Panagiotis Georgopoulos

Towards network-wide QoE fairness using openflow-assisted adaptive video streaming

Video streaming is an increasingly popular way to consume media content. Adaptive video streaming is an emerging delivery technology which aims to increase user QoE and maximise connection utilisation. Many implementations naively estimate bandwidth from a one-sided client perspective, without taking into account other devices in the network. This behaviour results in unfairness and could potentially lower QoE for all clients. We propose an OpenFlow-assisted QoE Fairness Framework that aims to fairly maximise the QoE of multiple competing clients in a shared network environment. By leveraging a Software Defined Networking technology, such as OpenFlow, we provide a control plane that orchestrates this functionality. The evaluation of our approach in a home networking scenario introduces user-level fairness and network stability, and illustrates the optimisation of QoE across multiple devices in a network.

Quality evaluation in peer-to-peer IPTV services

Modern IPTV services are comprised of multiple comprehensive service elements in the entire content delivery chain to maximise the efficiency in networking. Audio-visual content may experience various types of impairments during content ingest, processing, distribution and reception. While some impairments do not cause noticeable distortions to the delivered content, many others such as the network transmission loss can be highly detrimental to the user experience in content consumption. In order to optimise service quality and to provide a benchmarking platform to evaluate the designs for future audio-visual content distribution system, a quality evaluation framework is essential. We introduce such an evaluation framework to assess video service with respect of user perception, while supporting service diagnosis to identify root-causes of any detected quality degradation. Compared with existing QoE frameworks, our solution offers an advanced but practical design for the real-time analysis of IPTV services in multiple service layers.

HomeVisor: Adapting Home Network Environments

This paper considers SDN, and OpenFlow in particular, as technology to develop the next generation of more flexible, configurable and automated home networks. We identify the problems with the current state of the art in home networking, which includes a lack of user engagement in home network maintenance and configuration, Internet bandwidth limitations, and a lack of ISP reconfiguration and troubleshooting tools. We propose HomeVisor, a novel remote home network management tool. In this paper, we evaluate HomeVisors ability to outsource control to an entity outside the home network. This includes the overhead of multiple slices within the home, and the effect of controller latency on network performance.

Stitching Inter-Domain Paths over IXPs

Modern Internet applications, from HD video-conferencing to health monitoring and remote control of power-plants, pose stringent demands on network latency, bandwidth and availability. An approach to support such applications and provide inter-domain guarantees, enabling new avenues for innovation, is using centralized inter-domain routing brokers. These entities centralize routing control for mission-critical traffic across domains, working in parallel to BGP. In this work, we propose using IXPs as natural points for stitching inter-domain paths under the control of inter-domain routing brokers. To evaluate the potential of this approach, we first map the global substrate of inter-IXP pathlets that IXP members could offer, based on measurements for 229 IXPs worldwide. We show that using IXPs as stitching points has two useful properties. Up to 91% of the total IPv4 address space can be served by such inter-domain routing brokers when working in concert with just a handful of large IXPs and their associated ISP members. Second, path diversity on the inter-IXP graph increases by up to 29 times, as compared to current BGP valley-free routing. To exploit the rich path diversity, we introduce algorithms that inter-domain routing brokers can use to embed paths, subject to bandwidth and latency constraints. We show that our algorithms scale to the sizes of the measured graphs and can serve diverse simulated path request mixes. Our work highlights a novel direction for SDN innovation across domains, based on logically centralized control and programmable IXP fabrics.

OpenCache: Leveraging SDN to demonstrate a customisable and configurable cache

Efficient content delivery is a constantly evolving challenge on the modern Internet. Reducing the impact of duplicate deliveries of identical content is a key factor in reducing congestion and transit costs for smaller networks. This work leverages SDN concepts and mechanisms in order to transparently store and deliver content from a local cache to the client, thus lightening the load on the WAN and relieving the necessity for urgent network capacity upgrades. An open interface to the cache presents owners with new possibilities for cache control and maintenance. This demonstration showcases a prototype implementation in action on a large-scale OpenFlow testbed deployed across Europe.

A collaborative AAA architecture to enable secure real-world network mobility

Mobile Networks are emerging in the real world in various scenarios, from networks in public transportation to personal networks in consumer electronics. The NEMO BS protocol provides constant network connectivity and reachability for the nodes of these Mobile Networks in a seamless manner despite their roaming. However, NEMO BS has yet to show its advantages in real world deployment because it lacks troublefree and secure network access for the whole network, and secure data transmission for the nodes it provides connectivity for. On the other hand, Access Networks provide connectivity for Mobile Networks, but currently lack a robust AAA service which would enable network mobility support in a fast, trouble-free, but also secure and authenticated manner. Our paper describes a collaborative Unified Architecture that satisfies the requirements of both Mobile Networks and Access Networks, and our evaluation proves its efficiency and applicability for real world deployment in todays Internet infrastructure.

Towards a secure and seamless host mobility for the real world

Mobile IPv6 has been developed for quite a few years now, but it has yet to bring its constant connectivity and global reachability benefits to mobile devices in real world scenarios, mainly due to lack of trouble-free and secure network access and data transmission for devices as they roam. In this paper we propose a Unified Architecture that combines the strengths of Mobile IPv6 and AAA services and closes the gap between the Mobile Node and the Access Networks requirements. Our approach provides a comprehensive solution in a setting where users require seamless roaming, secure network access and secure data transmission in a dynamic fashion as they commute, whereas Access Networks require powerful AAA services without compromising their security policies. The qualitative and quantitative evaluation of our Unified Architecture through thorough laboratory tests, demonstrate the efficiency of our approach and highlight its potential and suitability for real world deployment in the current Internet architecture.

Location Awareness Rescue System: Support for Mountain Rescue Teams

Aiding the efficient collaboration and coordination of rescue teams is a difficult task especially in a mountainous region. Challenges emerge from quickly alerting and debriefing rescuers, to deploying them effectively, and also coordinating and monitoring them in the rural search domain. Knowing the exact location of the rescuers and vehicles involved in a mountain search and rescue mission is a key element for the successful progress of the mission and aids the mission coordinator, who usually stays at the headquarters, to take fast and informed decisions. In this paper we present the devised Location Awareness Rescue System that targets the aforementioned challenges, and provides location information and updates of the rescuers in a real time manner as they are deployed in the rescue domain overlaid onto interactive maps. The results from our tests show that our system is a proficient presence management solution that can provide precise location information by recovering from any periodic or total connectivity loss, and also improve and support mountain rescue teams leading to more effective and successful missions.

Intelligent autonomous handover in iMANETs

Autonomously making good network handover decisions is a complicated process that is fundamentally important in many complex mobile scenarios. In many mobile scenarios it is often infeasible to assume that an end user can be required to intervene and manually perform or verify a network handover decision. For this reason, utilities are required that can specifically manage the network connectivity of mobile nodes, monitoring their constantly changing state and the changing environment around them in order to ensure that the most appropriate connection is utilised at any given time. In this paper we present our Handover Manager that we have developed specifically for use in rescue system mobile networking solutions, such as mountain and coastal rescue, based on our experiences from real use case deployments. In particular we describe the way our solution autonomously manages connections to multiple heterogeneous access network technologies, we provide results from a testbed based analysis we performed and finally we draw upon our experiences to highlight important areas for future consideration that are applicable to our Handover Manager approach and to the wider MANET community in general.

Towards SDN based queuing delay estimation

As one of QoS (Quality of Service) metrics, delay is critical important to delay sensitive applications, such as interactive video, network game and online surgery. In this paper, we exploit SDN (Software Defined Networking) advantages to solve delay QoS problem. Our work mainly focuses on SDN based queuing delay estimation with real traffic and end-to-end delay control. First, we propose a queuing estimation model and extended it for end-to-end delay of the whole path. It is proved to be feasible and accurate with experimental results in SDN environment. Second, in order to demonstrate the use of our proposed model, we also implement an end-to-end delay control application in SDN. It fulfills specific delay QoS requirements by dynamically switching flows to a suitable queue based on estimation results and delay requirements.