On the robustness of the OLSR protocol under unwanted interference

Abstract

Optimized Link State Routing (OLSR) is a popular protocol for proactively establishing peer-to-peer links in mobile ad hoc networks (MANETs). Protocol ‘hello’ messages between neighbouring nodes establish link connections that are used to route information from a source via multiple relays to ultimately reach destinations that would not otherwise be directly connected to that source. The ‘hello’ messages are sent periodically with a random timing jitter in order to avoid collisions with messages of other neighbouring nodes such that the connection integrity of the MANET, and thus network availability, remain high. In this paper we explore the robustness of the OLSR protocol under unwanted interference that causes a denial of service. We simulate the denial of service with a statistical method, targeting the ‘hello’ messages with unwanted interference, and measure the mean time between failure and percent ‘connectedness’ of a network link. Our results show that the commercial off-the-shelf implementations of the OLSR protocol are not resilient to unwanted interference leading a MANET to potential denial or degradation if its routing protocol were targeted. We conclude that a randomized jitter in OLSR ‘hello’ message periodicity is an important element in avoiding this unwanted interference.