*4.1.3. Hybrid routing protocol*

The hybrid is a protocol where a certain set of nodes, (only a limited number of nodes) periodically updates the information nodes / routes of possible destinations, and attempts to make a suitable use of the two previous approaches. Examples of hybrid protocols are : HWMP (Hybrid Wireless Mesh Protocol), ZRP (Zone Routing Protocol) and FSR (Fisheye State Routing); the HWMP protocol is the representative of the hybrid protocols used for the following tests of this chapter. HWMP is based on AODV [22] and also has an optional routing protocol, called RAOLSR (Radio Aware OLSR) based on OLSR [23] [24].

HWMP is a hybrid routing protocol. It has both re-active and proactive components. The creation of HWMP is an adaptation of AODV to radio-aware link metrics and MAC addresses. It is the basic, reactive component of HWMP. The on-demand path setup is achieved through the path discovery mechanism that is very similar to that of AODV. If a mesh point needs a path to the destination, it broadcasts a path request message (PREQ) into the mesh network. The hybrid routing protocols combine the best features.
