EIGRP Distance vector or Link State?
A frequently asked question is whether EIGRP is distance vector or link-state protocol. EIGRP uses a hello protocol and �on demand� updates. This leads some people to believe that it falls into the category of link state. On the other hand EIGRP also uses aspects of the distance vector model such as relying on the neighbor�s perception of the network to calculate the best.
Cisco market EIGRP as a hybrid routing protocol. DUAL, which is the essence of the EIGRP decision process, was developed by JJ Garcia Luna�Alceves who describes DUAL as an advance distance vector algorithm in his original works, and verified in his original works, and verified this in a personal communication with Howard Berkowitz. Despite Cisco marketing of EIGRP as a hybrid routing protocol, it is in fact a distance vector protocol, albeit of an advance form.
