EIGRP is a proprietary distance vector routing protocol developed by Cisco that uses DUAL algorithm. It provides fast convergence using neighbor adjacencies, variable length subnet masking, and supports authentication using MD5. The metric formula takes bandwidth, delay, reliability, load, and MTU into consideration to determine the best path. EIGRP configuration allows tuning of K values, summarization, stub routing, authentication, and interface settings. Troubleshooting commands include show ip eigrp to view neighbor tables, topology, interfaces, and traffic as well as debug for packet tracing.