The XO-Mesh path discovery mechanism sanity

The XO-Mesh is a layer two ad hoc multlhop wireless network, developed by OLPC for its hundred-dollar educational laptop. Although based on an early version of the IEEE 802.11s draft, both proposals diverged in many aspects as they evolved in the last three years. This article focuses on the Path Discovery Mechanism introduced by OLPC, which differs from the mechanism described in the IEEE 802.11s — the Hybrid Wireless Mesh Protocol (HWMP) — in many aspects. We are particularly interested in explaining odd behaviors observed in the field (OLPC deployments) and test beds — namely the forming of unexpected multihop paths. We confirm that such oddities do occur and propose methods to reduce its effects.