proposed. This solution, based on a burst-basis transmission compliant with the Ethernet Standard, is able to maintain flexibility and any to any connectivity deriving from the connectionless nature of Ethernet. At the same time, it provides Ethernet technology with efficient aggregation capabilities allowing to reduce processing of transit traffic. This is allowed thanks to an Ethernet burst structure conceived as a variable number of consecutive frames of the same connection preceded by a proprietary burst control frame carrying information necessary for burst data frames classification. As a result, burst control frames experience the conventional Ethernet switch packet processing while data frames are mapped on the corresponding queue/output port according to the result of control frames classification. The proposed solution also provides the possibility to recognize data frames of the same burst through a proprietary inter-frame gap inserted among them; that allows to dynamically adapt burst size to the available bandwidth at transit nodes in order to limit frame delay and jitter and to support intermediate grooming. These features make it a very competitive approach in the context of packet optical transport being able to support dynamic multi-granular switching. The proposed solution has been validated by estimating its efficiency in terms of energy consumption with respect to a commercial packet switch. The impact of burst transmission on packet delay and jitter across ring and mesh networks has been also evaluated through different sets of simulations.

Estimating Available Bandwidth on Access Links by Means of Stratified Probing

The growth of broadband Internet access across the world for the last 10 years has made new business models possible. Services which before mainly were provided by network operators and in dedicated networks have now migrated to the open Internet. This has created a global service provider market, using the Internet as platform. The network operators are in many cases left with only providing the broadband access service. For the global service providers, continuous effort is put into the field of finding smart methods for bringing new and advanced services to the market without asking for e.g. QoS features from the involved network operators. This type of service delivery is called Over-The-Top (OTT). The concept of making services able to adapt their network and transport requirements during time of delivery is a strong contribution to success for OTT services.The focus of the work in this thesis, is methods for improving various aspects - as defined by my research questions - related to QoS and potentially also QoE for dynamic adaptive video streaming over HTTP (DASH) services. The motivation for focusing on video services is based on their high QoS requirements (i.e. bandwidth) and also popularity in terms of usage.In the work presented in this thesis, I have studied the behaviour and performance of DASH services by means of simulations, measurements and experiments. Based on insight obtained through this, I established a hypothesis on how QoS and QoE aspects could be improved for users present in the same home network environment. My hypothesis was that making more accurate information available about both services and network conditions in near real-time could facilitate improved control methods. The effectiveness of my suggested methods have in most cases been analysed by means of implementation in an experimental lab scenario, and supported by simulations and analytical approaches when appropriate.The findings presented in the included papers are all closely related and map into the research model used. This model is composed of Knowledge Plane, Monitor Plane and Action plane components located in both service endpoints and involved network components. As my main focus has been on OTT service delivery, the main contributions of my work apply to service endpoints, i.e. components in the home network and on the server side. The server side would in many cases be represented by a Content Delivery Network (CDN) node.The main research questions identified are:RQ1: In a home network how to (autonomously) control the performance of DASH based services.RQ2: How to provide fairness and stability for competing DASH sessions using service endpoint functionality.RQ3: How to choose appropriate quality levels for a DASH session.The main contributions from my research are:C1: A method for controlling the quality levels of DASH in the home gateway.C2: A method for improving fairness among competing DASH sessions.C3: A method for shaping traffic aggregates on access links with DASH components.C4: A method for estimating available bandwidth on access links when DASH sessions are present.

Definition and Performance Evaluation of a Low-Cost/High-Capacity Scalable Integrated OTN/WDM Switch

Digital reconfigurable optical add–drop multiplexer systems are characterized by optical–electrical–optical (OEO) conversion of wavelength division multiplexing line wavelengths and by an electronic switching providing wavelength routing. The recent implementation of monolithically integrated large-scale photonic integrated circuits (PICs) in indium phosphide of terabit capacity cross-point switches and of high-capacity optical transport network (OTN) processor chips has allowed not only a considerable reduction in cost and power consumption of the OEO conversion stage but has also enabled the integration, in the same hardware, of OTN sub-wavelength switching and wavelength switching. To reduce the switching fabric complexity, we propose and investigate the structure of a scalable switch core composed of a space switching fabric routing only signals at a higher rate (high-order optical channel data unit (ODU)) and by OTN time–space switching fabrics switching both signals at a lower rate (low-order ODU) and a higher rate (high-order ODU). The lower hardware complexity of the proposed switching fabric is to be paid with a sub-flow blocking that we have investigated by introducing an analytical model validated by simulation. The blocking performance is evaluated as a function of the main switch and traffic parameters and under some traffic aggregation and routing policies. We show that in some traffic scenarios the blocking probability can reach a value of 10−8 if suitable resource management policies are adopted.

Inefficiency of MaxWeight scheduling in spatial wireless networks

MaxWeight scheduling has gained enormous popularity as a powerful paradigm for achieving queue stability and maximum throughput in a wide variety of scenarios. The maximum-stability guarantees however rely on the fundamental premise that the system consists of a fixed set of flows with stationary ergodic traffic processes. In the present paper we examine networks where the population of active flows varies over time, as flows eventually end while new flows occasionally start. We show that MaxWeight policies may fail to provide maximum stability due to persistent inefficient spatial reuse. The intuitive explanation is that these policies tend to serve flows with large backlogs, even when the resulting spatial reuse is not particularly efficient, and fail to exploit maximum spatial reuse patterns involving flows with smaller backlogs. These results indicate that instability of MaxWeight scheduling can occur due to spatial inefficiency in networks with fixed transmission rates, which is fundamentally different from the inability to fully exploit time-varying rates shown in prior work. We discuss how the potential instability effects can be countered by spatial traffic aggregation, and describe some of the associated challenges and performance trade-offs.

GMPLS-enabled MPLS-TP/PWE3 node with integrated 10 Gbps tunable DWDM transponders: design and experimental evaluation

In this paper we propose a more cost-efficient alternative to current transport network technologies (SONET/SDH) based on the high-bandwidth transport and deterministic performance of the optical circuit technologies (i.e., WSON) along with the efficient aggregation and statistical multiplexing of a packet transport technology (i.e., MPLS-TP) to support IP and Ethernet services. The purpose is to achieve cost reductions, simplified operations and flexible scalability in transport networks. We present the architectural design, implementation and the performance evaluation of the forwarding capabilities of a MPLS-TP/PWE3 node with integrated 10Gbps tunable DWDM transponders, extending the GMPLS-enabled WSON transport network of the ADRENALINE Testbed. The node has been implemented using commercial off-the-shelf hardware and the forwarding engine has been implemented using open source software. An evaluation of the node is provided by means of analyzing the obtained throughput and CPU usage in different evaluation scenarios with different traffic grooming and traffic aggregation strategies.

Collective reception of orthogonal band multiplexed data streams for OFDM-PON upstream transmissions

We propose and demonstrate a novel OFDM-PON upstream transmission architecture with traffic aggregation by orthogonal band multiplexing. The aggregated data streams that propagate in different fiber lengths from ONUs are collectively received and demodulated using one receiver, when the OFDM signals are in a synchronous state. In simulation, four optical network units (ONUs) transmit upstream data at four different frequency bands, and use orthogonal band multiplexing with a proper configuration. The orthogonal band multiplexed 10-Gb/s OFDM signal is collectively received to validate the feasibility of the architecture. We also conduct a proof-of-concept experiment to verify the orthogonal band multiplexing and collective reception. We also verify that the tolerance to the time mismatch of the orthogonal band multiplexing is twice of the CP length.

A comprehensive study of path-level performance evaluation and traffic aggregation for discrete-time tandem network

A simple and systematic path-level performance evaluation method mainly composed of a decomposition technique and a parameter-fitting algorithm is proposed in this paper. With comprehensive considerations, this method works for a discrete-time tandem network with input of two-state Markov-modulated Bernoulli processes (MMBPs), which have potential applications in computer and communication networks. Of course, this proposed method offers convenience of traffic aggregation and decomposition for multiple MMBPs. Furthermore, it can be easily extended to work for tree-type networks. To validate the proposed method, several experiments are conducted to demonstrate that the proposed method has good accuracy in terms of delay, delay variance, and packet loss probability. For further checking the effectiveness of this method, comparisons with some closely related methods in the literature are also made.