Find out which route in Fred's routing table comes from Wilma, Betty and Barney. Which router is the successor? Which router is the feasible successor? How many feasible successor does Fred have and why?

Additional data

Exercise is based on Figure 1-20, which is reproduced below

Fred#show ip eigrp topology 1.0.0.5 255.255.255.255
IP-EIGRP topology entry for 1.0.0.5/32
  State is Passive, Query origin flag is 1, 1 Successor(s), FD is 41152000
  Routing Descriptor Blocks:
  1.1.0.1 (Serial0), from 1.1.0.1, Send flag is 0x0
      Composite metric is (41152000/40640000), Route is Internal
      Vector metric:
        Minimum bandwidth is 64 Kbit
        Total delay is 45000 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 2
  1.1.0.3 (Serial0), from 1.1.0.3, Send flag is 0x0
      Composite metric is (46866176/46354176), Route is Internal
      Vector metric:
        Minimum bandwidth is 56 Kbit
        Total delay is 45000 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 2
  1.0.0.2 (Serial0.1), from 1.0.0.2, Send flag is 0x0
      Composite metric is (53973248/128256), Route is Internal
      Vector metric:
        Minimum bandwidth is 48 Kbit
        Total delay is 25000 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 1

Solution

To find out which router sent a specific entry in EIGRP topology table to Fred, refer to the "from" field in each entry (colored blue). The IP address in the "from" field is the adjacent router's interface address. To find out which IP address belongs to which router, examine Example 1-8, Example 1-10 and Example 1-13. The IP address of the adjacent router is shown in the debugging printout and the Example header tells you which router sent specific packets to Fred. Based on these examples, the interface IP addresses of Wilma, Betty and Barney are:

Router name	IP address
Barney	1.0.0.2
Betty	1.1.0.3
Wilma	1.1.0.1

The first entry in the topology database thus comes from Wilma, the second from Betty and the last one from Barney.

The topology database printout is always sorted by the router's own distance (colored brown in the printout). The first entry in the topology database always points toward the successor, in this case Wilma.

Feasible successors are all routers with reported distance (colored purple in the printout) smaller than the router's own distance (colored pink). Barney is therefore a feasible successor, but Betty is not. Fred has only one feasible successor.