OLSR and MPR: Mutual Dependences and Performances

Optimized Link State Routing protocol (OLSR) is one promising routing protocol for mobile ad hoc networks. It recently reached the RFC step and is still under improvement before becoming a standard. Since its first design, OLSR has been associated with the Multipoint Relay (MPR) protocol to reduce the flooding of OLSR topological messages. Many papers has been written on possible promising solutions to improve OLSR by replacing MPR by another topology control protocol, modifying MPR heuristic, or adapting OLSR to fast mobility and include security. But few papers have dealt with the interactions between MPR and OLSR and what makes them so particular. In this paper, we analyze OLSR requirements and MPR properties and show that OLSR optimality is bound to the deep cooperation and interaction between MPR and OLSR. We specifically exhibit the intrinsic properties of MPR absolutely necessary to OLSR, and that cannot be found in any other topology control protocol at this time. Conversely, we illustrate how OLSR is able to correct MPR’s drawbacks to reach its objective. We also show that OLSR suffers from convergence problems that are commonly dealt with adequate configuration parameters as suggested in the RFC3626. Finally, we suggest that any attempt to alter any of the two protocols, or their respective configuration parameters, will lead to suboptimal results.