Overlay, Boruvka-Based, Ad-Hoc Multicast Protocol: Description and Performance Analysis

This paper presents a novel MANET multicast protocol, named overlay Boruvka-based ad-hoc multicast protocol (OBAMP), and evaluates its performance. OBAMP is an overlay protocol: it runs only in the end-systems belonging to the multicast group. User data are distributed over a shared distribution tree formed by a set of non-cyclic UDP tunnels. OBAMP derives the distribution tree by approximating the Boruvka algorithm; the Boruvka algorithm is a classical tool (1926) to find the minimum spanning tree; thus, the distribution tree of OBAMP is an approximation of the minimum spanning tree of the connectivity topology at hand. OBAMP shows three distinctive advantages: i) its distribution tree closely resembles the minimum spanning tree; ii) it exploits broadcast communications (with favourable consequences on its efficiency); iii) its design takes into account not only overlay signalling but also network-layer signalling; thus, the protocol succeeds in limiting the overall signalling load, network+overlay. As a consequence, OBAMP has a low-latency and a high delivery ratio, even when the group size increases. To prove this statement, we analyze the performance of OBAMP with ns-2 and compare it with two state-of-the-art protocols, namely ODMRP (a network-layer protocol) and ALMA (an overlay protocol). Both OBAMP and ALMA are assumed to use AODV as underlying routing protocol. Also, we stress that we have implemented OBAMP, in Java, and we have tested it on the field, to prove its feasibility. To allow fellow researchers to reproduce and test our work we published all simulation and implementation codes, in www.radiolabs.it/obamp.