Enhanced Interior Gateway Routing Protocol (EIGRP) is a routing protocol created by Cisco and is based on the concept of Interior Gateway Protocol (IGRP). It is a sophisticated distance vector routing protocol that includes optimizations to reduce routing instability due to topology changes, bandwidth usage, and processing power. EIGRP collects information and stores in 3 tables. It also does not rely on periodic route dumps. EIGRP was designed for Cisco devices initially, however in 2013, EIGRP was made open standard. EIGRP has a max hop count of 255 and default of 100 and has a Hello timer of 5 seconds and a dead time of 15 seconds.
Some potential issues that can arise with EIGRP are local EIGRP routers not establishing EIGRP neighbors with neighboring routers, which an EIGRP Neighbor Check would help fix, routes whether static or dynamic might not be distributed into EIGRP- an EIGRP Redistribution Check would help. Routes could also be missing from the routing table and would need an EIGRP Route Check. EIGRP seeing routes could also be Stuck In Active (SIA).
“Troubleshooting EIGRP.” Cisco. www.Cisco.com. Web. 21 July 2008. Retrieved 8 Aug 2017.