Enhanced Interior Gateway Routing Protocol (EIGRP) Distance vector. Classless routing protocol. Released in 1992 with Cisco IOS Software Release . Enhancement of Cisco Interior Gateway Routing Protocol (IGRP). Both are Cisco proprietary. Operate only on Cisco term hybrid routing protocol is sometimes used to define EIGRP. Misleading, not a hybrid between distance vector and link-state Solely a distance vector routing protocol.