Xenofon Vasilakos

A Survey of Information-Centric Networking Research

The current Internet architecture was founded upon a host-centric communication model, which was appropriate for coping with the needs of the early Internet users. Internet usage has evolved however, with most users mainly interested in accessing (vast amounts of) information, irrespective of its physical location. This paradigm shift in the usage model of the Internet, along with the pressing needs for, among others, better security and mobility support, has led researchers into considering a radical change to the Internet architecture. In this direction, we have witnessed many research efforts investigating Information-Centric Networking (ICN) as a foundation upon which the Future Internet can be built. Our main aims in this survey are: (a) to identify the core functionalities of ICN architectures, (b) to describe the key ICN proposals in a tutorial manner, highlighting the similarities and differences among them with respect to those core functionalities, and (c) to identify the key weaknesses of ICN proposals and to outline the main unresolved research challenges in this area of networking research.

Caching and mobility support in a publish-subscribe internet architecture

The Internet is straining to meet demands that its design never anticipated, such as supporting billions of mobile devices and transporting huge amounts of multimedia content. The publish-subscribe Internet (PSI) architecture, a clean slate information-centric networking approach to the future Internet, was designed to satisfy the current and emerging user demands for pervasive content delivery, which the Internet can no longer handle. This article provides an overview of the PSI architecture, explaining its operation from bootstrapping to information delivery, focusing on its support for network layer caching and seamless mobility, which make PSI an excellent platform for ubiquitous information delivery.

Proactive selective neighbor caching for enhancing mobility support in information-centric networks

We present a Selective Neighbor Caching (SNC) approach for enhancing seamless mobility in ICN architectures. The approach is based on proactively caching information requests and the corresponding items to a subset of proxies that are one hop away from the proxy a mobile is currently connected to. A key contribution of this paper is the definition of a target cost function that captures the tradeoff between delay and cache cost, and a simple procedure for selecting the appropriate subset of neighbors which considers the mobility behavior of users. We present investigations for the steady-state and transient performance of the proposed scheme which identify and quantify its gains compared to proactively caching in all neighbor proxies and to the case where no caching is performed. Moreover, our investigations show how these gains are affected by the delay and cache cost, and the mobility behavior.

On inter-domain name resolution for information-centric networks

Information-centric networking (ICN) is a paradigm that aims to better reflect current Internet usage patterns by focusing on information, rather than on hosts. One of the most critical ICN functionalities is the efficient resolution/location of information objects i.e., name resolution. The vast size of the information object namespace calls for a highly scalable and efficient name resolution approach. Currently proposed solutions either rely on a DHT structure, thus ensuring load balancing and scalability at the cost of inefficient routing, or on hierarchical structures, thus preserving routing efficiency at the cost of limited scalability. In this paper, we study in detail the tradeoff between state/signaling overhead versus routing efficiency for a generic name-resolution system based on a novel DHT scheme with enhanced routing properties, and compare it to DONA, an ICN architecture based on hierarchical resolution and routing.

Efficient proactive caching for supporting seamless mobility

We present a distributed proactive caching approach that exploits user mobility information to decide where to proactively cache data to support seamless mobility, while efficiently utilizing cache storage using a congestion pricing scheme. The proposed approach is applicable to the case where objects have different sizes and to a two-level cache hierarchy, for both of which the proactive caching problem is hard. Our evaluation results show how various system parameters influence the delay gains of the proposed approach, which achieves robust and good performance relative to an oracle and an optimal scheme for a flat cache structure.

Addressing niche demand based on joint mobility prediction and content popularity caching

We present an efficient mobility-based proactive caching model for addressing niche mobile demand, along with popularity-based and legacy caching model extensions. Opposite to other proactive solutions which focus on popular content, we propose a distributed solution that targets less popular, personalised or dynamic content requests by prefetching data in small cells based on aggregated user mobility prediction information. According to notable studies, niche demand, particularly for video content, represents a significant 20-40% of Internet demand and follows a growing trend. Due to its novel design, our model can directly address such demand, while also make a joint use of content popularity information with the novelty of dynamically tuning the contribution of mobility prediction and content popularity on local cache actions.Based on thorough performance evaluation simulations after exploring different demand levels, video catalogues and mobility scenarios including human walking and automobile mobility, we show that gains from mobility prediction can be high and able to adapt well to temporal locality due to the short timescale of measurements, exceeding cache gains from popularity-only caching up to ź41% for low caching demand scenarios. Our models performance can be further improved at the cost of an added computational overhead by adapting cache replacements by, e.g. in the aforementioned scenarios, ź41%. Also, we find that it is easier to benefit from requests popularity with low mobile caching demand and that mobility-based gains grow with popularity skewness, approaching close to the high and robust gains yielded with the model extensions.

Cloud Computing for Global Name-Resolution in Information-centric Networks

Information-Centric Networking (ICN) is a novel paradigm for future Internet architectures. It exploits the current trend in Internet usage which mostly involves information dissemination. ICN architectures based on the publish/subscribe model use names for information in order to route requests and data, as well as to facilitate in-network caching, anycasting and multicasting for efficient content delivery. However, the number of named information objects is expected to be huge in the future Internet, raising serious concerns with respect to a global-scale deployment of ICN. Routing and forwarding will require vast amounts of state, which pushes storage, maintenance and processing demands to the limit. In this paper we discuss the feasibility of deploying the Data Oriented Networking Architecture (DONA) by leveraging cloud computing facilities. We identify the exact scalability concerns for DONA based on simulations over a realistic model of the current Internet topology and find that registrations for information objects lead to a state explosion. For this reason, we then discuss how cloud facilities can assist DONA deployment, focusing on various options for deploying DONA in the cloud and their suitability for different areas of the inter-network.

Supporting mobility in a publish subscribe internetwork architecture

Information-Centric Networking (ICN) is constantly gaining momentum within the Future Internet research community. In the PURSUIT research project we are developing a clean-slate Pub/Sub Internetworking (PSI or Ψ) approach with integrated seamless mobility support. The novel ICN mechanisms supported in Ψ, along with smartly placed in-network caches, enable the architecture to handle both mobile and fixed devices in a uniform way. This paper presents a blueprint for optimizing mobility support in Ψ without modifications to the architecture or add-on solutions. We demonstrate a micro-mobility scenario that describes the functionality of Ψs core components in supporting mobility and then sketch our plans for future work and a proper assessment of these designs.

On the inter-domain scalability of route-by-name Information-Centric Network Architectures

Name resolution is at the heart of Information-Centric Networking (ICN), where names are used to both identify information and/or services, and to guide routing and forwarding inside the network. The ICN focus on information, rather than hosts, raises significant concerns regarding the scalability of the required Name Resolution System (NRS), especially when considering global scale, inter-domain deployments. In the route-by-name approach to NRS construction, name resolution and the corresponding state follow the routing infrastructure of the underlying inter-domain network. The scalability of the resulting NRS is therefore strongly related to the topological and routing characteristics of the network. However, past work has largely neglected this aspect. In this paper, we present a detailed investigation and comparison of the scalability properties of two route-by-name inter-domain NRS designs, namely, DONA and CURLING. Based on both real, full-scale inter-domain topology traces and synthetic, scaled-down topologies, our work quantifies a series of important scalability-related performance aspects, including the distribution of name-resolution state across the Internet topology and the associated processing and signaling overheads. We show that by avoiding DONAs exchange of state across peering links, CURLING results in deployment costs proportional to the total number of downstream customers of each Autonomous System. This translates to a 62-fold global state size reduction, at the expense of a 2.78-fold increase in lookup processing load, making CURLING a feasible approach to ICN name resolution.

NAMED ENTITY RECOGNITION IN GREEK TEXTS WITH AN ENSEMBLE OF SVMS AND ACTIVE LEARNING

We present a freely available named-entity recognizer for Greek texts that identifies temporal expressions, person, and organization names. For temporal expressions, it relies on semi-automatically produced patterns. For person and organization names, it employs an ensemble of Support Vector Machines that scan the input text in two passes. The ensemble is trained using active learning, whereby the system itself proposes candidate training instances to be annotated by a human during training. The recognizer was evaluated on both a general collection of newspaper articles and a more focussed, in terms of topics, collection of financial articles.