The only change I did in the scenario is that I have added a direct link from R6 to R8.
Before adding this link the topology table in R6 was:
R6(config-if)#do sh ip eigrp top
IP-EIGRP Topology Table for AS(10)/ID(192.168.1.3)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P 192.168.1.0/24, 1 successors, FD is 281600
via Connected, Ethernet0/0
P 192.168.2.0/24, 3 successors, FD is 307200
via 192.168.1.1 (307200/281600), Ethernet0/0
via 192.168.1.2 (307200/281600), Ethernet0/0, serno 76
via 192.168.1.4 (307200/281600), Ethernet0/0, serno 57
P 192.168.3.0/24, 3 successors, FD is 332800
via 192.168.1.1 (332800/307200), Ethernet0/0
via 192.168.1.2 (332800/307200), Ethernet0/0, serno 77
via 192.168.1.4 (332800/307200), Ethernet0/0, serno 89
P 192.168.4.0/24, 3 successors, FD is 358400
via 192.168.1.1 (358400/332800), Ethernet0/0
via 192.168.1.2 (358400/332800), Ethernet0/0
via 192.168.1.4 (358400/332800), Ethernet0/0
P 192.168.5.0/24, 3 successors, FD is 486400
via 192.168.1.1 (486400/460800), Ethernet0/0
via 192.168.1.2 (486400/460800), Ethernet0/0
via 192.168.1.4 (486400/460800), Ethernet0/0
P 192.168.6.0/24, 3 successors, FD is 486400
via 192.168.1.1 (486400/460800), Ethernet0/0
via 192.168.1.2 (486400/460800), Ethernet0/0
via 192.168.1.4 (486400/460800), Ethernet0/0
P 192.168.7.0/24, 3 successors, FD is 384000
via 192.168.1.1 (384000/358400), Ethernet0/0
via 192.168.1.2 (384000/358400), Ethernet0/0
via 192.168.1.4 (384000/358400), Ethernet0/0
AFTER ADDING THE LINK
R6(config-if)#do sh ip eigrp top
IP-EIGRP Topology Table for AS(10)/ID(192.168.1.3)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P 192.168.1.0/24, 1 successors, FD is 281600
via Connected, Ethernet0/0
P 192.168.2.0/24, 3 successors, FD is 307200
via 192.168.1.1 (307200/281600), Ethernet0/0
via 192.168.1.2 (307200/281600), Ethernet0/0, serno 76
via 192.168.1.4 (307200/281600), Ethernet0/0, serno 57
P 192.168.3.0/24, 4 successors, FD is 332800
via 192.168.1.1 (332800/307200), Ethernet0/0
via 192.168.1.2 (332800/307200), Ethernet0/0, serno 77
via 192.168.1.4 (332800/307200), Ethernet0/0, serno 89
via 192.168.7.2 (332800/307200), Ethernet0/1
P 192.168.4.0/24, 1 successors, FD is 307200
via 192.168.7.2 (307200/281600), Ethernet0/1
P 192.168.5.0/24, 1 successors, FD is 409600
via 192.168.7.2 (409600/128256), Ethernet0/1
P 192.168.6.0/24, 1 successors, FD is 409600
via 192.168.7.2 (409600/128256), Ethernet0/1
P 192.168.7.0/24, 1 successors, FD is 281600
via Connected, Ethernet0/1
why??
1 comment:
this example will successfully explain when a feasible successor route will be introduced in
show ip route:
|---5-----R2--10--R3--10--|
R1- -switch---->R5----n/w
|----5-----R4----10----------|
Route 1> R1-->R4--->R5-->n/w
FD=5+10+5=20
AD=10+5=15
Route 2> R1-->R2-->R3-->R5-->n/w
FD=5+10+10+5=30
AD=10+10+5=25
Cost of Route 1 < Route 2 Hence Route 1 will be successor. Now we know that to qualify a route as a Feasible successor we need to have the AD of a feasible successor should be less than FD of a successor
so we need to compare the Route 2 AD and Route 1 FD. But we found that 25 is not less than 20. Hence there will be no feasible successor.
Hope this helps
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