In Mobile Ad hoc Network (MANET), mobility, traffic and node density are main network conditions that significantly affect the performance of routing protocols. Much of the previous researches in MANET routing have focused on developing strategies, which suit one specific networking scenario. Therefore, there is no existing protocol that can work well in all different networking scenarios. This paper reviews characteristics of each different classes of routing protocols. Moreover, most of current routing protocols assume homogeneous networking conditions where all nodes have the same capabilities and resources. Although homogenous networks are easy to model and analysis, they exhibits poor scalability compared with heterogeneous networks that consist of different nodes with different resources. This paper presents extensive studies simulations for DSR, AODV, LAR1, FSR and WRP in homogenous and heterogeneous networks. The results showed that these which all protocols perform reasonably well in homogenous networking conditions, their performance suffer significantly over heterogonous networks.