QoS routing granularity in MPLS networks

This study investigates how constraint-based routing decision granularity significantly affects the scalability and blocking performance of QoS routing in an MPLS network. Coarse granularity, such as per-destination, has lower storage and computational overheads but is only suitable for best effort traffic. On the other hand, fine granularity, such as per-flow, provides lower blocking probability for bandwidth requests, but requires a huge number of states and high computational cost. To achieve cost-effective scalability, this study proposes using hybrid granularity schemes. The overflowed cache of the per-pair/flow scheme adds a per-pair cache and a per-flow cache as the routing cache, and performs well in blocking probability. The per-pair/class scheme groups the flows into several paths using routing marks, thus allowing packets to be label-forwarded with a bounded cache     

QoS routing for MPLS networks employing mobile agents

The implementation of new networking technologies, such as multiprotocol label switching and differentiated services, will introduce powerful features to the near-future Internet backbone, making a significant contribution to the overall end-to-end provision of quality of service. However, to achieve such an improvement these technologies require not only effective support from current routing algorithms, but also enhanced capabilities, which are currently being developed. To contribute to this development, a novel and powerful scheme is introduced in this article that provides a means of supporting QoS routing through the use of mobile software agents. Specifically, we describe the use of mobile agents to efficiently realize multipoint-to-point routing trees by means of the Wave paradigm, while satisfying the QoS requirements of the set of traffic streams involved in the process. Both benefits and important issues to be considered when using mobile agent schemes in QoS routing are further stressed     

一个MPLS流量工程的QoS路由算法

传统Internet中,多媒体流量和实时电子商务应用会引起品质的降低。这可以通过在网络中动态地建立有带宽和延迟保证的路径来解决。讨论了基本算法,如最宽最短路径（WSP）,复杂一些的算法如最小冲突路由（MIRA）或基于剖面的路由。提出了一个新的MPLS网络中的Diff-Serv流的QoS路由算法。这个方法在维持网络效率的同时,有效地传输多媒体流量。     

A bi-criteria minimum spanning tree routing model for MPLS/overlay networks

The MPLS platform enables the implementation of advanced multipath and multicast routing schemes. This work develops and analyses the performance of a new bi-criteria minimum spanning tree model intended for routing broadcast messages in MPLS networks or constructing tree-based overlay networks. The aim of the model is to obtain spanning trees which are compromise solutions with respect to two important traffic engineering metrics: load balancing cost and average delay bound. An exact solution to the formulated bi-criteria optimization problem is presented, which is based on an algorithm that enables the computation of the set of supported non-dominated spanning trees. An application model and a set of experiments on randomly generated Internet type topologies will also be presented. Finally a network performance analysis of the model considering three network performance metrics will be shown.     

区分服务中一种基于聚集流内部公平性的标记算法

在现今异构刚络Internet,区分服务体系结构通过对不同应用和不同要求的数据流部署不同等级的服务,以提供较大粒度的服务质量(Quality of Service,QoS)保证.不同流之间的公平性问题是区分服务中的研究热点,而标记策略是提高公平性的有效方法.目前许多标记算法只考虑了聚集流之间的公平性,而忽略了聚集流内部流之间的公平性.本文针对同一个聚集流中可能包含不同类型的单个流情况(比如存在自适应TCP流和非适应UDP流、不同速率的多媒体UDP流、采用不同TCP协议的数据流、不同分组大小的数据流),提出了一种基于聚集流内部公平性的标记算法(Fair Aggregate Traffic Marker,FATM).论文构造了不同情况下的模拟场景,并给出了实验的相关参数设置.大量模拟实验结果表明:标记算法FATM在保持聚集流之间的公平性和网络吞吐量的基础上,提高聚集流内部单个流之间的公平性.     

Historical data learning based dynamic LSP routing for overlay IP/MPLS over WDM networks

Overlay IP/MPLS over WDM network is a promising network architecture starting to gain wide deployments recently. A desirable feature of such a network is to achieve efficient routing with limited information exchanges between the IP/MPLS and the WDM layers. This paper studies dynamic label switched path (LSP) routing in the overlay IP/MPLS over WDM networks. To enhance network performance while maintaining its simplicity, we propose to learn from the historical data of lightpath setup costs maintained by the IP-layer integrated service provider (ISP) when making routing decisions. Using a novel historical data learning scheme for logical link cost estimation, we develop a new dynamic LSP routing method named Existing Link First (ELF) algorithm. Simulation results show that the proposed algorithm significantly outperforms the existing ones under different traffic loads, with either limited or unlimited numbers of optical ports. Effects of the number of candidate routes, add/drop ratio and the amount of historical data are also evaluated.     

IP/MPLS over WDM网中的动态选路和波长分配算法

该文研究了IP/MPLS over WDM网中,利用综合路由法为到达的业务流建立标签交换路径(LSP)时,如何选择是在WDM层为它新建一条光路,还是利用现有的逻辑IP链路来满足其要求,提出一种带宽碎片消除的策略,该策略在决定是否利用逻辑IP链路来建立LSP时,总是尽量减少造成带宽碎片,从而可以有效提高全网的资源利用率,仿真结果表明带宽碎片消除策略可以进一步改善综合路由算法的性能。     

Reliability constrained routing in QoS networks

The issue of handling network failures is becoming increasingly important. In this paper, we address the problem of constrained routing by treating reliability as one of the QoS requirements. The problem is to create a feasible path from a given node to the destination such that the bandwidth and reliability requirements of the path are satisfied and the cost of the path is minimized (Reliability Constrained Least Cost Routing Problem). To solve the problem, we propose an approach which employs a novel concept, called partial protection, wherein backup paths are created for a selected set of domains in the network so as to meet the reliability constraints. The Partial Protection Approach (PPA) has two steps: Primary Path Creation and Backup Path Creation if necessary. To implement PPA, we propose three scalable two-pass resource reservation schemes, viz., Conservative, Optimistic, and Hybrid schemes. These schemes differ depending on whether the backup paths are created during the forward pass, reverse pass, or both. We evaluate the performance of the proposed schemes for dynamic multicast groups with different bandwidth and reliability requirements using average call acceptance rate and average tree cost as performance metrics. Our studies show that group dynamics and reliability requirements have significant impact on the performance of the schemes.     

MM-DSR: Multipath QoS routing for multiple multimedia sources over Ad Hoc mobile networks

Nowadays, services over Mobile Ad hoc Networks (MANETs) are becoming more used, and multimedia services such as video-streaming applications are more demanded. Hence, it is necessary to provide end-to-end QoS over MANETs, although it poses a challenging problem due to the ephemeral structure of these networks. MM-DSR (Multipath Multimedia Dynamic Source Routing) is a multipath routing protocol DSR-based merged with a cross-layer algorithm which is able to provide QoS for multiple sources of video over IEEE 802.11b Ad Hoc networks. The weaknesses of the system with plain DSR and IEEE 802.11b have been analysed and work has been done in order to improve the throughput and the final user quality. The performance of video-streaming applications has been improved under high traffic load conditions over mobile Ad Hoc networks.     

在MPLS网络中如何保证VoIP的QoS

在以IP为基础的网络中,IP网络上传送语音(VoIP)成为新一代语音系统的代表,但其业务质量因由IP网络承载而受到限制.多协议标签交换(MPLS)是当前被普遍看好的高速骨干网络技术,通过MPLS,第三层的路由可以得到第二层技术的很好补充,以保证端到端的服务质量(QoS).将MPLS的QoS特性与区分服务(DiffServ)相结合,可实现更优化的网络业务QoS.     

A novel QoS routing protocol for LEO and MEO satellite networks

The rapid advance of communication and satellite technology pushes broadband satellite networks to carry on multimedia traffic. However, the function of onboard routing cannot be provided in existing satellite networks with inter‐satellite links, and quality of service (QoS) of satellite networks cannot be reliably guaranteed because of great difficulties in processing of long distance‐dependent traffic. In this paper, a two‐layered low‐Earth orbit and medium‐Earth orbit satellite network (LMSN) is presented. A novel hierarchical and distributed QoS routing protocol (HDRP) is investigated, and an adaptive bandwidth‐constrained minimum‐delay path algorithm is developed to calculate routing tables efficiently using the QoS metric information composed of delays and bandwidth. The performance of LMSN and HDRP is also evaluated through simulations and theoretical analysis. Copyright © 2007 John Wiley & Sons, Ltd.     

QoS online routing and MPLS multilevel protection: a survey

A survey of MPLS protection methods and their utilization in combination with online routing methods is presented in this article. Usually, fault management methods pre-establish backup paths to recover traffic after a failure. In addition, MPLS allows the creation of different backup types, and hence MPLS is a suitable method to support traffic-engineered networks. In this article, an introduction of several label switch path backup types and their pros and cons are pointed out. The creation of an LSP involves a routing phase, which should include QoS aspects. In a similar way, to achieve a reliable network the LSP backups must also be routed by a QoS routing method. When LSP creation requests arrive one by one (a dynamic network scenario), online routing methods are applied. The relationship between MPLS fault management and QoS online routing methods is unavoidable, in particular during the creation of LSP backups. Both aspects are discussed in this article. Several ideas on how these actual technologies could be applied together are presented and compared.     

QoS aware traffic grooming and integrated routing on IP over WDM networks

In this article, we consider traffic grooming and integrated routing in IP over WDM networks. The challenges of this problem come from jointly considering traffic grooming, IP routing, and lightpath routing and wavelength assignment (RWA). Due to the high bandwidth of optical fiber, there exists a mismatch between the capacity needed by an IP flow and that provided by a single lightpath. Traffic grooming is therefore used to increase the network utilization by aggregating multiple IP flows in a single lightpath. However, traffic grooming incurs additional delays that might violate Quality-of-Service (QoS) requirements of IP users. In this work, the tradeoff between traffic grooming and IP QoS routing is well-formulated as a mixed integer and linear optimization problem, in which the revenue from successfully provisioning IP paths is to be maximized. Problem constraints include IP QoS, routing, optical RWA, and the WDM network capacity. We propose a novel Lagrangean relaxation (LGR) algorithm to perform constraint relaxation and derive a set of subproblems. The Lagrangean multipliers are used in the proposed algorithm to obtain a solution in consideration of grooming advantage and resource constraints simultaneously. Through numerical experiments and comparisons between the proposed algorithm and a two-phase approach, LGR outperforms the two-phase approach under all experimental cases. In particular, the improvement ratio becomes even more significant when the ratio of IP flow to the wavelength capacity is smaller.     

A scalable joint routing and scheduling scheme for large-scale wireless sensor networks

The multihop configuration of a large-scale wireless sensor network enables multiple simultaneous transmissions without interference within the network. Existing time division multiple access (TDMA) scheduling schemes exploit gain based on the assumption that the path is optimally determined by a routing protocol. In contrast, our scheme jointly considers routing and scheduling and introduces several new concepts. We model a large-scale wireless sensor network as a tiered graph relative to its distance from the sink, and introduce the notion of relay graph and relay factor to direct the next-hop candidates toward the sink fairly and efficiently. The sink develops a transmission and reception schedule for the sensor nodes based on the tiered graph search for a set of nodes that can simultaneously transmit and receive. The resulting schedule eventually allows data from each sensor node to be delivered to the sink. We analyze our scheduling algorithm both numerically and by simulation, and we discuss the impact of protocol parameters. Further, we prove that our scheme is scalable to the number of nodes, from the perspectives of mean channel capacity and maximum number of concurrent transmission nodes. Compared with the existing TDMA scheduling schemes, our scheme shows better performance in network throughput, path length, end-to-end delay, and fairness index.     

可在INTERNET网上承载QoS业务的综合服务模型

1 引言 综合服务模型是随着Internet业务及容量不断增加而提出的,它为开发RSVP,RTP协议、处理多媒体/多播业务提供了基本框架,同时也为路由器生产厂商研制开发处理可变负荷的技术提供指南。综合服务模型的前身是D.clark,S.shenker,Lzhang在SIGCOMM92年会上提出的“Supporting Real-time Applicatlons in an Integrated Services Packet Network：Architecture and Mechanisms”。经过几年的发展,综合服务模型已经开始影响路由器及INTERNET的设计,并将在以后的几年中产生更深远的影响。     

An SDN‐based scalable routing and resource management model for service provider networks

Volume of the Internet traffic has increased significantly in recent years. Service providers (SPs) are now striving to make resource management and considering dynamically changing large volume of network traffic. In this context, software defined networking (SDN) has been alluring the attention of SPs, as it provides virtualization, programmability, ease of management, and so on. Yet severe scalability issues are one of the key challenges of the SDN due to its centralized architecture. First of all, SDN controller may become the bottleneck as the number of flows and switches increase. It is because routing and admission control decisions are made per flow basis by the controller. Second, there is a signaling overhead between the controller and switches since the controller makes decisions on behalf of them. In line with the aforementioned explanations, this paper proposes an SDN‐based scalable routing and resource management model (SRRM) for SPs. The proposed model is twofold. SRRM performs routing, admission control, and signaling operations (RASOs) in a scalable manner. Additionally, resource management has also been accomplished to increase link use. To achieve high degree of scalability and resource use, pre‐established paths (PEPs) between each edge node in the domain are provided. The proposed controller performs RASOs based on PEPs. The controller also balances the load of PEPs and adjusts their path capacities dynamically to increase resource use. Experimental results show that SRRM can successfully perform RASOs in a scalable way and also increase link use even under heavy traffic loads.     

A QoS routing strategy using fuzzy logic for NGEO satellite IP networks

Wireless Networks - We present a fuzzy satellite routing strategy (FSRS) for NGEO satellite IP networks to meet multi-class QoS demands. A set of fuzzy rules is established to map the congestion...     

QoS routing in networks with uncertain parameters

We consider the problem of routing connections with quality of service (QoS) requirements across networks when the information available for making routing decisions is inaccurate. Such uncertainty about the actual state of a network component arises naturally in a number of different environments. The goal of the route selection process is then to identify a path that is most likely to satisfy the QoS requirements. For end-to-end delay guarantees, this problem is intractable. However, we show that by decomposing the end-to-end constraint into local delay constraints, efficient and tractable solutions can be established. Moreover, we argue that such decomposition better reflects the interoperability between the routing and reservation phases. We first consider the simpler problem of decomposing the end-to-end constraint into local constraints for a given path. We show that, for general distributions, this problem is also intractable. Nonetheless, by defining a certain class of probability distributions, which includes typical distributions, and restricting ourselves to that class, we are able to establish efficient and exact solutions. We then consider the general problem of combined path optimization and delay decomposition and present efficient solutions. Our findings are applicable also to a broader problem of finding a path that meets QoS requirements at minimal cost, where the cost of each link is some general increasing function of the QoS requirements from the link     

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