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The Optimized Link State Routing Protocol (OLSR) is developed for mobile ad hoc networks. The protocol is documented in the experimental Request For Comment(RFC) 3626. OLSR is table-driven and pro-active and utilizes an optimization called Multipoint Relaying for control traffic flooding.
RFC3626 modularizes OLSR into core functionality, which is always required for the protocol to operate, and a set of auxiliary functions. This chapter presents the core functionality of OLSR. The core functionality specifies, in its own right, a protocol able to provide routing in a stand-alone MANET. Each auxiliary function provides additional functionality, which may be applicable in specific scenarios, e.g., in case a node is providing connectivity between the MANET and another routing domain. All auxiliary functions are compatible, to the extent where any auxiliary function may be implemented with the core. Furthermore, the protocol is said to allow heterogeneous nodes, i.e., nodes which implement different subsets of the auxiliary functions, to coexist in the network. As we shall later, this is not the case for all auxiliary functions.
It is important to understand that OLSR does not route traffic. It is not in any way responsible for the actual process of routing traffic. OLSR could rather be described as a route maintenance protocol in that it is responsible for maintaining the routing table used for routing packages, but such protocols are usually referred to as routing protocols.