OVPN软管模型的分层路由及时延优化算法研究

提出了分层式路由算法,先依据软管模型的业务需求对上层网络进行优化,然后映射至物理网络,减少了问题的复杂性.为协调总预留带宽及总平均时延这两个优化目标,定义了用户倾向参数,即依据用户实际要求选择优化目标构建优化网络.仿真结果表明在牺牲一定总预留带宽情况下较大提高了总平均时延.     

An optimal dynamic resources partitioning auction model for virtual private networks

In this paper, we consider the problem of optimizing the Internet Service Provider (ISP) profit by providing a periodic Dynamic Partitioning (DP) model for utilizing network resources in the context of Virtual Private Networks (VPN). In literature, Complete Sharing (CS), Complete Partitioning (CP), and Bandwidth Borrowing (BR) techniques have been proposed for resource allocation where the following limitations can be noticed: VPN operators can exaggerate about their required resources, resources might be underutilized, and optimal bandwidth utilization is not guaranteed. To overcome the above limitations, we propose to dynamically partition the resources over different QoS classes through periodic auctions that can reduce the reasoning of exaggeration and maximize the ISP profit. Thus, we formulate our problem based on the Integer Linear Programming (ILP) that allows us to maximize the ISP profit and provides the optimal: (1) set of profitable VPN connections, (2) bandwidth division of each network link among QoS classes, and (3) routing scheme for the accepted demand. Furthermore, the proposed ILP model allows us to study the sensitivity of the ISP profit to a targeted revenue objective.     

On the cost of virtual private networks

A virtual private network (VPN) is a private data network that uses a nonprivate data network to carry traffic between remote sites. An “Intranet VPN” establishes network layer connectivity between remote Intranet sites by creating an IP overlay network over the nonprivate network, using various tunneling mechanisms. There are two approaches for establishing such tunnels: a “CPE-based approach” and a “network-based approach.” In the first approach, tunnels are established only between the CPE devices, whereas in the second approach tunnels are also established between the routers of the core nonprivate network. In this paper we address the problem of determining a CPE-based and a network-based layout of VPN tunnels while taking into account two factors: the cost of the links over which the VPN tunnels are established and the cost of the core routers that serve as end points for the VPN. We define related graph algorithm problems, analyze their complexity, and present heuristics for solving these problems efficiently     

CHEETAH virtual label switching router for dynamic provisioning in IP optical networks

Enabling new IP-based services such as triple and quad-play, as well as eScience applications at predetermined quality of service (QoS) measures, require the provisioning of guaranteed bandwidth pipes at varying granularities (e.g. from few Mbps to several Gbps and above). Dynamic provisioning of bandwidth pipes, whereby a connection is dynamically setup and released upon signalling, is a cost-effective method of enabling such services. Dynamic provisioning is a new paradigm in network control and management (NC&M) that requires the introduction of control plane (i.e. routing and signaling) capabilities within network elements such as routers, layer 2 switches and layer 1 cross-connects.In this paper we share our experience in the design and deployment of a Generalized Multiple Protocol Label Switching (GMPLS) control plane for layer 2 switches in the experimental Circuit-Switched High-Speed End-to-End Transport Architecture (CHEETAH). We call this software engine CHEETAH Virtual Label Switching Router (CVLSR). CVLSR allows non-GMPLS devices (e.g. Ethernet switches, routers and other cross-connects) to participate in the dynamic provisioning of end-to-end bandwidth-guaranteed connections. It extends the dynamic provisioning of connections to the end-users across different administrative domains. We have successfully deployed the CVLSR in CHEETAH optical network across HOPI/DRAGON network. The interoperability of the CVLSR with commercial GMPLS SONET-based cross-connect switches has been demonstrated.     

Exact approach for the optimal design of virtual private network trees assuming a hose workload

Virtual private network (VPN) design according to a tree topology has been the subject of numerous research papers. Two workload models are commonly used to allow VPN clients to specify the communication capacity they need, the hose and the pipe workload models. As opposed to the pipe model, where bandwidth needs between every pair of endpoints must be specified as a matrix, the hose model has the advantage of simple specification where only one ingress and egress bandwidths per hose endpoint are specified. However, the tree bandwidth costs obtained with the hose workload model are higher by a factor of as much as 2.5 compared to those obtained with pipe workloads Duffield et al. (SIGCOMM Comput Commun Rev 29(4):95108, 1999). In this work, we propose a two-step exact approach to design a VPN tree with minimum bandwidth cost. The first step derives a pipe workload from the user specified hose workload using an exact algorithm. The second step formulates the pipe-based VPN tree bandwidth minimization as a 0–1 integer linear program, which is solved using the exact approach proposed in Thabti et al. (1–6, 2012). The bandwidth costs of VPN trees obtained using this two-step approach are lower by a factor varying between 1.31 and 2.23 compared to VPN trees obtained using the original hose workload. Furthermore, we show that tree solutions obtained using the derived pipe workload satisfy the original hose workload.     

Support for resource-assured and dynamic virtual private networks

This paper describes VServ, a prototype architecture for a virtual private network (VPN) service, which builds and manages VPNs on demand. It allows each VPN to have guaranteed resources and customized control, and supports a highly dynamic VPN service where creation and modification operations can take place on fast timescales. These features are contingent on the automated establishment and maintenance of VPNs. A design process is described that attempts to satisfy the goals of both customer and VPN service provider (VSP). A pruned topology graph and tailored search algorithm are derived from the characteristics of the desired VPN. Although the searching procedure is theoretically intractable, it is shown that the complexity can be mitigated by a multitude of factors, VServ is built over the Tempest, a network control framework that partitions network resources into VPNs. An IP implementation of the Tempest is presented. Resource revocation is a mechanism that the VSP can use to react to violations of service level agreements-a protocol is described to enable graceful adaptation in the control plane to resource revocation events     

Scalability implications of virtual private networks

This article gives an overview of the most promising technologies for service providers to offer virtual private network services. The focus is on the analysis of the scalability implications of these virtual private network mechanisms on existing service provider backbone networks. Very often, when deploying VPN services, service providers will be confronted with a trade-off between scalability and security. VPNs that require site-to-site interconnectivity without strong (cryptographic) security can be deployed in a scalable way based on the network-based VPN model, as long as the interaction between the customer and provider routing dynamics are controlled. VPNs that require strong (end-to-end) cryptographic security should be deployed according to the CPE-based VPN model, using the available IPsec protocol suite     

Building identity-based security associations for provider-provisioned virtual private networks

Provider-provisioned virtual private networks are nowadays well-established networking concepts. They are envisaged as an extension of the basic VPN concept to securely network low-capacity nodes in large-scale personal networks, with the help of network providers. This article presents an adaptation of the Internet Key Exchange (IKEv2) protocol to the context of dynamic tunneling in personal networks. It relies on the providers’ infrastructure to build identity-based security associations. Results of a preliminary security analysis are also provided.     

Power-aware virtual optical network provisioning in flexible bandwidth optical networks [Invited]

Considering the virtual network infrastructure as a service, optical network virtualization can facilitate the physical infrastructure sharing among different clients and applications that require optical network resources. Obviously, mapping multiple virtual network infrastructures onto the same physical network infrastructure is one of the greatest challenges related to optical network virtualization in flexible bandwidth optical networks. In order to efficiently address the virtual optical network (VON) provisioning problem, we can first obtain the virtual links’ order and the virtual nodes’ order based on their characteristics, such as the bandwidth requirement on virtual links and computing resources on virtual nodes. We then preconfigure the primary and backup paths for all node-pairs in the physical optical network, and the auxiliary graph is constructed by preconfiguring primary and backup paths. Two VON mapping approaches that include the power-aware virtual-links mapping (PVLM) approach and the power-aware virtual-nodes mapping (PVNM) approach are developed to reduce power consumption for a given set of VONs in flexible bandwidth optical networks with the distributed data centers. Simulation results show that our proposed PVLM approach can greatly reduce power consumption and save spectrum resources compared to the PVNM approach for the single-line rate and the mixed-line rate in flexible bandwidth optical networks with the distributed data centers.     

Secure virtual private networks: the future of data communications

The Internet is an almost ideal means for information retrieval and exchange. It is cost‐effective, easy to use and easily accessible. However, it can also be susceptible to devious practices such as data tempering, eavesdropping and theft. This paper analyses secure virtual private networks (VPNs) and their use in countering the problems of the Internet. Copyright © 1999 John Wiley & Sons, Ltd.     

IP/ MPLS over WDM网中考虑QoS的VPN业务设计

本文研究了在IP／MPLS over WDM网络中支持不同QoS要求的VPN业务的逻辑拓扑设计问题。对于给定的网络物理拓扑和业务需求矩阵，本文提出，基于不同时延要求的VPN业务逻辑拓扑设计可以运用两种方法加以解决。一为基于迭代的线性规划方法，适合于规模较小的网络。另一个为启发式算法，可运用于网络规模较大的环境。对比仿真结果表明，启发式算法不但较好地解决了不同QoS要求的VPN业务的选路和波长分配问题，还较好地降低了链路的最大负载。     

Resource availability–aware adaptive provisioning of virtual data center networks

Optimal provisioning of virtual networks with varying topologies on their physical counterpart is a major challenge in cloud data centers. Embedding the virtual network on the shared physical infrastructure poses a multitude of challenges to the infrastructure provider. This paper proposes a hybrid approach which adapts to the availability and fragmentation level of residual resources for near‐optimal mapping of multiple virtual data center networks on a substrate data center network. The proposed technique uses coordinated static and dynamic embedding phases, adaptively, to maximize the density of embedding which increases the revenue of the cloud service provider. Also, it judiciously modifies the existing mappings for efficient utilization of resources. Empirical results show that the proposed hybrid approach can attain ～10% higher acceptance ratio compared with the existing exact and heuristic techniques in the literature. With the proposed mixed integer programming model for static embedding, the average path length is reduced by 20% compared with the existing techniques.     

International virtual private networks: Background and tariff survey

Carriers have positioned their networks and dedicated databases to help deliver a service which looks and feels like leased lines but is, in reality, delivered over the public switched telephone network (PSTN).     

QoS provisioning for multimedia wireless networks

As we move towards IP-based multimedia wireless networks with voice, video and data convergence, quality of service (QoS) provisioning will become an increasingly challenging task. One implication is that greater emphasis on managing the call admission and overall network resources will be needed. This paper presents a conservative and adaptive quality of service (CAQoS) framework for provisioning the QoS for both real-time and non-real-time traffic in a multimedia wireless network. Unlike most conventional schemes, which gradually scale down the bandwidth of ongoing connections to accommodate new connection/hand-off requests, CAQoS introduces an early scaling-down of bandwidth for new connections based on a designated provisioning model. The performance of a CAQoS system is evaluated through simulations of a realistic wireless environment. Simulation results show that CAQoS meets our design goals and outperforms conventional schemes.     

Object-oriented specification of a bandwidth management system for ATM-based virtual private networks

This paper describes the specification of a bandwidth management system for ATM-based virtual private networks (vpn). Such a system allows a vpn customer to dynamically modify the bandwidth allocated to vpn connections. The analysis process focuses on the service management information model and interfaces required to provide that service to the customer. The specification work is performed according to a second generation object-oriented development method called Fusion. The vpn service and management architectures as well as the different actors involved are also described in detail.     

An approach for provisioning virtual sensors in sensor clouds

In sensor clouds environments, the provisioning process is a crucial task since it is responsible for selecting physical sensors that will be used to create virtual sensors. However, most works consider the allocation of all sensors within the region of interest, causing serious problems such as the wasting of energy consumption. The objective of this paper is to present ACxSIM, an automatic approach to the provisioning of virtual sensors. ACxSIM includes two algorithms: adaptive clustering algorithm based on similarity (ACASIM) and ant colony optimization for sensor selection based on similarity (ACOSIM). ACASIM first clusters the sensor nodes based on the similarity of its measurements (exploiting the temporal and spatial correlations between them), which may create clusters with nodes not physically close to each other. Therefore, in ACASIM, a cluster represents different geographical areas whose nodes have correlated measurements (according to a defined error threshold). Later, ACOSIM, based on ant colony optimization algorithm, creates virtual sensors by selecting only a subset of nodes from each cluster. In this way, the overall energy consumption of sensor nodes is reduced, prolonging the lifetime of the sensor cloud. Results from experiments in Intel Lab dataset show that the ACxSIM reduces energy consumption by 73.97%, providing a solution to be considered in sensor cloud scenarios.     

WDM-PON中基于AWG的新型OVPN研究

在波分复用无源光网络(WDM-PON)中,提出了一种基于阵列波导光栅(AWG)的新型光虚拟专用网(OVPN)。OVPN采用环形结构,在不同光网络单元(ONU)之间使用波长通道直接通信,不仅保证了ONU之间通信的安全性,而且提高了网络生存性。分别从光功率损耗和系统误码率(BER)进行了数值分析,结果表明,本文结构不仅增加了通信的安全性,而且仅使用4个波长就能实现16个ONU的相互联接,从而节省了波长资源,且具有很强的抗串扰能力。     

Resource provisioning for survivable WDM networks under a sliding scheduled traffic model

Resource allocation in WDM networks, under both the static and dynamic traffic models have been widely investigated. However, in recent years there has been a growing number of applications with periodic bandwidth demands. Resources for such applications can be scheduled in advance, leading to a more efficient utilization of available network capacity. The setup and teardown times of the scheduled demands may be fixed, or may be allowed to slide within a larger window. A number of optimal integer linear program (ILP) solutions for the first problem (fixed setup/teardown times) have been presented in the literature. In this paper we present two new ILP formulations for the more general sliding scheduled traffic model, where the setup and teardown times may vary within a specified range. We first consider wavelength convertible networks and then extend our model to networks without wavelength conversion. Our ILP formulations jointly optimize the problem of scheduling the demands (in time) and allocating resources for the scheduled lightpaths. The fixed window model can be treated as a special case of our formulations. Our formulations are able to generate optimal solutions for practical sized networks. For larger networks, we have proposed a fast two-step optimization process. The first step schedules the demands optimally in time, so that the amount of overlap is minimized. The second step uses a connection holding time aware heuristic to perform routing and wavelength assignment for the scheduled demands.