David Dietrich

Network service embedding across multiple providers with nestor

The migration of network functions (NFs) into virtualized network infrastructures brings significant benefits to enterprise networks, while creating opportunities for new cloud service models (i.e., NF-as-a-Service). Network service embedding (NSE) entails serious challenges, stemming from middle-box policies prescribed by network operators and the implications of NFs on network traffic (i.e., bandwidth conservation or traffic amplification) that complicate the estimation of bandwidth demands. The NSE problem is further exacerbated by the location dependencies of certain NFs, which, in conjunction with the limited geographic footprint of NF providers, raise the need for network service mapping across multiple providers. In this paper, we present a holistic approach to multi-provider NSE. We introduce a new service model that simplifies the specification of network service requests and the estimation of bandwidth demands. We further define topology abstractions tailored to NSE that are exposed to a network service composition layer (NSCL), interposed between the clients and the NF providers. Based on this service model and topology abstractions, we propose Nestor, a system that generates efficient network service embeddings via network graph rendering, request partitioning among datacenters (DCs), and request segment mappings onto DC networks.

TeNOR: Steps towards an orchestration platform for multi-PoP NFV deployment

Network Functions Visualization is focused on migrating traditional hardware-based network functions to software-based appliances running on standard high volume severs. There are a variety of challenges facing early adopters of Network Function Virtualizations; key among them are resource and service mapping, to support virtual network function orchestration. Service providers need efficient and effective mapping capabilities to optimally deploy network services. This paper describes TeNOR, a micro-service based network function virtualisation orchestrator capable of effectively addressing resource and network service mapping. The functional architecture and data models of TeNOR are described, as well as two proposed approaches to address the resource mapping problem. Key evaluation results are discussed and an assessment of the mapping approaches is performed in terms of the service acceptance ratio and scalability of the proposed approaches.

Software-defined wireless mesh networks for internet access sharing

Universal access to Internet is crucial, and as such, there have been several initiatives to enable wider access to the Internet. Public Access WiFi Service (PAWS) is one such initiative that takes advantage of the available unused capacity in home broadband connections and allows Less-than-Best Effort (LBE) access to these resources, as exemplified by Lowest Cost Denominator Networking (LCDNet). PAWS has been recently deployed in a deprived community in Nottingham, and, as any crowd-shared network, it faces limited coverage, since there is a single point of Internet access per guest whose availability depends on user sharing policies.To mitigate this problem and extend the coverage, we use a crowd-shared wireless mesh network (WMN), at which the home routers are interconnected as a mesh. Such a WMN provides multiple points of Internet access and can enable resource pooling across all available paths to the Internet backhaul. In order to coordinate traffic redirections through the WMN, we implement and deploy a software-defined WMN (SDWMN) control plane in one of the CONFINE community networks. We further investigate the potential benefits of a crowd-shared WMN for public Internet access by performing a comparative study between a WMN and PAWS. Our experimental results show that a crowd-shared WMN can provide much higher utilization of the shared bandwidth and can accommodate a substantially larger volume of guest traffic.

AutoEmbed: automated multi-provider virtual network embedding

We present AutoEmbed, a fully-automated framework for VN embedding across multiple substrate networks. To automate VN embedding, AutoEmbed deploys functions over three layers: (i) Service Providers, (ii) VN Providers, and (iii) Infrastructure Providers (InPs). AutoEmbed enables VN Providers to partition VN requests among multiple substrate networks based on resource and network topology information that is not treated as confidential by InPs. Subsequently, each VN segment is mapped by the corresponding InP onto its substrate network. AutoEmbed enables the evaluation of various aspects of multi-provider VN embedding, such as the efficiency and scalability of embedding algorithms, the impact of different levels of information disclosure on VN embedding efficiency, and the suitability of VN request specifications.

Multi-Provider Service Chain Embedding With Nestor

Network function (NF) virtualization decouples NFs from the underlying middlebox hardware and promotes their deployment on virtualized network infrastructures. This essentially paves the way for the migration of NFs into clouds (i.e., NF-as-a-Service), achieving a drastic reduction of middlebox investment and operational costs for enterprises. In this context, service chains (expressing middlebox policies in the enterprise network) should be mapped onto datacenter networks, ensuring correctness, resource efficiency, as well as compliance with the provider’s policy. The network service embedding (NSE) problem is further exacerbated by two challenging aspects: 1) traffic scaling caused by certain NFs (e.g., caches and WAN optimizers) and 2) NF location dependencies. Traffic scaling requires resource reservations different from the ones specified in the service chain, whereas NF location dependencies, in conjunction with the limited geographic footprint of NF providers (NFPs), raise the need for NSE across multiple NFPs. In this paper, we present a holistic solution to the multi-provider NSE problem. We decompose NSE into: 1) NF-graph partitioning performed by a centralized coordinator and 2) NF-subgraph mapping onto datacenter networks. We present linear programming formulations to derive near-optimal solutions for both problems. We address the challenging aspect of traffic scaling by introducing a new service model that supports demand transformations. We also define topology abstractions for NF-graph partitioning. Furthermore, we discuss the steps required to embed service chains across multiple NFPs, using our NSE orchestrator (Nestor). We perform an evaluation study of multi-provider NSE with emphasis on NF-graph partitioning optimizations tailored to the client and NFPs. Our evaluation results further uncover significant savings in terms of service cost and resource consumption due to the demand transformations.

Service chain modeling and embedding for NFV-based content delivery

Increasing over-the-top video consumption endangers the sustainability of content delivery over the Internet. Internet Service Providers (ISP) face difficulties in competing on value-added services with content providers and Content Delivery Network (CDN) operators. In this respect, we propose a new model for the collaboration between content delivery stakeholders, so that CDN operators can deploy their software in ISP infrastructures leveraging on Network Function Virtualization (NFV). As the ISP network topology and utilization is deemed confidential, we use a high-level Service Level Agreement (SLA) for the negotiation of both computing resources and connectivity, allowing the ISP to optimize server selection, while providing at the same time sufficient flexibility to the CDN operators for content delivery. Furthermore, we present a linear programming formulation for the VNF Service Chain Embedding and an heuristic to increase problem tractability with a small cost overhead. Finally, we validate the efficiency of the proposed service chain model for virtual CDN management.

Dynamic Deployment and Optimization of Virtual Content Delivery Networks

Today, over-the-top video streaming is gaining a lot of popularity. In this respect, the virtual content delivery network (CDN) is perceived as a key enabler to circumvent the technical challenges faced by content providers to deliver high-quality content over the Internet. Here, the authors investigate how the two main actors of the video delivery chain--the CDN operator and the ISP--can benefit from network and server virtualization to negotiate dynamic service-level agreements that reduce CDN capital expenditures and operating expenses, while generating more revenue for the ISP. First, the authors present a dataset used to simulate dynamic distributed traffic consumption. Second, they discuss the steps required to deploy and operate a virtual CDN deployed on an ISPs network. Furthermore, they present evaluation results of the proposed solution, based on simple models. Lastly, they elaborate on operational parameters that are used to further optimize the solution. This article is part of a special issue on advancing multimedia distribution.

Policy-compliant virtual network embedding

Virtual network embedding algorithms that optimize the mapping of virtual network (VN) topologies onto a substrate network usually do not comply with the policies of substrate providers which may prefer to identify and embed the most profitable subset of a VN request. Such policy-based VN embedding (VNE) is required by distributed VNE architectures, such as PolyVine, or by auction-based VNE environments. In this paper, we introduce a policy dimension to VNE by proposing a new VNE algorithm that aims at maximizing the revenue without violating the providers policy. In contrast to the greedy nature of most VNE techniques, our algorithm allows a provider to trade short-term revenue gains for higher revenue in the long term and cope better with evolving demands. Our simulation results corroborate the efficiency of our VNE algorithm and show the impact of diverse policy adjustments on resource utilization and generated revenue.

T-NOVA: An Open-Source MANO Stack for NFV Infrastructures

One of the primary challenges associated with network functions virtualization (NFV) is the automated management of the service lifecycle. In this paper, we present a full software-based management and orchestration (MANO) stack which operates with OpenStack and OpenDaylight controllers and has the in-built functionality to automate the key phases of the NFV service lifecycle, namely resource discovery and matching, service mapping, service deployment, and monitoring. The MANO stack is being implemented by the EU FP7 project T-NOVA, with the components being released as open-source software. Service mapping and service deployment solutions developed in the scope of T-NOVA are presented in detail. As a proof-of-concept, we evaluate the performance of a virtualized traffic classifier network function, demonstrating the gains of virtualized hardware acceleration.

Near-Optimal Placement of Virtualized EPC Functions with Latency Bounds

The proliferation of mobiles devices, application sprawl, and the ever-increasing data volume generates significant stress on cellular networks and particularly on the cellular core, also known as the Evolved Packet Core (EPC), i.e., the cellular network component residing between the radio access network and the Internet. This is further exacerbated by the deployment of hardware appliances for the implementation of a wide range of network functions (e.g., gateways, mobility management, firewalls, network address translation), hindering any opportunity for elastic provisioning, and eventually leading to high operational costs and a significant degree of load imbalance across the EPC.