Information Technology Reference
In-Depth Information
Notice that the reported distance of the feasible successor is less than the feasible distance of the successor.
For route 10.10.14.128/25 . . .
What is the IP address of the successor?
172.16.1.38
What is the reported distance of the successor?
2172416
What is the feasible distance of the successor?
6026496
What is the IP address of the feasible successor?
172.16.1.42
What is the reported distance of the feasible successor?
28160
What is the feasible distance of the feasible successor?
7181056
Notice that the reported distance of the feasible successor is less than the feasible distance of the suc-
cessor.
What happens if an EIGRP router doesn't have a feasible successor in the topology table and the
router loses connection to the successor?
DUAL must be recomputed and neighbors queried for a possible backup route.
DUAL FSM Completion Exercise
A Finite State Machine (FSM) is an abstract machine, not a mechanical device with moving parts.
FSMs define a set of possible states that something can go through, what events cause those states,
and what events result from those states. Designers use FSMs to describe how a device, computer pro-
gram, or routing algorithm will react to a set of input events.
Figure 9-7 is a simplified flow chart of DUAL's FSM. Fill in the flow chart with the states EIGRP
moves through when it loses connectivity with a successor. The flow chart should serve as a visual
study aid to help you remember how DUAL converges on new routes.
