diffusing update algorithm
Abbreviated as DUAL, the diffusing update algorithm is a routing protocol used by EIGRP to calculate and create routing tables to determine whether a path is looped or loop-free. It also allows a router running EIGRP to find alternate paths without waiting on updates from other routers. The diffusing update algorithm (DUAL) was developed at SRI International by Dr. J.J. Garcia-Luna-Aceves.
See also Enhanced Interior Gateway Routing Protocol (EIGRP).