The research activity is focused on the study of the DTN (Delay-/Disruption-Tolerant Networking) architecture and related protocols (Bundle Protocol, Licklider Transmission Protocol) in the space environment, including both the Inteplanetary Internet and satellite communications (GEO & LEO constallations). The same architecture can be applied to all "challenged networks" (emergancy telecommunications, sensor networks, tactical military communications, UAVs, VANETs, underwater communications, communications in area lacking a TLC infrustructure), where the TCP/IP architecture and protocols cannot operate. the DTN applications to smart phones, including the development of DTN apps, is also matter of study.
The research on these topics has a twofold aim: first, the performance evaluation of DTN protocols, routing algorithms and architecture, aimed at finding and implementing possible improvements; second, the development of software tools specifically designed for the evaluation of DTN performance.
Concerning the first aim, the most recent research has investigated the performance of CGR (Contact Graph Routing) algorithm, designed by NASA-JPL, and has led to the proposal of a few enhancements, now included in the official version. Analogously for the LTP protocol, whose performance in the presence of a high loss ratio has been improved. Recently, the application of FEC codes working on LTP segments has been investigated in collaboration with the German Aerospace Centre, DLR. Other studies have evaluated DTN performance in Mars communications or with the far side of the Moon. In a recent past, the research has investigated the performance of TCP variants in GEO satellite environments, for which a specialized variant, TCP Hybla, has been designed and implemented. Hybla is included in the set of the ten experimental variants present in the official GNU-Linux kernel and can easily selected by the user to override the default. Linked to Hybla research, is the study of PEPs (Performance Enhancing Proxies) and the PEPsal development, the sole TCP-splitting PEP avaialable as free software.
The previous activity would not have been possible without the parallel development of software tools for carrying out the experiments and evaluate the performance. In particular, we remember DTNperf, whose third version is now included in ION, the suite of DTN protocols developed and maintained by NASA-JPL (released as free software too). DTNperf_3 has been extensively used in spring 2015 to carry out a series of interoperability test between the ION and DTN2 implementations of the bundle protocol, carried out jointly by NASA and JAXA (the Japanese space agency), in the framework of CCSDS standardization.
Another essential tool for experiment execution, resulting from research, is Virtualbricks, a virtual testbed manager for GNU-Linux, based on KVM for virtual machines and VDE (Virtual Distributed Ethernet, a package developed by Prof. Renzo Davoli of DISI of University of Bologna) for their interconnections. In brief, with this tool is possible to carry out complex tests involving many machines, in a fast and simple way, by exploiting our PC has the sole hardware support. Virtualbricks is widely used in the development of experimental thesis and as a teaching tool, as in practice it provides the user with a virtual lab for networking studies.
The present research activity takes advantage of formal or informal cooperation with NASA-JPL, ESA, DLR and University of Genoa.
