What are some of the key terms associated with the Diffusing Update Algorithm (DUAL)?

Question

What will be an ideal response?

Answer 1

In order to understand DUAL, you must understand several key terms associated with it:
• Successor-The best route to a destination; the next hop route to a network; stored in the EIGRP topology table and placed as the best route in the actual routing table
• Feasible distance (FD)-The lowest metric to a destination (determines which route becomes the successor)
• Reported distance (RD)-The distance a router advertises to a network; in other words, the distance from an advertising router to a network
• Feasible successor-A backup route to the successor route; must meet the feasibility condition for DUAL; stored as a backup in the topology table; does not get placed in the routing table until the successor fails
• Feasibility condition-Used to ensure that a backup route (i.e., a feasible successor) does not contain a loop; to become a feasible successor, a router's RD must be less than its neighbor's FD. The easiest way to remember the feasibility condition is:
If RD < FD = feasible successor
• Adjacency-A relationship formed between EIGRP neighbors through the use of Hello packets