uses the same distance vector algorithm and distance information as IGRP. However,
the convergence properties and the operating efficiency of enhanced IGRP have
The convergence technology is based on research conducted at SRI International
and employs an algorithm referred to as the Diffusing Update Algorithm (DUAL).
This algorithm guarantees loop-free operation at every instant throughout a route
computation and allows all routers involved in a topology change to synchronize
at the same time. Routers that are not affected by topology changes are not involved
convergence time with DUAL rivals that of any other existing routing protocol.
The initial implementation of IGRP operated in Internet Protocol (IP) networks.
Enhanced IGRP extends IGRP so that it is independent of the network-layer protocol.
In addition to IP, it now also operates in AppleTalk and Novell IPX networks.
Gateway Routing Protocol, Cisco Systems, 1987.