Nicola Blefari Melazzi

Check before storing: what is the performance price of content integrity verification in LRU caching?

In some network and application scenarios, it is useful to cache content in network nodes on the fly, at line rate. Resilience of in-network caches can be improved by guaranteeing that all content therein stored is valid. Digital signatures could be indeed used to verify content integrity and provenance. However, their operation may be much slower than the line rate, thus limiting caching of cryptographically verified objects to a small subset of the forwarded ones. How this affects caching performance? To answer such a question, we devise a simple analytical approach which permits to assess performance of an LRU caching strategy storing a randomly sampled subset of requests. A key feature of our model is the ability to handle traffic beyond the traditional Independent Reference Model, thus permitting us to understand how performance vary in different temporal locality conditions. Results, also verified on real world traces, show that content integrity verification does not necessarily bring about a performance penalty; rather, in some specific (but practical) conditions, performance may even improve.

Streamline: An Optimal Distribution Algorithm for Peer-to-Peer Real-Time Streaming

In this paper, we propose and evaluate an overlay distribution algorithm for P2P, chunk-based, streaming systems over forest-based topologies. In such systems, the stream is divided in chunks; chunks are delivered by each node in a store-and-forward way. A relaying node starts distributing a chunk only when it has completed its reception from another node. Peers are logically organized in a forest of trees, where each tree includes all peers. The source periodically distributes different chunks to each tree for their delivery. Our key idea consists in employing serial transmission: for each tree, and thus, for each chunk, the source node sends the chunk to its children in series; the same holds for each peer node of the tree, excluding the leaves. Besides this basic idea, the contributions of this paper are: 1) we demonstrate the feasibility of serial transmission over a forest of trees, which is not a trivial problem, unlike the case of parallel transmission; 2) we derive an analytical model to evaluate the system performance; 3) we derive a theoretical bound for the number of nodes reachable in a given time interval or equivalently for the time required to reach a given number of nodes; 4) we prove the optimality of our approach in terms of its capability to reach such bound; and 5) we develop a general simulation package for P2P streaming systems and use it to compare our solution to literature results. Finally, we stress that this paper is focused on the theoretical properties and performance understanding of the proposed distribution algorithm, rather than on its practical implementation in a real system. However, we also briefly describe a practical workable implementation of our algorithm.

Exploiting content centric networking to develop topic-based, publish–subscribe MANET systems

Abstract Mobile Ad-hoc NETworks (MANETs) connect mobile wireless devices without an underlying communication infrastructure. Communications occur in a multi-hop fashion, using mobile devices as routers. Several MANET distributed applications require to exchange data (GPS position, messages, pictures, etc.) by using a topic-based publish–subscribe interaction. Participants of these applications can publish information items on a given topic (identified by a name) and can subscribe to a topic to receive the related published information. An efficient dissemination of publish–subscribe data in MANET environments demands for robust systems, able to face radio resource scarcity, network partitioning, frequent topology changes. Many MANET publish–subscribe systems have been proposed so far in the literature assuming an underlying TCP/IP network. In this paper, we discuss the benefits of building a MANET publish–subscribe system exploiting Content Centric Networking (CCN) technology, rather than TCP/IP. We show how CCN functionality, such as in-network caching and multicasting can be used to achieve an efficient and reliable data dissemination in MANET environments, including the support of delay tolerant delivery. We present different design approaches, describe our topic-based publish–subscribe CCN system, and report the results of a performance evaluation study carried out with real software in an emulated environment. The emulation environment is based on Linux virtual machines. The performance evaluation required also a CCN MANET routing engine, which we developed as a plug-in of the OLSR Linux daemon.

Modeling multipath forwarding strategies in Information Centric Networks

A content can be replicated in more than one node in Information Centric Networks (ICNs). Thus, more than one path can be followed to reach the same content, and it is necessary to decide the interface(s) to be selected in every network node to forward content requests towards such multiple content containers. A multipath forwarding strategy defines how to perform this choice. We propose a general analytical model to evaluate the effect of multipath forwarding strategies on the performance of an ICN content delivery, whose congestion control follows a receiver driven, path-unaware, loss-based AIMD scheme. We use the model to understand the behavior of ICN multipath forwarding strategies proposed in the literature so far, and to devise and evaluate a novel strategy.

On the Fly TCP Acceleration with Miniproxy

TCP proxies are basic building blocks for many advanced middleboxes. In this paper we present Miniproxy, a TCP proxy built on top of a specialized minimalistic cloud operating system. Miniproxys connection handling performance is comparable to that of full-fledged GNU/Linux TCP proxy implementations, but its minimalistic footprint enables new use cases. Specifically, Miniproxy requires as little as 6 MB to run and boots in tens of milliseconds, enabling massive consolidation, on-the-fly instantiation and edge cloud computing scenarios. We demonstrate the benefits of Miniproxy by implementing and evaluating a TCP acceleration use case.

Internames: A name-to-name principle for the future Internet

Information Centric Networking (ICN), a novel network paradigm, places the focus on the content instead of the end-hosts. ICN addresses content by names instead of locations and can ease content retrieval and improve network efficiency. Ongoing work attempts to extend the use of ICN to scenarios such as real time communication, group communication, push services, and addresses the issue of migration from the current network and coexistence of different network paradigms. In this work, we argue that by extending the current design of ICN from a “host-to-name” to a “name-to-name” architecture, the utility and efficiency of ICN could be further increased. We propose Internames, an architectural framework in which names are used to identify all entities involved in communication: content, users, devices, logical points, and services. Internames is envisioned to be an overarching name-to-name communication primitive that is fully compatible with ICN principles, accommodates the coexistence (or gradual migration) of different network realms (e.g., IP, ICN, VANET) and is suitable for application scenarios where ICN is somehow limited by its reliance on a “host-to-name” approach. In this paper, we provide early insights into the Internames architecture by leveraging on the work done by the research community and identify components and challenges that require more detailed investigation.

Towards fully IP-enabled IEEE 802.15.4 LR-WPANs

This extended abstract describes a poster and a proposal for demonstration. Its focus is on low rate wireless personal area networks (LR-WPANs) which use IEEE 802.15.4 physical and MAC layers at the lower layers of the protocol stack. More precisely, goal of this extended abstract is to present a real test-bed, whose main goal is to demonstrate how IEEE 802.15.4 LR-WPANs can fully inter-operate with IP networks. To this end, the protocol stack implemented at each IEEE 802.15.4 node includes the so said LoWPAN adaptation layer, which has been defined by the IETF 6LoWPAN working group. Moreover, we will present a possible practical solution for the problem of how to realize a gateway between the IEEE 802.15.4 LR-WPANs and the IP networks.

On the IP support in IEEE 802.15.4 LR-WPANs: Self-configuring solutions for real application scenarios

Due to the lack of IP support, the ZigBee protocol stack for IEEE 802.15.4 low rate wireless personal area networks (LR-WPANs) is the perfect solution for closed, ad-hoc environments. However, we can envisage also open and interconnected application scenarios, such as the Internet of Things or the integration of ZigBee/IEEE 802.15.4 nodes in mobile/smart phones, that would greatly benefit from the IP support. The LoWPAN adaptation layer proposed by the 6LoWPAN IETF working group to enable the transmission/reception of IPv6 data in IEEE 802.15.4 networks may be regarded as the first step towards the direction of IP direct support into IEEE 802.15.4 nodes. However, a fully fledged solution to be used in the scenarios outlined above still lacks the following functionality: i) self-configuring address assignment mechanism; ii) multi-hop routing protocol; iii) support of Internet-compliant transport protocols; iv) self-configuring network and service discovery. It may seem trivial to provide such functionality in an IP world, as off the shelf solutions could be adopted; however, this is not an easy task, given the very limited hardware capabilities of IEEE 802.15.4 devices. In this paper we define a complete protocol architecture and specific self-configuring mechanisms to support the aforementioned functionality over IEEE 802.15.4 devices, taking into account their hardware constraints. We also present an implemented test-bed which demonstrates the functionality of the proposed solution in a real application scenario. 1.

CONVERGENCE: Extending the Media Concept to Include Representations of Real World Objects

The Information Society relies on an increasingly diverse mass of digital information, a trend accentuated by the Internet of Things in which Real World Objects (RWOs) have their own Resource Identifiers and related data. In this setting, the goals of the CONVERGENCE framework are to enhance current media handling with new functionality and extend the traditional concept of media to include digital representations of RWOs. The CONVERGENCE framework is based on the concept of Versatile Digital Item (VDI), a structured package of digital content and meta-information, inspired by the MPEG-21 standard but designed to address a broader range of application domains, including the management of RWOs in the Internet of Things. The VDI is supported by an innovative middleware and by tools and applications. The CONVERGENCE framework incorporates six innovations: (1) VDIs provide uniform mechanisms to handle different classes of information, including RWOs; (2) VDIs are intrinsically dynamic, allowing both providers and consumers to update content; (3) VDIs support “digital forgetting” (automatic “un-publishing,” automated garbage collection of VDIs after a user-defined expiry date); (4) VDIs meet security and privacy needs of both professional and nonprofessional consumers and providers; (5) VDIs support new modes of semantic search; (6) VDIs allow easy sharing of information across multiple, heterogeneous devices. In this chapter, we present the CONVERGENCE framework, its main concepts and ideas, some proposals to make it real, and some use cases and we show how our proposed concept can be a fundamental enabler for the Internet of Things.

Popularity Proportional Cache Size Allocation policy for video delivery on CCN

Content Centric Networking (CCN), which is regarded as an innovational architecture of future network, is increasingly gaining attention in recent years. Based on the observation of current Internet usage, CCN presents a content-centric model which focuses on data distribution and retrieval. To enhance the efficiency of content distribution, In-network caching is adopted, which enables routers to temporarily store the passing by data. Thus the scheme of cache management will affect the network performance significantly. In this paper, a cache replacement policy named Popularity Proportional Cache Size Allocation (PPCSA) policy has been proposed, which designed for video content delivery on CCN. Unlike other previous works in this area, which have focused on the popularity of individual content chunks, in this study, we not only consider the title-level popularity of a video which is composed of a set of video segments, but also take the chunk-level probability of video segments within a video title into consideration. We evaluated our policy through simulations, by using a simple 4-level tree topology and a real network based hybrid topology. The results validate that on both scenarios, the proposed approach can increase the average cache hit ratio and shorten the average content delivery distance between requesters and object contents. In addition, we analyzed the energy efficiency of PPCSA policy, and we found that compared to other three cache replacement policies, Least Recently Used (LRU), Least Frequently Used (LFU) and First in First out (FIFO), PPCSA reduced the transmission energy consumption, and improved the energy efficiency in idle time.