A new type of network is coming into use, Mobile ad-hoc Networks (MANETs), these networks are dynamically constructed out of wireless nodes. Designing routing protocols for these networks presents several challenges and issues such as scalability and stability which must be solved. Software simulators which can simulate both wired and wireless networks are very useful when designing routing protocols for use in MANETs. They allow specific problems to be isolated and recreated in order to study and find solutions for them. J-Sim is one such software simulator. J-Sim is written in the Java programming language which makes it highly portable across different hardware platforms. This thesis presents the work on implementing the Optimized Link State Routing protocol (OLSR) for J-Sim.