Marco Cello

A survey of architectures and scenarios in satellite‐based wireless sensor networks: system design aspects

This paper is not a survey related to generic wireless sensor networks (WSNs), which have been largely treated in a number of survey papers addressing more focused issues; rather, it specifically addresses architectural aspects related to WSNs in some way connected with a satellite link, a topic that presents challenging interworking aspects. The main objective is to provide an overview of the potential role of a satellite segment in future WSNs. In this perspective, requirements of the most meaningful WSN applications have been drawn and matched to characteristics of various satellite/space systems in order to identify suitable integrated configurations. Copyright

Statistical fingerprint-based intrusion detection system (SF-IDS)

Summary Intrusion detection systems (IDS) are systems aimed at analyzing and detecting security problems. The IDS may be structured into misuse and anomaly detection. The former are often signature/rule IDS that detect malicious software by inspecting the content of packets or files looking for a “signature” labeling malware. They are often very efficient, but their drawback stands in the weakness of the information to check (eg, the signature), which may be quickly dated, and in the computation time because each packet or file needs to be inspected. The IDS based on anomaly detection and, in particular, on statistical analysis have been originated to bypass the mentioned problems. Instead of inspecting packets, each traffic flow is observed so getting a statistical characterization, which represents the fingerprint of the flow. This paper introduces a statistical analysis based intrusion detection system, which, after extracting the statistical fingerprint, uses machine learning classifiers to decide whether a flow is affected by malware or not. A large set of tests is presented. The obtained results allow selecting the best classifiers and show the performance of a decision maker that exploits the decisions of a bank of classifiers acting in parallel.

Combined Congestion Control and Link Selection Strategies for Delay Tolerant Interplanetary Networks

In view of the dense and complex space network topologies envisioned for the future, the management of congestion control is a prominent issue that deserves a particular attention. Given the challenging peculiarities of interplanetary environments, this paper focuses on the advantages offered by storage-based routing and on potentials of implementing Random Early Detection (RED) and Explicit Congestion Notification (ECN) mechanisms within the Delay Tolerant Network (DTN) architecture. In this light, solutions relying upon the aforementioned concepts have been designed and tested. Preliminary results show that combination of RED and ECN schemes with network-selection strategies for storage-based routing is really promising and outperforms other solutions in terms of reliability, network resource utilisation and power consumption.

JumpFlow: Reducing flow table usage in software-defined networks

Abstract The forwarding scheme in Software-Defined Networking (SDN) is usually coupled with flow table management. To reduce the redundancy in the flow tables of OpenFlow switches, some recent studies propose forwarding flows using stacked MPLS labels, in which each label in the stack indicates the forwarding decision at one hop of the forwarding route. However, using multiple MPLS labels in each packet introduces significant transmission overhead, especially in networks with large diameters. In this paper, we propose JumpFlow, a forwarding scheme that achieves low and balanced flow table usage in an SDN by properly and reactively placing flow entries on switches. To reduce the transmission overhead, JumpFlow uses the available VLAN identifier (VID) in the packet header to carry routing information. Constrained by the limited space of the VID, a flow’s complete routing information must be divided into several sections and loaded separately at different switches on the flow’s forwarding route. To achieve low and balanced flow table usage, we formulate and solve the reactive flow entry placement problem. We evaluate JumpFlow against the per-hop configuration-based forwarding of OpenFlow for both unicast and multicast scenarios in a real network topology with different traffic patterns. For the unicast scenario with different new flow arrival rates, JumpFlow postpones the time when the first flow rejection occurs, reduces the flow rejection percentage by 37.06%, and reduces the control messages for route configuration by 53.52% on average. For the multicast scenario with a high new multicast group arrival rate, JumpFlow increases the ratio of accepted multicast groups by 83.90%, and reduces the ratio of average control messages for a multicast group configuration by 32.68%.

A Model of Buffer Occupancy for ICNs

In this letter, an analytical framework to model nodes in Intermittently Connected Networks (ICNs) is proposed. A relationship is derived in the z-domain between the discrete probability densities of their buffer state occupancies and the sizes of the arriving bulks. Under a fixed epidemic-routing-based forwarding strategy, expressions are obtained for the average buffer occupancy and its standard deviation with immediate protocol advantages.

Evaluation of the Average Packet Delivery Delay in Highly-Disrupted Networks: The DTN and IP-like Protocol Cases

Delay/Disruption-Tolerant Networking (DTN) represents an innovative communication paradigm that enables the communication over Intermittently-Connected Networks (ICNs). ICNs are characterized by unpredictable or scheduled contacts among nodes, high latency, and high bit error rates. DTNs, unlike TCP/IP protocols, make use of store-and-forward techniques in order to cope with intermittent link issues. In this letter, a simple model is proposed to compute the average packet delivery delay in ICNs. Both the IP-like paradigm used by traditional TCP/IP protocols and DTN are considered. The results provide theoretical insights into the applications of these two approaches to ICNs. Numerical results and simulations are presented, too.

Mars to Earth communications through orbiters: Delay‐Tolerant/Disruption‐Tolerant Networking performance analysis

SUMMARY Delay-Tolerant/Disruption-Tolerant Networking (DTN) architecture will be used in future deep space missions, to enable autonomous networking operations and disruption-tolerant data communications. Therefore, it is worth analyzing the performance of the DTN Bundle Protocol (BP) in a realistic deep space environment, reproducing the characteristics of Mars missions. After a comprehensive introduction on data communications between Mars and Earth, the paper presents the essential features of both the BP DTN architecture and the Licklider Transmission Protocol (LTP), adopted here as BP convergence layer on deep space links, thanks to its ability to cope with the very long delays typical of this environment. The focus of our experiments is on analysis of the bundle flow from a Mars lander to an Earth control center through an intermediate relay node, for which two configurations are considered, inspired to Odyssey and Mars Reconnaissance Orbiter missions, respectively. Results are obtained by means of a test bed consisting of some GNU/Linux personal computers running either Interplanetary Overlay Network (ION) or DTN2 BP implementations. The analysis of results aims to highlight the role played by BP and LTP in tackling the challenges of Mars to Earth communications. Copyright

Structural properties of optimal coordinate-convex policies for CAC with nonlinearly-constrained feasibility regions

Necessary optimality conditions for Call Admission Control (CAC) problems with nonlinearly-constrained feasibility regions and two classes of users are derived. The policies are restricted to the class of coordinate-convex policies. Two kinds of structural properties of the optimal policies and their robustness with respect to changes of the feasibility region are investigated: 1) general properties not depending on the revenue ratio associated with the two classes of users and 2) more specific properties depending on such a ratio. The results allow one to narrow the search for the optimal policies to a suitable subset of the set of coordinate-convex policies.

BalCon: A Distributed Elastic SDN Control via Efficient Switch Migration

Scalability and reliability are among the main concerns in large-scale Software Defined Networking (SDN) application scenarios. A common approach is to use multiple distributed controllers, each managing one static partition of the network. In this paper, we show that dynamic mapping can improve efficiency in managing traffic load variations. We then propose BalCon (Balanced Controller): an algorithmic solution designed to tackle and reduce the load imbalance among SDN controllers through proper SDN switch migrations. Simulations demonstrate that BalCon is lightweight from the computational point of view and reduces the load imbalance among SDN controllers (expressed as variance) by 40% by migrating only a small number of switches. We also built a realistic prototype of SDN controller, BalConController, based on the open-source SDN framework RYU.

CAC with Nonlinearly-Constrained Feasibility Regions

Two criteria are proposed to characterize and improve suboptimal coordinate-convex (c.c.) policies in Call Admission Control (CAC) problems with nonlinearly-constrained feasibility regions. Then, a structural property of the optimal c.c. policies is derived. This is expressed in terms of constraints on the relative positions of successive corner points.