Panagiotis Papadimitriou

Network virtualization architecture: proposal and initial prototype

The tussle between reliability and functionality of the Internet is firmly biased on the side of reliability. New enabling technologies fail to achieve traction across the majority of ISPs. We believe that the greatest challenge is not in finding solutions and improvements to the Internets many problems, but in how to actually deploy those solutions and re-balance the tussle between reliability and functionality. Network virtualization provides a promising approach to enable the coexistence of innovation and reliability. We describe a network virtualization architecture as a technology for enabling Internet innovation. This architecture is motivated from both business and technical perspectives and comprises four main players. In order to gain insight about its viability, we also evaluate some of its components based on experimental results from a prototype implementation.

Adaptive virtual network provisioning

In the future, virtual networks will be allocated, maintained and managed much like clouds offering flexibility, extensibility and elasticity with resources acquired for a limited time and even on a lease basis. Adaptive provisioning is required to maintain virtual network topologies, comply with established contracts, expand initial allocations on demand, release resources no longer useful, optimize resource utilization and respond to anomalies, faults and evolving demands. In this paper, we elaborate on adaptive virtual resource provisioning to maintain virtual networks, allocated initially on demand, in response to a virtual network creation request. We propose a distributed fault-tolerant embedding algorithm, which relies on substrate node agents to cope with failures and severe performance degradation. This algorithm coupled with dynamic resource binding is integrated and evaluated within a medium-scale experimental infrastructure.

AutoSlice: automated and scalable slicing for software-defined networks

We present AutoSlice, a virtualization layer that automates the deployment and operation of software-defined network (SDN) slices on top of shared network infrastructures. AutoSlice enables substrate providers to resell their SDN to multiple tenants while minimizing operator intervention. At the same time, tenants are given the means to lease programmable network slices enabling the deployment of arbitrary services based on SDN principles. We outline the control plane architecture of AutoSlice and discuss the most challenging aspects of the forwarding plane design with emphasis on scalability.

A Rate Control Scheme for Adaptive Video Streaming Over the Internet

In this paper, we propose a new streaming protocol, namely dynamic video rate control (DVRC), which enables adaptive video delivery over the Internet. DVRC operates on top of HDP providing a congestion-controlled flow of unreliable datagrams. The proposed rate control scheme is able to interact with new and existing video streaming applications which are capable of adjusting their rate based on congestion feedback. DVRC attempts to optimize the performance of video delivery with concern to friendliness with interfering traffic. Exploring DVRCs potential through extensive simulations, we identify notable gains in terms of bandwidth utilization and smooth video delivery. Furthermore, our results indicate that the protocol allocates a well-balanced amount of network resources maintaining friendliness with coexisting flows.

A platform for high performance and flexible virtual routers on commodity hardware

Multi-core CPUs, along with recent advances in memory and buses, render commodity hardware a strong candidate for software router virtualization. In this context, we present the design of a new platform for virtual routers on modern PC hardware. We further discuss our design choices in order to achieve both high performance and flexibility for packet processing.

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.

Forwarding path architectures for multicore software routers

Multi-core CPUs, along with recent advances in memory and buses, render commodity hardware a strong candidate for building fexible and high-performance software routers. With a forwarding plane physically composed of many packet processing components and operations, resource allocation in multi-core systems is not trivial. Indeed, packets crossing cache hierarchies degrade forwarding performance, since the bottleneck is main memory access. Therefore, forwarding path allocation and input/output processing become challenging, especially when states and data structures have to be shared among multiple cores. In this context, we investigate a set of input/output processing architectures, as well as resource allocation strategies for forwarding paths. For each packet processing operation, we uncover the gains and possible implications by either running different components concurrently or replicating the same components across different cores.

Virtual Public Networks

Universal access to Internet is crucial. Several initiatives have recently emerged to enable wider access to the Internet. Public Access WiFi Service (PAWS) enables free Internet access to all and is based on Lowest Cost Denominator Networking (LCDNet) -- a set of network techniques that enable users to share their home broadband network with the public. LCDNet takes advantage of the available unused capacity in home broadband networks and allows Less-than-Best Effort (LBE) access to these resources. LCDNet can enable third-party stakeholders, such as local governments, to setup, configure and operate home networks for public Internet access in cooperation with Internet Service Providers. Software-defined networking (SDN) creates new opportunities for the remote configuration and management of such networks at large scale. In this paper, we present Virtual Public Networks (VPuN), home networks created, deployed and managed through an evolutionary SDN control abstraction. This offers more flexibility to users and network operators, allowing them to share and control the network, while providing opportunities for new stakeholders to emerge as virtual network operators.

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.