A Study of Local Connectivity Maintenance Strategies of MANET Reactive Routing Protocol Implementations

One of the features of a MANET routing protocol with significant influence on network performance is local connectivity maintenance (LCM). This is an important task which aims at monitoring the availability of links used in an on-going communication. Many MANET routing protocol specifications define a range of layer two and layer three approaches for detecting link breaks. Simulation based MANET studies mainly consider layer two LCM approaches, while most real world routing protocol implementations use layer three LCM mechanisms. In this paper we present our experience evaluating the impact of LCM strategies of real world routing protocol implementations on route change latency, bandwidth and power consumption in a number of scenarios. In particular, we test the Hello message mechanism in AODV-UU implementation, the software ACK scheme in DSR-UU implementation and the link layer notification included in the authors' NST-AODV implementation for TinyOS devices. Results provide a reference on the achievable performance with each approach.