This paper presents a comprehensive study on the performance analysis of common MANET (Mobile Ad hoc NETwork) routing protocols under realistic network scenarios. Routing in ad-hoc networks is nontrivial due to highly dynamic environment. An ad hoc protocol can also mean an improvised and often impromptu protocol established for a particular specific purpose for these reasons several routing protocols targeted at mobile ad-hoc networks are being proposed. The routing protocols used in this paper include AODV, DSR, OLSR, DSDV, LAR and TORA, which comprise a good mix of reactive, proactive and hybrid protocols. This paper investigates and undertakes simulation based study of Mobile Ad-hoc NETwork (MANET) routing protocols. All protocols are provided with identical traffic load and mobility patterns.