DiffServ Networks Research Articles

Priority switching scheduler

SummaryWe define a novel core network router scheduling architecture called priority switching scheduler (PSS), to carry and isolate time constrained and elastic traffic flows from best‐effort traffic. To date, one possible solution has been to implement a core DiffServ network with standard fair queuing and scheduling mechanisms as proposed in the well‐known “A Differentiated Services Code Point (DSCP) for Capacity‐Admitted Traffic” from RFC5865. This architecture is one of the most selected solutions by internet service provider for access networks (e.g., customer‐premises equipment) and deployed within several performance‐enhancing proxies (PEPs) over satellite communications (SATCOM) architectures. In this study, we argue that the proposed standard implementation does not allow to efficiently quantify the reserved capacity for the AF class. By using a novel credit‐based shaper mechanism called burst limiting shaper (BLS) to manage the AF class, we show that PSS can provide the same isolation for the time constrained EF class while better quantifying the part allocated to the AF class. PSS operates both when the output link capacity is fixed (e.g., wire links and terrestrial networks) or might vary due to system impairments or weather condition (e.g., wireless or satellite links). We demonstrate the capability of PSS through an emulated SATCOM scenario with variable capacity and show the AF output rate is less dependent on the EF traffic, which improves the quantification of the reserved capacity of AF, without impacting EF traffic.

A Design of Packet Scheduling Algorithm to Enhance QoS in High-Speed Downlink Packet Access (HSDPA) Core Network

Voice over Internet Protocol (VOIP) in an efficient manner is a basic requirement of modern era. The real time and non-real traffics demand customized communication provisioning to get guarantee of service. For this we proposed a user fulfillment design for facilitating packets switching in 3G cellular network to insure provisioning of QoS (quality of service) in DiffServ (Differentiated Services) Network. To enhance QoS for real time traffic by reducing delay, packet loss and jitter, we proposed Low latency queuing (LLQ) algorithm. In this paper, we focused on packet scheduling, Diffserv and QoS classes mapping into Universal Mobile telecommunication System (UMTS) classes and buffering. To associate different types of real time multimedia traffic, the QoS provisioning mechanism used different code points of Diffserv. The new idea in LLQ is to map the video and voice traffics against two separate queues and used priority queuing in Low latency queuing for voice traffic. The results got from reproductions shows that proposed calculation meets the QoS prerequisites.

Análisis de la Arquitectura DIFFSERV sobre redes MPLS para la provisión de QoS en aplicaciones en tiempo real (VoIP)

Actualmente, las redes IP necesitan de QoS para aplicaciones en tiempo real, donde el principal problema está en que las redes IP no tienen un mecanismo para proporcionarlo. En este trabajo, se propuso implementar la arquitectura DiffServ sobre redes MPLS, con el objetivo de mejorar las prestaciones a las redes, brindando un trato diferenciado al tráfico en tiempo real. En el análisis se diseñó un ambiente de pruebas con tres escenarios: redes IP, redes MPLS y MPLS DiffServ, realizados en GNS3 con la herramienta Dig-it 2.61 GUI 0.92, para inyectar tráfico de VoIP y datos utilizando etiquetas para su identificación. Cada contexto fue evaluado con los tres indicadores: retardo, jitter y pérdida de paquetes, mediante la herramienta Wireshark. Nuestro estudio determinó una calidad de servicio de VoIP adecuada con la implementación de MPLS y DiffServ.

Evaluación de Parámetros de QoS en una Red VPN-MPLS Diffserv bajo un Entorno Completo de Emulación de Software Libre

El uso de redes de redes privadas virtuales (VPN-MPLS) se ha vuelto muy común dentro de las empresas gracias a sus múltiples ventajas tales como, la comunicación privada a través de una infraestructura de red pública entre sitios geográficamente diversos. Esto lleva a la necesidad de una red eficiente en términos de calidad de servicio (QoS) para garantizar la fiabilidad y la seguridad de la información. Sin embargo, la implementación de una red VPN-MPLS no es fácil ni económica para las pequeñas y medianas empresas; por lo tanto, en la mayoría de los casos, se requiere usar emuladores que tampoco son gratis. La presente investigación analizó una red VPN-MPLS en términos de métricas QoS: delay, jitter y packet loss. Esta evaluación se realizó en un entorno virtual utilizando sólo herramientas de software libre bajo dos escenarios de prueba, con y sin Servicios Diferenciados (DiffServ). Los resultados mostraron que una red VPN-MPLS DiffServ reduce el delay en aproximadamente 96.78% en VoIP, 39.21% en Datos y 66.83% en Streaming; Además, el jitter se redujo en aproximadamente 27,88% en VoIP y 41,09% en datos.

Priority-Aware Packet Pre-marking for DiffServ Architecture Based on H.264/SVC Video Stream Structure

The H264/SVC codec allows for generation of hierarchical video streams. In the stream of this type video data belonging to different layers have different priority depending on their importance to the quality of the video and the decoding process. This creates new demands on the mechanisms of packet marking, and thus new challenges for the policy guaranteeing QoS parameters, such as those defined in the DiffServ architecture. Therefore, mechanisms of the traffic engineering used in the DiffServ network should, as far as possible, take into account internal distribution of priorities inside video streams. This may be achieved by implementing an appropriate method for packet pre-marking. The paper describes the Weighted Priority Pre-marking (WPP) algorithm for priority-aware SVC video streaming over a DiffServ network. Our solution takes into account the relative importance of the Network ion Layer Units. It also does not require any changes in the implementation of the DiffServ marker algorithm. The results presented confirm that video transmission in the DiffServ domain, based on the WPP packet pre-marking, can provide better perceived video quality than the standard (best effort) streaming of multi-layered SVC video. In addition, a comparison with the transmission of the same video content encoded with the H264/AVC codec also points to the superiority of our proposed method.

Sliding mode learning based congestion control for DiffServ networks

In this study, a robust sliding mode learning control scheme is proposed to address the congestion control problem in differentiated services (DiffServ) networks. A validated non-linear network model is based on fluid flow theory corresponding to two important services, namely, the premium traffic and the ordinary traffic. The proposed congestion controller is able to efficiently cope with both the physical network resource constraints and unknown time delays associated with networking systems. Numerical results are presented to illustrate the effectiveness of the proposed control scheme.

A controllable chaotic immune algorithm for risk-aware routing in DiffServ networks

An integrated routing risk model is constructed, which takes into account the effects of unicast routing on DiffServ network risk consisting of the impacts of interrupted services on network users and path availability. With the objective of minimizing integrated routing risk, a novel controllable chaotic immune routing algorithm (CCIRA) is proposed. Due to the inefficiency of traditional path generation methods, a path generation method based on chaotic search and dynamic adjacency matrix is proposed, improving the generation efficiency of available solutions of routing optimization algorithms. An evolutionary strategy which combines dynamic vaccination and free mutation is used in order to ensure the population diversity and the global convergence of CCIRA. Chaotic search is introduced to population initialization, vaccination and free mutation in order to overcome the uncertainty of the optimization process and optimization results in traditional evolutionary algorithms due to the crossover and mutation strategies being based on random numbers. Simulation results prove that CCIRA is highly efficient and practical. Combining the integrated routing risk model and CCIRA, the risk control performance of our risk-aware routing algorithm is also proved to be superior by the comparison with other algorithms.

A New DiffServ Edge Router with Controlled‐UDP

The existing edge routers can not assign the link capacities between User datagram protocol (UDP) subscribers and Transmission control protocol (TCP) subscribers to ensure the multiple priorities traffics with Differentiate-Serve (DiffServ). To solve the problem, a new DiffServ edge router with Controlled-UDP (C-UDP) is proposed. The proposed DiffServ edge router can control the data rates of UDP and TCP subscribers according to their priorities. In the proposed edge router, there are multi-queues buffers controlled by TCP Active queue management (AQM) and UDP AQM algorithms to implement fair and stable link capacities. The proposed TCP AQM and UDP AQM algorithms achieve the network congestion control and DiffServ by operating AQM parameters on the stable conditions proposed by us. The dynamic simulation results demonstrate the proposed edge router for DiffServ network to be valid.

Supporting SIP-based end-to-end Data Distribution Service QoS in WANs

Assuring end-to-end QoS in enterprise distributed real-time and embedded (DRE) systems is hard due to the heterogeneity and transient behavior of communication networks, the lack of integrated mechanisms that schedule communication and computing resources holistically, and the scalability limits of IP multicast in wide-area networks (WANs). This paper makes three contributions to research on overcoming these problems in the context of enterprise DRE systems that use the OMG Data Distribution Service (DDS) quality-of-service (QoS)-enabled publish/subscribe (pub/sub) middleware over WANs. First, it codifies the limitations of conventional DDS implementations deployed over WANs. Second, it describes a middleware component called Proxy DDS that bridges multiple, isolated DDS domains deployed over WANs. Third, it describes the NetQSIP framework that combines multi-layer, standards-based technologies including the OMG-DDS, Session Initiation Protocol (SIP), and IP DiffServ to support end-to-end QoS in a WAN and shield pub/sub applications from tedious and error-prone details of network QoS mechanisms. The results of experiments using Proxy DDS and NetQSIP show how combining DDS with SIP in DiffServ networks significantly improves dynamic resource reservation in WANs and provides effective end-to-end QoS management.

A Traffic Marker to Improve the Fairness among Aggregated Flows in DiffServ Networks

The fair distribution of bandwidth among different flows is an important research issue in the differentiated services architecture. In this paper FATM (a fair aggregate traffic marker) is proposed to provide the fairness among aggregate flows. FATM guarantees the fairness among the aggregate traffic flows by considering CIR of an aggregate traffic, and also considers maintaining estimated arrival rate for each flow within an aggregate at the boundary router.

The Evolution of the Generalized Differentiated Services Architecture and the Changing Role of the Internet Engineering Task Force

Due to the transition from narrowband access to broadband access, heterogeneous requirements for traffic qualities become increasingly important taking into account the necessities for prioritization of data packets and quality of service guarantees. A transition to active network management and subsequently to a more intelligent Internet traffic architecture is required. In meantime, the role of the IETF changed from developing and enforcing a universal connectivity TCP traffic infrastructure to a platform for dealing with the increasing need for variety in the design of different traffic management infrastructures and the continuous search for new technological solutions.Quality of service differentiation standard tracks was already initiated under the heading of Integrated Services/Resource Reservation Protocol (IntServ/RSVP) and Differentiated Services (DiffServ) architectures nearly fifteen years ago. The analysis of this standard setting process during the last fifteen years shows that neither DiffServ architecture nor IntServ/RSVP has reached the final status of Internet standard. Moreover, important developments of network management design for DiffServ networks did not even reach standard track status, but are considered to be on the non-standard track. This includes the Configuration Guidelines for DiffServ Service Classes. Moreover, Procedures for Modifying the RSVP reached the status of Best Current Practice for the Internet community.From the perspective of fostering the evolutionary search for innovative traffic management architectures the increasing role of optional (non-obligatory) non-standard tracks for quality of service differentiated network management should not be considered as a weakness but as a strength of the IETF. As a standard setting agency the IETF cannot take over entrepreneurial decisions regarding the choice of traffic management investment and the required allocation mechanisms for fulfilling the heterogeneous requirements for traffic qualities and implementing incentive compatible pricing mechanisms. In contrast to the technical neutrality of TCP, market driven network neutrality requires an entrepreneurial search for quality of service differentiation avoiding incentives for Internet traffic service providers to discriminate between possible network applications on the basis of network capacity requirements.Therefore, the traditional market split of telecommunications providers into specialized services based on active traffic management for the provision of high quality of service levels (e.g. VoIP, IPTV) and passive (TCP-based) Internet is unlikely to remain stable within the IP-based next generation networks. A forward looking economic model of active traffic management is provided within a generalized DiffServ architecture based on congestion pricing and quality of service differentiation. Within this “umbrella” architecture for traffic management, a flexible framework for different traffic quality differentiation strategies is provided. Since its basic characteristic is that all applications are bearing the opportunity costs of the required traffic capacities the traditional differentiation between managed services and other IP-based Internet services becomes obsolete. In order to guarantee the high quality of VoIP or IPTV, top quality classes can be introduced using the principle of resource reservation with guaranteed end-to-end control. For applications which are less delay sensitive but still require some active traffic management lower traffic quality classes are sufficient, for those applications which are not delay sensitive a “best effort” transmission class may be introduced.In order to provide incentive compatible quality of service differentiation within a generalized DiffServ architecture transmission charges must be monotone increasing with the highest quality class paying the highest transmission charges, and the best effort class may be provided for free.

DiffServ-aware multicasting in a mobile IPv6 network

In this paper we propose an algorithm to establish a DiffServ-Aware Multicast Tree (DAMT) in a mobile IPv6 network. We first use the modified Prim's algorithm to construct the Maximum Available Bandwidth Map (MABM) in a mobile IPv6 network. Then, both the extended multicast routing table stored in each Edge Router (ER) and the Interface QoS Table (IQT) stored in each Core Router (CR) are created and used to construct a DAMT. Finally, the constructed MABM can be rearranged (R-MABM) in order to keep the same QoS as a Mobile Node (MN) had in the home network when the MN has moved to a new ER. The proposed algorithm solves the architectural conflicts for the integration of multicasting support in the Diffserv network as well as the problems of the Neglected Reservation Sub-tree (NRS) and receiver heterogeneity. It also solves a MN's QoS requirement when the MN moves from one network to another. Simulation results indicate that the proposed algorithm offers better performance than existing approaches in average delay, average packet loss rate, average throughput, the number of control overhead, the usage of bandwidth, the amount of saved link bandwidth, and the accumulated time to find a feasible path, especially in the case where the number of new join MN is large and traffic loads are heavy.

Congestion Control of Differentiated Services Networks by Sliding Mode Control

In this paper sliding mode controllers (SMCs)' techniques used and investigated for congestion control problem of differentiated Services (Diff-Serv) networks. Robustness against modelling uncertainties and disturbances are major feature of sliding mode controller. Chattering phenomenon affects sliding mode congestion control; to overcome this problem second order sliding mode control (SOSMC) is proposed as a congestion controller. There are three type of traffic in Diff-Serv networks; i.e. there are three types of queues and based in that, the quality of their services are categorized. Each of these types of traffic has its own congestion control mechanisms. Stability of each controller is proved by Lyapunov stability law. To evaluate the capabilities of our proposed robust control strategy, simulation results are provided for both sliding mode controllers and second order slide mode controllers and their corresponding efficiencies are compared.DOI: http://dx.doi.org/10.5755/j01.eee.19.1.3264

STATELESS AGGREGATE FAIR MARKING SCHEDULER FOR DIFFERENTIATED SERVICE NETWORKS

In diffserv networks, as the traffic flows vary constantly, it is very difficult to maintain the per-flow state. The computation of rate information of the traffic flow also becomes complex. In this study, we propose a Stateless Aggregate Fair Marking (SAMQ) with Multiple Queue Priority Scheduler for Differentiated Service (DiffServ) networks. Initially, priority scheduler is applied to the flows entering the ingress edge router. If it is real time flow like Voice over IP (VoIP) or Video, then the packets are given higher priority else lower priority. In core router, for higher priority flows the Multiple Queue Fair Queuing (MQFQ) is applied that allows a flow to utilize multiple queues to transmit the packets. In case of lower priority, Stateless Aggregate Fair Marking technique is utilized. This technique applies Core Stateless Fair Queuing (CSFQ) technique for maintaining the rate information of packet flow and distributes the token to each incoming packet without maintaining the per-flow state. By simulation results, we show that this technique improves the throughput of non-real time flows.

Markov Chains Based Dynamic Bandwidth Allocation in DiffServ Network

This letter proposes a Markov chain based model for dynamic bandwidth allocation in DiffServ networks. At a time-slot, the proposed Markov chain is used to predict the bandwidth requirement at the next time-slot, and resource is then allocated accordingly. Such a pre-allocation scheme can effectively reduce the operation overhead in bandwidth allocation and further reduce the connection blocking probability. We present numerical results showing that our dynamic bandwidth allocation mechanism can reduce the network blocking probability by one order of magnitude, compared with the existing bandwidth borrowing mechanism.

An aggregate marker for bandwidth fairness in DiffServ

Surveys and studies on DiffServ exhibit existence of unfairness between aggregates in the excess bandwidth region. Many researchers have proved that providing a proportional fair share of the bandwidth between aggregates solve this. Based on this, aggregate markers such as ItswTCM and I2tswTCM are found to improve bandwidth fairness in DiffServ network among aggregates, when the aggregates are responsive in nature. However, co-existence of non-responsive aggregates with responsive aggregates leads to unfairness. Hence, in this paper an attempt has been made to evade the above unfairness by a new TSW based marker; where the drop precedence of the packet is arrived at an adaptive manner based on its estimated rate and the availability of the network resource. The unique feature of this proposed algorithm is that it provides enhanced fairness not only among responsive aggregates but also between responsive and non-responsive aggregates. Further, simulations have been carried out in NS-2 with changes in RTT, target rate of the aggregates and the number of flows in the aggregate. The results show that the proposed marker reduces the influence of these factors on the fairness performance exhibiting the suitability of the marker for different network topologies.

A new method to implement afij at core routers in diffserv networks.

A new method to implement afij at core routers in diffserv networks.

Precongestion notification: new QoS support for differentiated services IP networks

Admission control is a well-known technique to explicitly admit or block new flows in order to keep a network's traffic load at a moderate level and to guarantee QoS for admitted flows. Flow termination is a new flow control function that terminates some admitted flows when the network capacity does not suffice, such as in the case of unexpected failures. Admission control and flow termination are useful to protect QoS for inelastic flows that require a minimum bit rate. Examples are real-time applications like voice and video. Precongestion notification (PCN) provides feedback about load conditions on the path to boundary nodes. They use this information to implement lightweight admission control and flow termination without per-flow state on interior nodes of a domain. These mechanisms are significantly simpler than explicit reservation schemes. In the context of DiffServ, IP, MPLS, and Ethernet networks, we explain the concept of PCN-based admission control and flow termination, present recent standards of the IETF, and discuss benefits and limitations.

M2I2tswTCM: A new efficient optimization marker algorithm to improve fairness bandwidth in DiffServ networks

The Quality of Service (QoS) requirement Differentiated Services (DiffServ) typically having three main categories of performance metrics—bandwidth, latency and jitter. Although the DiffServ routers provide Per Hop Behaviours (PHBs) to aggregate traffic for different levels of service through the Assured Forwarding (AF) by provides service differentiation to aggregates, an unfairness problem still occurs in DiffServ networks. In order to improve bandwidth fairness along with efficient optimization to alleviate this problem, this article proposes a Double Modified Double Improved time sliding window Three Colour Marker (M2I2tswTCM) algorithm , which makes a new value of γ that depends on the logarithm peak information rate (PIR) and which is added to the adaptive factor that exists in the previous algorithm. Through extensive simulation implementation using the NS-2 under DiffServ network, we compare the fairness of the proposed algorithm with previous algorithms. The results show that the M2I2tswTCM algorithm performed better than the seven marker algorithms in terms of fair bandwidth distribution for different network provision levels.

A Modified Packet Marking Algorithm to Improve Bandwidth Fairness in Diffserv Networks

A Modified Packet Marking Algorithm to Improve Bandwidth Fairness in Diffserv Networks