Background/Objective: Interior gateway protocols are used for communication between devices in an organizational network. The setup which includes routers, switches and hosts is simulated in GNS3 software to represent a complex real time enterprise level network. Each protocol is implemented in the designed topology. Methods/Statistical analysis: Interior gateway protocols-RIP (Routing Information Protocol), OSPF (Open Shortest Path First) and EIGRP (Enhanced Interior Gateway Routing Protocol) are analyzed in a complex enterprise level network using GNS3 software. Findings: Each protocol implemented in the designed topology is analyzed in terms of throughput, end to end delay and convergence time. Authentication is provided at each node so as to ensure secure transmission of data. The aim of the study is to find out the best feasible interior gateway routing protocol for different traffic scenarios. Application: The best interior gateway protocol can be found which can be used in an organizational network.