  Unlike traditional routing procedures that, at the best, single out a unique
route, multi-path routing protocols discover proactively several alternative
routes. It has been recognized that multi-path routing can be more efficient
than traditional one mainly for mobile ad hoc networks, where route failure
events are frequent. Most studies in the area of multi-path routing focus on
heuristic methods, and the performances of these strategies are commonly
evaluated by numerical simulations. The need of a theoretical analysis
motivates such a paper, which proposes to resort to the terminal-pair routing
reliability as performance metric. This metric allows one to assess the
performance gain due to the availability of route diversity. By resorting to
graph theory, we propose an analytical framework to evaluate the tolerance of
multi-path route discovery processes against route failures for mobile ad hoc
networks. Moreover, we derive a useful bound to easily estimate the performance
improvements achieved by multi-path routing with respect to any traditional
routing protocol. Finally, numerical simulation results show the effectiveness
of this performance analysis.
