Network Management via Satellite - IEEE Xplore

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Network Management via Satellite. Franco Tommasi. Dept. of Innovation Engineering. University of Lecce, Italy. Email: [email protected]. Simone ...
Network Management via Satellite Franco Tommasi

Simone Molendini

Andrea Tricco

Dept. of Innovation Engineering University of Lecce, Italy Email: [email protected]

Dept. of Innovation Engineering University of Lecce, Italy Email: [email protected]

Dept. of Innovation Engineering University of Lecce, Italy Email: [email protected]

Abstract— Satellite links already provide Internet for multicast transmissions over large areas. It would be very useful to extend the traditional use of satellite applications to the management of networks. In this paper we show the evolution of the satellite platform which led us towards. We then report a novel protocol, the Centralized Signaling Protocol (CSP), which manages signalling messages to routers in terrestrial networks. Extensions to a reliable multicast protocol for transporting CSP via narrowband and long-duration satellite sessions are discussed. Several examples that illustrate the usage of the CSP are also provided.

I. I NTRODUCTION Since the year 2000 the University of Lecce and Clio S.r.L. have been working on several improvements to a network platform based on a GEO satellite link. The idea behind these efforts was to exploit the benefits provided by large footprints, natural multicast transmissions for Internet applications and topologically short distances between hosts. This resulted in various projects. The only application involved in the first project was Audio/Video (AV) over Internet. In the second project we integrated other multicast and unicast applications with it. A third project defined a multicast, reliable and secure transport, efficient when the satellite was the hub of the multicast tree. This protocol has turned out to be very useful for several applications, for example, we made use of it for transporting simultaneous uploads for router applications. In the light of this experience we realized that it would be very useful to extend the current use of Internet signalling applications. Several messages are needed to signalize, for instance, new multicast groups. We would like to reduce the complexity of such protocols by sending short messages via satellite to the involved routers. A satellite link is very useful because it can simultaneously reach several routers using few networks. The main benefits of a centralized use of the signalling are the ability to send a single message to several routers as well as the exploitation of the satellite as a backup link for terrestrial networks. It is particularly helpful when routers are under attack and it is very useful for reducing the complexity of Internet protocols from a decentralized to a centralized use. In this paper we discuss the use of signalling messages via satellite. In particular, we show extensions to a reliable multicast transport protocol for narrow-band and long-duration sessions. Moreover, we show a novel protocol, the Centralized Signaling Protocol (CSP), which manages signalling messages. Several examples that illustrate the usage of CSP are provided in Sec. IV.   

II. T HE EVOLUTION OF THE SATELLITE NETWORK U NIVERSITY OF L ECCE AND C LIO S. R .L

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For the purpose of introducing the role of satellite signalling, we here discuss the evolution of the use of the satellite with our platform. A. The MODUS project In the year 2000 an eLearning platform based on the integration of the satellite to the Internet was built [1]. In this platform AV was the only real-time application. It was transmitted by means of the satellite link - see Figure 1(a). AV flows were gathered by a “sender” host at the teacher’s side and relaunched to remote students. The satellite link was utilized to reach the students. Datagrams from the sender to a satellite gateway called “Sat GW” were transmitted in unicast since the Internet does not fully deploy multicast technology. B. The ESMEE project In the year 2002 the ESMEE project [2] improved MODUS. Significantly, ESMEE is the acronym of “Earth and Space Multimedia system - Enhancements and Extensions” - see Figure 1(b). First of all, the interactivity between the teacher and students was improved. A chat, an application which allows the synchronization of the student’s browser pages from a teacher’s and an electronic white-board was added. All these applications, including the the AV player, were integrated in the browser thus improving usability. A web-based Authentication, Authorization, Accounting and Billing (AAA&B) application allowed access to the system in a usable way. The quality of real-time traffic was monitored, improved and reserved. The Resource Reservation Protocol (RSVP) [3], a signalling protocol dedicated to Internet Quality of Service (QoS), was selected for signalling flows requirements. In particular, we added a QoS Manager module integrated in the hosts’ operating systems to intercept the opening and the closing of real-time flows necessary for triggering RSVP sessions in a natural way. This kind of quality was obtained end-to-end: for each flow two RSVP sessions were maintained, one in unicast from the sender to the Sat GW and one in multicast from the gateway to the routers at the receiving networks.

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C. The SRDP Protocol In the 2003 year we designed the Satellite Reliable Distribution Protocol (SRDP) [4]. SRDP enables reliable transmission of multicast flows. It was designed to meet the needs of broad diffusion of files via satellite. SRDP exploits both the network and the management applications of ESMEE - see Figure 1(c). We use SRDP in several projects. For instance, in the Land-Lab project, an IT support for archeology. Here the SRDP transmits bulk data to synchronizing databases with multimedia content installed in totems at several museums. It also supports eLearning sessions. The use of the SRDP in the Rete Unitaria della Pubblica Amministrazione Regionale - Puglia [7] (RUPAR-P - the common network of the regional public administration for Apulia) project for the Apulia region) has installed satellite receiving apparatus, including the satellite router, in more than a hundred municipalities in the south-east of Italy. Among others, we have developed an application based on SRDP that automatically adds and updates both operating system’s distributions and applications to several receivers at the same time. SATELLITE NETWORK FOR SIGNALLING THE I NTERNET

These projects had involved the installation of hundreds of satellite routers in both homes and buildings. Our results showed that on the receiving side, both outdoor (the dish, the LNB, the coaxial cable) and indoor (DVB interface) is cheap; a few hundreds euros. Moreover, we realized that the management of the satellite routers could be done by means of the satellite link, very useful, for instance, when upgrading the software of the router’s operating system contemporaneously. Using the satellite path rather than a terrestrial path is more secure, more efficient and   

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