多通道并行传输中基于收益最大化的流量分配方法

针对已有的多通道并行传输中的流量分配方法不区分业务、也未考虑资源收益的问题,分析了业务参数模型,引入业务的收益作为多通道并行传输中流量分配的效益评价函数,通过将流量分配映射为带宽分配建立了基于收益最大化的多通道并行传输流量分配模型。基于边际收益递减法则,提出了一种边际收益优先的多业务流多通道并行传输流量分配算法,该算法先根据边际收益优先的贪心策略获取最大化收益的流量分配方案,然后通过调整业务在不同通道间的流量来保证业务的最低质量要求,最后通过典型业务实例分析和仿真实验验证了算法的有效性。与基于带宽比例策略的流量分配算法相比,所提出的方法能够在保证业务质量的前提下,实现带宽资源的优化配置,提高运营商的收益。     

Loss-aware routing algorithm for photonic networks on chip

Photonic network on chip was introduced as an efficient communication platform to overcome the existing challenges in traditional networks on chip. Optical networks provide high bandwidth and low power dissipation infrastructure. Insertion loss is one of the important parameters in photonic networks on chip. In this study, we propose a solution in routing algorithm level in order to reduce insertion loss in photonic network on chip, by passing packets through paths with lower number of optical elements. Simulation results reveal that a novel approach in the routing level decreases insertion loss as much as possible, energy consumption and optical power budget. Our proposed routing has 29.05% less insertion loss under all2all traffic pattern for blocking torus topology, and it has about 12.37% less insertion loss for TorusNX topology in comparison with primary dimension-ordered routing. Proposed routing algorithm increases both the network bandwidth and scalability.     

Multi-path routing versus tree routing for VPN bandwidth provisioning in the hose model

In this paper we study the bandwidth provisioning of VPN service in the hose model with multi-path routing and tree routing. We have investigated the bandwidth efficiency and blocking performance of these two routing schemes. Our study shows that without any restriction on the maximum fraction of traffic on a path (MFTP), multi-path routing often turns out to be single path routing, and only reduces the total bandwidth requirement slightly at rare combination of network topologies and hose parameters. In order to alleviate the overprovisioning problem of the hose model, we propose the concept of sub-provisioning and study the blocking performance using static reduced provisioning. The results show that with full provisioning, the two routing schemes have almost the same blocking performance. However, with sub-provisioning and the variation of the MFTP constraint, multi-path routing is capable of delivering a significant improvement in blocking performance, often better than tree routing by a few orders of magnitude. The improvement is attributed to the multiple alternative paths brought in by the MFTP constraint. With sub-provisioning, the link bandwidth availability becomes the restricting factor in admitting a connection. Having multiple paths, a connection request is able to explore available bandwidth more thoroughly in the network, thus increasing its chances of being admitted. We employ both analytical model and discrete event simulation for the blocking performance study. The analytical model is developed based on the multi-rate reduced load approximation technique and the simulation is carried out using the OPNET simulator. The close agreement between analytical and simulation results indicate the validity of the approach.     

Achieving optimal revenues in dynamically priced network services with QoS guarantees

We have previously proposed the use of dynamically priced network services to provide QoS guarantees within a network. End-to-end QoS can be achieved by concatenating several of these services, perhaps from different ISPs. In this paper we consider the problem of a single ISP determining the bandwidth to allocate to each service, and on which path, in order to maximize revenue while guaranteeing end-to-end QoS. No knowledge of demand functions is assumed. Optimal allocation of bandwidth to services is first considered, where services are assumed to be routed on predetermined paths. We define the Iterative Allocation Adjustment heuristic, based on the concepts of tatonnement, which, through simulation, is shown to achieve over 95% of the optimal revenue for an ISP. We also examine how to value the links in the network to identify rerouting possibilities, or possible routes for new services, in order to improve the revenue of an ISP.     

Virtual network mapping algorithm in the cloud infrastructure

Network virtualization has received considerable attention recently because a Cloud Provider (CP) that is responsible for deploying a substrate network in the cloud infrastructure uses network virtualization to support multiple Virtual Network (VN) requests over the shared substrate network. However, mapping multiple VN requests with constraints on virtual nodes and virtual links into a shared substrate network presents a significant challenge, and is considered an NP-hard problem. In this paper, we propose a heuristic mapping algorithm that handles online VN requests. The node mapping algorithm selects a substrate node for mapping that satisfies both a virtual node's resource requirement and its amount of requested bandwidth. The link mapping algorithm either maps a virtual link to the shortest substrate path that satisfies the requested bandwidth of the virtual link or uses the cut-shortest path approach to map a virtual link to multiple substrate paths that satisfy the requested bandwidth of the virtual link. The path migration algorithm migrates virtual links to different substrate paths to maximize the number of accepted VN requests in a substrate network. Simulation results show that the proposed heuristic mapping algorithm uses resources more efficiently, produces more revenue, and has better performance than existing mapping approaches.     

IP/WDM网络的虚拓扑设计

为解决IP网络与光网络融合过程中虚拓扑设计的问题,提出基于短光路优先建立的IP/WDM网络动态虚拓扑配置方法。该方法通过引入光通道跳距限制,避免长光路对资源的浪费,达到缩短光通道长度和增强光层建路能力的目的。仿真结果表明,利用该机制配置的虚拓扑进行业务梳理,能够在较宽的负载范围内降低网络阻塞率,提高业务梳理效率。     

Bandwidth Management for Supporting Differentiated Service Aware Traffic Engineering

This paper presents a bandwidth management framework for the support of differentiated-service-aware traffic engineering (DS-TE) in multiprotocol label switching (MPLS) networks. Our bandwidth management framework contains both bandwidth allocation and preemption mechanisms in which the link bandwidth is managed in two dimensions: class type (CT) and preemption priority. We put forward a Max-Min bandwidth constraint model in which we propose a novel "use it or lend it" strategy. The new model is able to guarantee a minimum bandwidth for each CT without causing resource fragmentation. Furthermore, we design three new bandwidth preemption algorithms for three bandwidth constraint models, respectively. An extensive simulation study is carried out to evaluate the effectiveness of the bandwidth constraint models and preemption algorithms. When compared with the existing constraint models and preemption rules, the proposed Max-Min constraint model and preemption algorithms improve not only bandwidth efficiency, but also robustness and fairness. They achieve significant performance improvement for the well-behaving traffic classes in terms of bandwidth utilization and bandwidth blocking and preemption probability. We also provide guidelines for selecting different DS-TE bandwidth management mechanisms.     

MPLS感知区分服务的流量工程的研究

分析了MPLS区分服务和流量工程这两种技术;由于在一些应用情景下,需要使流量工程能够感知流量的类型,因此引入了MPLS感知区分服务的流量工程的方案,来建立基于类的流量中继。着重论述了该解决方案的各个方面,包括路径的计算、建立路径的信令、带宽约束模型等。     

一种时延约束下可靠性保证的服务功能链部署方法

针对网络功能虚拟化环境中底层网络物理节点随机失效导致网络服务中断问题,提出了一种兼顾网络服务可靠性和时延约束的服务功能链部署方法以保证网络服务的可靠性。首先提出一种相邻虚拟网络功能备份实例资源共享的备份机制和单路径与多路径混合的路由策略,然后对时延约束下服务功能链可靠性部署问题建立混合整数线性规划模型,并设计了基于K最短路径扩展的服务功能链部署算法。仿真结果表明,与现有方法相比,该方法降低了节点和带宽资源开销,并提高了网络服务请求接受率。     

Assessment of system reliability for a stochastic-flow distribution network with the spoilage property

In supply chain management, satisfying customer demand is the most concerned for the manager. However, the goods may rot or be spoilt during delivery owing to natural disasters, inclement weather, traffic accidents, collisions, and so on, such that the intact goods may not meet market demand. This paper concentrates on a stochastic-flow distribution network (SFDN), in which a node denotes a supplier, a transfer station, or a market, while a route denotes a carrier providing the delivery service for a pair of nodes. The available capacity of the carrier is stochastic because the capacity may be partially reserved by other customers. The addressed problem is to evaluate the system reliability, the probability that the SFDN can satisfy the market demand with the spoilage rate under the budget constraint from multiple suppliers to the customer. An algorithm is developed in terms of minimal paths to evaluate the system reliability along with a numerical example to illustrate the solution procedure. A practical case of fruit distribution is presented accordingly to emphasise the management implication of the system reliability.     

Models for network design,servicing and monitoring of ATM networks based on the virtual path concept

Virtual Path (VP) concept has gained attention in terms of effective deployment of ATM networks for wide-area environment. In this paper, we present models and algorithms for network design and management of ATM networks based on virtual path concept from a network planning perspective. Our approach is based on statistical multiplexing of traffic within a traffic class by using a virtual path for the class and deterministic multiplexing of different virtual paths, and on providing dynamic bandwidth and reconfigurability through virtual path concept depending on traffic load during the course of the day. For some realistic example networks, we observe that considering network dynamism through variation of traffic during the course of a day by doing dynamic bandwidth and virtual path reconfiguration can save between 10 to 14% in network design costs compared to a static network based on maximum busy hour traffic.     

A biased random-key genetic algorithm for wireless backhaul network design

This paper describes a biased random-key genetic algorithm for a real-world wireless backhaul network design problem. This is a novel problem, closely related to variants of the Steiner tree problem and the facility location problem. Given a parameter h, we want to build a forest where each tree has at most h hops from the demand nodes, where traffic originates, to the root nodes where each tree is rooted. Candidate Steiner nodes do not have any demand but represent locations where we can install cellsites to cover the traffic and equipment to backhaul the traffic to the cellular core network. Each Steiner node can cover demand nodes within a given distance, subject to a capacity constraint. The aggregate set of constraints may make it impossible to cover or backhaul all demands. A revenue function computes the revenue associated with the total amount of traffic covered and backhauled to the root nodes. The objective of the problem is to build a forest that maximizes the difference between the total revenue and the cost associated with the installed equipment. Although we will have a forest when we consider only the backhaul links and root nodes, the addition of demand vertices can induce undirected cycles, resulting in a directed acyclic graph. We consider instances of this problem with several additional constraints that are motivated by the requirements of real-world telecommunication networks.     

IEEE 802.16系统中流模型和带宽分配机制研究

分别给出了IEEE 802.16系统中四类服务的流模型,推导出阻塞概率和带宽的关系。基于分析结果,提出了802.16 WMAN的一种带宽分配的机制,并通过仿真将这种阻塞概率上限算法和只能应用于语音流的Erlang B公式作了比较。结果证明,阻塞概率上限算法可以用来近似计算大型网络中的阻塞概率,且在数值计算上比Erlang B公式更具高效性。     

Admission control for media on demand services

Admission control software is used to make accept or deny decisions about incoming service requests to avoid overload. Existing media streaming software includes only limited support for admission control by allowing for predefined static rules. Such rules limit for example the number of requests that are allowed to enter the system during a certain time or define thresholds concerning the utilization level of a single resource such as network bandwidth. In media streaming applications, however, the bottleneck resource (CPU, Disk I/O, network bandwidth, etc.) might change over time depending on the current demand for different types of audio or video files. This paper proposes a model for adaptive admission control in the presence of multiple scarce resources. Opportunity costs for a service request are determined at the moment of an incoming request and compared to the revenue of a request in order to make an accept/deny decision. Opportunity costs are based on resource utilization, service resource requirements, expected future demand for services, and the revenue per accepted service. The model allows rejection of service requests early to reserve capacity required to perform future service requests with higher revenues. We describe a number of experiments to illustrate the benefits of adaptive admission control models over static admission control rules.     

Methodologies for bandwidth allocation,transmission scheduling,and congestion avoidance in broadband ATM networks

The call types supported in high-speed packet networks vary widely in their bandwidth requirements and tolerance to message delay and loss. In this paper, we classify various traffic sources which are likely to be integrated in broadband ATM networks, and suggest schemes for bandwidth allocation and transmission scheduling to meet the quality and performance objectives. We propose ATM cell-multiplexing using a Dynamic Time-Slice (DTS) scheme which guarantees a required bandwidth for each traffic class and/or virtual circuit (VC), and is dynamic in that it allows the different traffic classes or VCs to share the bandwidth with a soft boundary. Any bandwidth momentarily unused by a class or a VC is made available to the other traffic present in the multiplexer. The scheme guarantees a desired bandwidth to connections which require a fixed wide bandwidth. Thus, it facilitates setting up circuit-like connections in a network using the ATM protocol for transport. The DTS scheme is an efficient way of combining constant bit-rate (CBR) services with variable bit-rate (VBR) stastically multiplexed services. We also described methodologies to schedule delivery of delay-tolerant data traffic within the framework of the DTS scheme. Important issues such as buffer allocations, guarantee of service quality, and ease of implementation are also discussed.     

Performance evaluation of product form cellular mobile communications networks

This paper proposes and analyzes a queueing network model of a cellular mobile communications network including the multiway connection. This model is formulated as a queueing network with multiple call classes and state-dependent transition rates. As the performance measure a handover blocking probability is evaluated based on the product form equilibrium distribution and the constraint matrix whose elements consist of the mean arrival and service rates for individual cells. As a numerical example, an eight-cell cellular system is considered and blocking probabilities for a two-way handover between neighbouring cells are calculated for several network loads and constraint matrices. Since results represent the characteristics depending on individual cells or neighbouring cells, it can be emphasized that this model is useful for the control of QoS taking account of the spatial traffic.     

业务质量约束下最大化收益的HFC频点带宽分配方法

HFC频点带宽的分配是广播电视网络业务提供系统的一项关键技术,直接决定了系统的整体收益.描述了HFC频点带宽资源分配面临的问题,提出基于业务收益函数的频点带宽分配方法.在分析广电网络视频点播、时移电视和高速下载三种典型业务特性的基础上,给出了它们的收益函数,提出了一种基于边际效益的贪婪算法以完成资源的分配.该算法在保证业务质量满足最低要求的基础上,按照各类业务的实际需求分配可用的频点带宽,使系统的收益最大.仿真试验验证了该算法的有效性.     

面向SDN数据中心网络最大概率路径流量调度算法

随着数据中心网络规模的迅速增长,网络带宽利用率低下导致的网络拥塞问题日益突出,通过负载均衡提高数据中心网络链路带宽利用率和吞吐量成为了研究热点.如何结合流量特征、链路状态和应用需求进行流量的合理调度,是实现网络链路负载均衡的关键.针对数据中心突发性强、带宽占用率高的大象流调度问题,提出一种面向SDN数据中心网络最大概率路径流量调度算法,算法首先计算出满足待调度流带宽需求所有路径,然后计算流带宽与路径最小链路带宽之间的带宽比,结合所有路径的带宽比为每一条路径计算路径概率,最后利用概率机制选择路径.算法不仅考虑了流带宽需求和链路带宽使用情况,而且全局地考虑了流调度和链路带宽碎片问题.实验结果表明,最大概率路径调度算法能够有效地缓解网络拥塞,提高带宽利用率和吞吐量,减少网络延迟,从而提高数据中心的整体网络性能和服务质量.     

A local search algorithm for finding optimal transit routes configuration with elastic demand

This paper proposes a new local search algorithm for finding the optimal configuration of subroutes from a set of candidate transit routes in a transportation network. It is intended to maximize the transit ridership while holding the budget constraint. In each iteration of the algorithm, route segments that are likely to absorb more transit passengers are added to the configuration and less‐contributing segments are removed, instead. A path‐based model with elastic demand is applied for traffic assignment problem. The algorithm takes advantage of the equilibrium paths information to speed up the calculations for emerging configurations. A numerical experiment on Sioux‐Falls network indicates that the proposed algorithm can achieve high‐quality solutions at different levels of budget. Also, the run‐time and performance of the algorithm are reported over a large problem instance of the Chicago sketch network with 55 artificial candidate routes.     

A new approach to dynamic bandwidth allocation in Quality of Service networks: Performance and bounds

Efficient dynamic resource provisioning algorithms are necessary to the development and automation of Quality of Service (QoS) networks. The main goal of these algorithms is to offer services that satisfy the QoS requirements of individual users while guaranteeing at the same time an efficient utilization of network resources.In this paper we introduce a new service model that provides per-flow bandwidth guarantees, where users subscribe for a guaranteed rate; moreover, the network periodically individuates unused bandwidth and proposes short-term contracts where extra-bandwidth is allocated and guaranteed exclusively to users who can exploit it to transmit at a rate higher than their subscribed rate.To implement this service model we propose a dynamic provisioning architecture for intra-domain Quality of Service networks. We develop a set of dynamic on-line bandwidth allocation algorithms that take explicitly into account traffic statistics and users’ utility functions to increase users’ benefit and network revenue.Further, we propose a mathematical formulation of the extra-bandwidth allocation problem that maximizes network revenue. The solution of this model allows to obtain an upper bound on the performance achievable by any on-line bandwidth allocation algorithm.We demonstrate through simulation in realistic network scenarios that the proposed dynamic allocation algorithms are superior to static provisioning in providing resource allocation both in terms of total accepted load and network revenue, and they approach, in several network scenarios, the ideal performance provided by the mathematical model.