3.5.f unequal-cost (EIGRP)

note: the bandwidth of the interfaces have been artificially adjusted for illustration


r1#sh ip proto
Routing Protocol is “eigrp 123”
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Default networks flagged in outgoing updates
Default networks accepted from incoming updates
EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0
EIGRP maximum hopcount 100
EIGRP maximum metric variance 1
Redistributing: eigrp 123
EIGRP NSF-aware route hold timer is 240s
Automatic network summarization is not in effect
Maximum path: 4
Routing for Networks:
Routing Information Sources:
Gateway         Distance      Last Update
(this router)         90      00:34:41           90      00:01:20           90      00:01:20           90      00:01:20
Distance: internal 90 external 170

r1#sh ip eigrp topo
IP-EIGRP Topology Table for AS(123)/ID(

Codes: P – Passive, A – Active, U – Update, Q – Query, R – Reply,
r – reply Status, s – sia Status

P, 1 successors, FD is 128256
via Connected, Loopback0
P, 1 successors, FD is 3142400
via (3142400/156160), Serial0/0
via (5642496/156160), Serial0/1
via (20642560/156160), Serial0/2

the feasible distance is established at 3142400, hence s0/0 is the successor route.  for s0/1 the feasible distance is nearly twice that of s0/0.

since the default variance is 1, the ip routing table will only display the successor.

if the variance is doubled (2 X 3142400) the ip routing table will now recognize near equal cost routes:

r1(config-router)#do sh run | b router
router eigrp 123
variance 2
no auto-summary

r1(config-router)#do sh ip route | b Gate
Gateway of last resort is not set is subnetted, 1 subnets
C is directly connected, Loopback0 is subnetted, 1 subnets
D [90/5642496] via, 00:01:06, Serial0/1
                [90/3142400] via, 00:01:06, Serial0/0