Interdomain quality of service routing: setting the grounds for the way ahead

A common criticism of the current Internet is the fact that it does not offer quality of service (QoS) guarantees across autonomous system boundaries. The Border Gateway Protocol (BGP) is central to solve this problem, since it enables AS to distribute reachability information. However, BGP is agnostic of any performance or QoS metrics. For this reason, the debate about the requirements for the future interdomain routing architecture and about whether these requirements are best met by an approach of introducing changes into BGP or by replacing BGP is still open. This article provides an insight into the interdomain QoS routing problem. First, the main drawbacks of current interdomain routing with regard to the provision of QoS are identified. Second, a survey of the most relevant interdomain QoS routing approaches are described and discussed. We also give a broad perspective on challenges surrounding the issue of whether to extend or replace BGP to support QoS, with particular emphasis on the technical challenges. However, we also point out some nontechnical unsolved challenges that, in our perspective, are still almost certainly the biggest barrier to the development of interdomain QoS routing.     

A Survey of Routing Protocols that Support QoS in Mobile Ad Hoc Networks

The explosive growth in the use of mobile devices coupled with users' desires for real-time applications has provided new challenges in the design of protocols for mobile ad hoc networks. Chief among these challenges to enabling real-time applications for mobile ad hoc networks is incorporating support for quality of service (QoS), such as meeting bandwidth or delay constraints. In particular, it is important that routing protocols incorporate QoS metrics in route finding and maintenance to support end-to-end QoS. This article extensively and exclusively studies the issues involved with QoS-aware routing and presents an overview and comparison of existing QoS-aware routing protocols. In addition, the open issues that must be addressed to fully support QoS-aware routing are discussed.     

QM2RP: A QoS-Based Mobile Multicast Routing Protocol Using Multi-Objective Genetic Algorithm

With the increasing demand for real-time services in next generation wireless networks, quality-of-service (QoS) based routing offers significant challenges. Multimedia applications, such as video conferencing or real-time streaming of stock quotes, require strict QoS guarantee on bandwidth and delay parameters while communicating among multiple hosts. These applications give rise to the need for efficient multicast routing protocols, which will be able to determine multicast routes that satisfy different QoS constraints simultaneously. However, designing such protocols for optimizing multiple objectives, is computationally intractable. Precisely, discovering optimal multicast routes is an NP-hard problem when the network state information is inaccurate – a common scenario in wireless networks. Based on the multi-objective genetic algorithm (MOGA), in this paper we propose a QoS-based mobile multicast routing protocol (QM²RP) that determines near-optimal routes on demand. Our protocol attempts to optimize multiple QoS parameters, namely end-to-end delay, bandwidth requirements, and residual bandwidth utilization. Furthermore, it is fast and efficient in tackling dynamic multicast group membership information arising due to user mobility in wireless cellular networks. Simulation results demonstrate that the proposed protocol is capable of discovering a set of QoS-based, near-optimal multicast routes within a few iterations, even with imprecise network information. Among these routes one can choose the best possible one depending on the specified QoS requirements. The protocol is also scalable and yields lower multicast call-blocking rates for dynamic multicast group size in large networks.     

A Novel Routing Protocol for Supporting QoS for Ad Hoc Mobile Wireless Networks

The main purposes of this article are to lessen the influence of the fastchanging network topology, rapidly varying bandwidth information, and the increasing size of routing tables onquality of service routing. Based on DSDV (Destination-Sequenced Distance-Vector) routing protocol formaintaining up-to-date routing information, the related research has to update routing tables when networktopology changes; moreover, the routing tables must be updated periodically even though the networktopology has not changed. To put emphasis on QoS routing, they also have to exchange routing tables by thetime of bandwidth information changes. Furthermore, the size of routing tables increases with the numberof mobile nodes; therefore, the precious wireless bandwidth is wasted on transmitting the large-scalerouting tables. In this article, we propose an on-demand-based QoS routing protocol to mitigate theseproblems and to achieve the QoS requirement. The goal of this article is to discover an optimal routewith minimum time delay for transmitting real-time data from a source node hop by hop to adestination node under some predefined constraints. Our contributions are as follows: our researchprovides a rigorous bandwidth definition and bandwidth application, a broad view of bandwidth calculationand reservation, minimizing the size of control packets and the number of control packet transmissions,and an efficient QoS routing protocol.     

对新型网络路由机制的思考

路由是网络的结构基石,新型网络路由机制是构建新型网络体系的必需。目前网际层的路由本质上是所谓的"单下一跳路由"机制,解决网络传输拥塞问题的一个根本措施在于改变当前网络单下一跳的选路模式,允许多条路径的并行传输。边界网关协议(BGP)是目前Internet唯一采用的域间路由协议,针对当前域间路由系统面临的规模可扩展性问题,文章提出了一个规模可扩展的新型分层域间路由架构(s-idra)。除了可扩展性以外,路由体系还面临其他挑战,比如安全性、服务质量(QoS)、组播、移动、动态网络拓扑等等。路由协议尤其是未来新型信息网络体系结构的路由协议的研究任重而道远。     

An adaptive inter-domain PCE framework to improve resource utilization and reduce inter-domain signaling

Upcoming broadband commercial and scientific applications are now demanding high bandwidth pipes across multiple domains with guaranteed Quality of Service (QoS). Recent research initiatives such as the Path Computation Element (PCE) framework are focusing on the development of scalable multi-domain QoS provisioning frameworks, especially within the emerging carrier grade transport technologies based on layer-2 tunnels. QoS provisioning across multiple domains requires that QoS parameters for available transit paths inside a domain be advertised in the inter-domain routing algorithms, while the dynamic inter- and intra-domain connections vary the available resource, and hence require frequent inter-domain updates. The signaling load on the other hand hampers the scalability of the inter-domain routing mechanisms. We propose the use of an adaptive partitioning framework, which can effectively use network resources and at the same time stabilize the advertised domain topologies and thus path advertisements. Our method partitions network resources by pre-reserving resources for inter-domain transit traffic, and uses policies to modify the resource partitioning in order to maintain the available transit capacity between specified bounds. We show by simulations that the proposed mechanism can reduce inter-domain signaling load by 10%-20% and reduce overall blocking inside a domain by creating a trade-off between available resources for intra-domain connections and inter-domain transit connections. The reduction in inter-domain signaling and blocking can be used as a building block to design scalable QoS routing systems for carrier grade transport networks.     

A survey of adaptive bandwidth control algorithms

In packet-switched network traffic management and control, efficiently allocating bandwidth to provide quantitative packet-level QoS to aggregate traffic has been difficult due to unpredictable, unknown statistical characteristics of the aggregate traffic. With inaccurate traffic information, using static bandwidth allocation results in the network being underutilized, or the QoS requirement not being satisfied. An alternative is to use Adaptive Bandwidth Control (ABC), whereby the allocated bandwidth is regularly adjusted over the packet-level time scale to attain a given QoS requirement. This paper provides a literature review of ABC algorithms that guarantee aggregate traffic packet-level QoS metrics, such as the average queue length, packet loss, and packet delay. We describe different ABC algorithms, identify their advantages and shortcomings, and provide some comparative performance evaluation results. Open issues in ABC for future research directions are also discussed.     

基于多项服务质量的域间路由方案

针对广域网中节点数量多,范围广的特点,提出了一种将节点划分成域,并以带宽、时延作为服务质量（ＱｏＳ）指标在域间寻找可行路径的路由方案。该方案由两个算法组成,它们在把真实网络映射成为具有分级结构图的同时给出了满足服务质量要求的可行路径。     

Distributed quality-of-service routing in ad hoc networks

In an ad hoc network, all communication is done over wireless media, typically by radio through the air, without the help of wired base stations. Since direct communication is allowed only between adjacent nodes, distant nodes communicate over multiple hops. The quality-of-service (QoS) routing in an ad hoc network is difficult because the network topology may change constantly, and the available state information for routing is inherently imprecise. In this paper, we propose a distributed QoS routing scheme that selects a network path with sufficient resources to satisfy a certain delay (or bandwidth) requirement in a dynamic multihop mobile environment. The proposed algorithms work with imprecise state information. Multiple paths are searched in parallel to find the most qualified one. Fault-tolerance techniques are brought in for the maintenance of the routing paths when the nodes move, join, or leave the network. Our algorithms consider not only the QoS requirement, but also the cost optimality of the routing path to improve the overall network performance. Extensive simulations show that high call admission ratio and low-cost paths are achieved with modest routing overhead. The algorithms can tolerate a high degree of information imprecision     

QoS routing in ad hoc wireless networks

The emergence of nomadic applications have generated much interest in wireless network infrastructures that support real-time communications. We propose a bandwidth routing protocol for quality-of-service (QoS) support in a multihop mobile network. The QoS routing feature is important for a mobile network to interconnect wired networks with QoS support (e.g., ATM, Internet, etc.). The QoS routing protocol can also work in a stand-alone multihop mobile network for real-time applications. This QoS routing protocol contains end-to-end bandwidth calculation and bandwidth allocation. Under such a routing protocol, the source (or the ATM gateway) is informed of the bandwidth and QoS available to any destination in the mobile network. This knowledge enables the establishment of QoS connections within the mobile network and the efficient support of real-time applications. In addition, it enables more efficient call admission control. In the case of ATM interconnection, the bandwidth information can be used to carry out intelligent handoff between ATM gateways and/or to extend the ATM virtual circuit (VC) service to the mobile network with possible renegotiation of QoS parameters at the gateway. We examine the system performance in various QoS traffic flows and mobility environments via simulation. Simulation results suggest distinct performance advantages of our protocol that calculates the bandwidth information. It is particularly useful in call admission control. Furthermore, “standby” routing enhances the performance in the mobile environment. Simulation experiments show this improvement     

A resource‐tuned QoS multicast routing protocol

This paper presents a novel framework for quality‐of‐service (QoS) multicast routing with resource allocation that represents QoS parameters, jitter delay, and reliability, as functions of adjustable network resources, bandwidth, and buffer, rather than static metrics. The particular functional form of QoS parameters depends on rate‐based service disciplines used in the routers. This allows intelligent tuning of QoS parameters as functions of allocated resources during the multicast tree search process, rather than decoupling the tree search from resource allocation. The proposed framework minimizes the network resource utilization while keeping jitter delay, reliability, and bandwidth bounded. This definition makes the proposed QoS multicast routing with resource allocation problem more general than the classical minimum Steiner tree problem. As an application of our general framework, we formulate the QoS multicast routing with resource allocation problem for a network consisting of generalized processor sharing nodes as a mixed‐integer quadratic program and find the optimal multicast tree with allocated resources to satisfy the QoS constraints. We then present a polynomial‐time greedy heuristic for the QoS multicast routing with resource allocation problem and compare its performance with the optimal solution of the mixed‐integer quadratic program. The simulation results reveal that the proposed heuristic finds near‐optimal QoS multicast trees along with important insights into the interdependency of QoS parameters and resources.     

QoS routing in networks with inaccurate information: theory andalgorithms

This paper investigates the problem of routing flows with quality-of-service (QoS) requirements through one or more networks, when the information available for making such routing decisions is inaccurate. Inaccuracy in the information used in computing QoS routes, e.g., network state such as link and node metrics, arises naturally in a number of different environments that are reviewed in the paper. The goal is to determine the impact of such inaccuracy on the ability of the path-selection process to successfully identify paths with adequate available resources. In particular, we focus on devising algorithms capable of selecting path(s) that are most likely to successfully accommodate the desired QoS, in the presence of uncertain network state information for the purpose of the analysis, we assume that this uncertainty is expressed through probabilistic models, and we briefly discuss sample cases that can give rise to such models. We establish that the impact of uncertainty is minimal for flows with only bandwidth requirements, but that it makes path selection intractable when end-to-end delay requirements are considered. For this latter case, we provide efficient solutions for special cases of interest and develop useful heuristics     

具不确定信息的延迟受限QoS路由研究

QoS路由的目的是找到一条或多条具有足够资源,以满足某种约束条件(如延迟,带宽等)的路径。在实际情况中,关于链路状态的信息并不总是确定的,这种不确定性对QoS路由的选择有着不可避免的影响。探讨其原因,在约束条件为延迟保证的前提下,讨论处理不确定信息的QoS单播路由算法。     

一种非精确状态下满足多QoS约束的 动态组播路由算法

提出了一种非精确状态下满足多QoS约束的动态组播路由算法——DMIQ,该算法采用改进的BF算法作为路径搜索算法,WFQ作为分组调度机制,链路延迟不确定且服从均匀分布,能在非精确状态且满足带宽、延迟抖动和丢包率约束的前提下确定具有最小跳数和开销的动态组播路由.仿真实验表明,DMIQ能在非精确状态且满足多QoS约束的前提下建立动态组播路由,在路由请求平均成功率、平均延迟和平均跳数等衡量指标下表现出良好的性能.     

Intelligent Information‐Centric Networking routing scheme under imprecise information

Information‐Centric Networking (ICN) has been accepted to overcome some weaknesses of the current Internet architecture, showing that “what is being exchanged” is more important than “who are exchanging information.” Given the inadequate considerations on Quality of Service (QoS) and energy saving in ICN routing, we propose in this paper a routing algorithm to enhance the two aspects. At first, on one hand, Cauchy distribution is used as a fuzzy model to evaluate users' QoS requirements, such as bandwidth, delay, and error rate; on the other hand, we formulate energy saving problem to evaluate the green quality of routing algorithm. Then, we design a link selection approach by considering QoS and energy saving, which belongs to a multi‐objective decision problem resolved by intelligent drops algorithm. Finally, we implement the proposed algorithm and compare it with the famous adaptive forwarding mechanism in terms of some significant metrics, and the experimental results reveal that the proposed algorithm is more efficient.     

A QoS Routing Protocol with Bandwidth Allocation in Multichannel Ad Hoc Networks

Mobile multimedia applications have recently generated much interest in mobile ad hoc networks (MANETs) supporting quality-of-service (QoS) communications. Multiple non-interfering channels are available in 802.11 and 802.15 based wireless networks. Capacity of such channels can be combined to achieve higher QoS performance than for single channel networks. The capacity of MANETs can be substantially increased by equipping each network node with multiple interfaces that can operate on multiple non-overlapping channels. However, new scheduling, channel assignment, and routing protocols are required to utilize the increased bandwidth in multichannel MANETs. In this paper, we propose an on-demand routing protocol M-QoS-AODV in multichannel MANETs that incorporates a distributed channel assignment scheme and routing discovery process to support multimedia communication and to satisfy QoS bandwidth requirement. The proposed channel assignment scheme can efficiently express the channel usage and interference information within a certain range, which reduces interference and enhances channel reuse rate. This cross-layer design approach can significantly improve the performance of multichannel MANETs over existing routing algorithms. Simulation results show that the proposed M-QoS-AODV protocol can effectively increase throughput and reduce delay, as compared to AODV and M-AODV-R protocols.     

QoS multicast routing by using multiple paths/trees in wireless ad hoc networks

In this paper, we investigate the issues of QoS multicast routing in wireless ad hoc networks. Due to limited bandwidth of a wireless node, a QoS multicast call could often be blocked if there does not exist a single multicast tree that has the requested bandwidth, even though there is enough bandwidth in the system to support the call. In this paper, we propose a new multicast routing scheme by using multiple paths or multiple trees to meet the bandwidth requirement of a call. Three multicast routing strategies are studied, SPT (shortest path tree) based multiple-paths (SPTM), least cost tree based multiple-paths (LCTM) and multiple least cost trees (MLCT). The final routing tree(s) can meet the user’s QoS requirements such that the delay from the source to any destination node shall not exceed the required bound and the aggregate bandwidth of the paths or trees shall meet the bandwidth requirement of the call. Extensive simulations have been conducted to evaluate the performance of our three multicast routing strategies. The simulation results show that the new scheme improves the call success ratio and makes a better use of network resources.     

QoS-aware multicast routing for the Internet: the design andevaluation of QoSMIC

One of the main problems of the current Internet infrastructure is its inability to provide services at consistent quality-of-service (QoS) levels. At the same time, many emerging Internet applications, such as teleeducation, and teleconferencing, require multicast protocols that will provide the necessary QoS. In this paper, we propose QoSMIC, a multicast routing protocol for the Internet, that provides QoS-sensitive paths in a scalable, resource-efficient, and flexible way. QoSMIC differs from the previous protocols in that it identifies multiple paths and selects the one that can provide the required QoS. Two other key advantages of QoSMIC are its flexibility and adaptivity. First, the distribution tree does not have to be rooted at a preselected core router. Second, we can tradeoff between efficiency metrics depending on our needs; for example, we can tradeoff routing efficiency for a reduction in the control messages. Extensive simulations show that our protocol improves the resources utilization and the end-to-end performance compared to the current protocols. Specifically, our protocol reduces the call blocking probability by a factor of six and reduces the end-to-end delay by as much as 90% compared to the PIM protocol     

基于克隆选择的QoS组播路由优化

衡量QoS组播路由主要性能指标有延时,代价,带宽等,本文所提出的基于遗传算法的多约束QoS组播路由优化算法.引入了一个综合性能指标Q适应度函数,对延时、带宽、代价这3个性能指标进行权衡.以减小组播树的代价和延时,增大带宽,提高组播的服务质量.并对解决传统算法对于存在两组及以上的组播树,他们的代价都是最优的,延时和带宽都满足受限条件时无法选择的问题十分有效的.     

一种应急通信中业务感知的宽带自组网路由协议

随着科技进步,我国在应急通信系统建设上也正高速发展,当前应急通信网络对多媒体业务有着迫切需求,对网络带宽要求更高。而当网络存在多种不同业务时,传统通用的路由协议不再适用,它们大多以最小跳数为路由度量或者是某个单一度量,未能考虑不同业务的服务质量(Quality of Service, QoS)需求,因而无法同时兼顾不同业务流的传输要求。提出了一种应急通信中业务感知的宽带自组网路由策略,对不同类型业务在路由和转发优先级上进行区分。经多次仿真验证,该策略能使网络在满足应急语音业务QoS需求的同时,也能兼顾承载的视频、数据等其他业务的性能。