Neighbor discovery message hold times for MANETs

We present the results of an experimental study that was designed to understand the impact of neighbor discovery (ND) message hold times on the performance of mobile ad hoc networks. Experiments were conducted on a physical testbed of pseudo-mobile nodes and an NS-3 based simulator. The results of these experiments indicate that setting the ND message hold time 25% to 100% larger than the ND message interval provides favorable performance; or 2  s larger on an absolute scale. In particular, that hold time provides the best trade-off between two sources of packet loss induced by the neighbor discovery process: misrouting and neighbor-flapping. The precise absolute value required is system dependent and therefore we discuss how to derive it in general. To nearly eliminate neighbor-flapping, the ND message hold time needs to be set to slightly greater than twice the value of the ND message interval (i.e.,  >  100% larger) to protect against the occurrence of a single isolated lost ND message.