Configuring EIGRP Unequal-Cost Paths
1、配置各台路由器的IP地址，并且使用Ping命令确认各路由器的直连口的互通性。
2、在三台路由配置EIGRP自治系统编号为100。
R1(config-if)#int lo0
R1(config-if)#ip add 1.1.1.1 255.255.255.0
R1(config)#int e1/0
R1(config-if)#ip add 10.2.2.1 255.255.255.0
R1(config-if)#no shut
R1(config-if)#int s2/0
R1(config-if)#ip add 10.1.1.1 255.255.255.0
R1(config-if)#clo r 64000
R1(config-if)#no shut
R1(config)#router e 100
R1(config-router)#net 1.1.1.0
R1(config-router)#net 10.1.1.0
R1(config-router)#net 10.2.2.0
R1(config-router)#no au
R2(config)#int s1/0
R2(config-if)#ip add 10.1.1.2 255.255.255.0
R2(config-if)#no shut
R2(config-if)#int s1/1
R2(config-if)#ip add 10.3.3.1 255.255.255.0
R2(config-if)#clo r 64000
R2(config-if)#no shut
R2(config)#router e 100
R2(config-router)#net 10.1.1.0
R2(config-router)#net 10.3.3.0
R2(config-router)#no au
R3(config)#int lo0
R3(config-if)#ip add 3.3
R3(config-if)#ip add 3.3.3.3 255.255.255.0
R3(config-if)#int e1/0
R3(config-if)#ip add 10.2.2.2 255.255.255.0
R3(config-if)#no shut
R3(config-if)#int s2/0
R3(config-if)#ip add 10.3.3.2 255.255.255.0
R3(config-if)#no shut
R3(config)#router e 100
R3(config-router)#net 3.3.3.0
R3(config-router)#net 10.2.2.0
R3(config-router)#net 10.3.3.0
R3(config-router)#no au
3、观察R1到达R3的3.3.3.0/24网络的路由。
R1#sh ip route
1.0.0.0/24 is subnetted, 1 subnets
C
1.1.1.0 is directly connected, Loopback0
3.0.0.0/24 is subnetted, 1 subnets
D
3.3.3.0 [90/409600] via 10.2.2.2, 00:00:56, Ethernet1/0【到达3.3.3.0的网络的下一跳为10.2.2.2】
10.0.0.0/24 is subnetted, 3 subnets
D
10.3.3.0 [90/2195456] via 10.2.2.2, 00:02:21, Ethernet1/0
C
10.2.2.0 is directly connected, Ethernet1/0
C
10.1.1.0 is directly connected, Serial2/0
4、为了提高网络传输性能，需要同时使用下一跳为10.1.1.2的路由，即使用另外一条metric值不相等的路径做均衡负载。
5、如果需要使用另外一条路径，则需要确保R2成为R1到达3.3.3.0/24网络的可行后继(FS)，要想成为FS，则需要满足可行条件(FC)。【AD<FD】
6、在R1上查看EIGRP的拓扑表，没有发现R2出现在R1的拓扑表中。
R1#sh ip ei 100 topology
IP-EIGRP Topology Table for AS(100)/ID(1.1.1.1)
P 1.1.1.0/24, 1 successors, FD is 128256
via Connected, Loopback0
P 3.3.3.0/24, 1 successors, FD is 409600
via 10.2.2.2 (409600/128256), Ethernet1/0
【此处，没有出现R2的ip，说明R2不是R1到达3.3.3.0/24的可行后继。】
P 10.3.3.0/24, 1 successors, FD is 2195456
via 10.2.2.2 (2195456/2169856), Ethernet1/0
via 10.1.1.2 (2681856/2169856), Serial2/0
P 10.1.1.0/24, 1 successors, FD is 2169856
via Connected, Serial2/0
P 10.2.2.0/24, 1 successors, FD is 281600
via Connected, Ethernet1/0
7、查看完整的拓扑表内容。
R1#sh ip eigrp 100 topology all-links
IP-EIGRP Topology Table for AS(100)/ID(1.1.1.1)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P 1.1.1.0/24, 1 successors, FD is 128256, serno 1
via Connected, Loopback0
P 3.3.3.0/24, 1 successors, FD is 409600, serno 8
via 10.2.2.2 (
409600/128256
), Ethernet1/0
via 10.1.1.2 (
2809856/2297856
), Serial2/0
【AD<FD不满足】注（AD/FD）
P 10.3.3.0/24, 1 successors, FD is 2195456, serno 7
via 10.2.2.2 (2195456/2169856), Ethernet1/0
via 10.1.1.2 (2681856/2169856), Serial2/0
P 10.1.1.0/24, 1 successors, FD is 2169856, serno 3
via Connected, Serial2/0
P 10.2.2.0/24, 1 successors, FD is 281600, serno 2
via Connected, Ethernet1/0
8、确认FC(可行条件)公式：
AD of secondary-best route < FD of best route(Successor) = Feasible Successor
根据本例可得出：
R2到达3.3.3.0网络的Distance <409600
9、配置R2的EIGRP的度量，确保R2成为R1的可行后继者。
R2(config)#int s1/0
R2(config-if)#bandwidth 10000
【通过修改
R2到达R3的串口的带宽和延迟，确保R2到达3.3.3.0/24的网络的FD变小。此值在r1上显示为AD。】
R2(config-if)#delay 10
R2(config-if)#int s1/1
R2(config-if)#bandwidth 10000
R2(config-if)#delay 10
10、查看R1的拓扑表。
R1#sh ip eigrp 100 topology all-links
IP-EIGRP Topology Table for AS(100)/ID(1.1.1.1)
P 1.1.1.0/24, 1 successors, FD is 128256, serno 1
via Connected, Loopback0
P 3.3.3.0/24, 1 successors, FD is 409600, serno 8
via 10.2.2.2 (409600/128256), Ethernet1/0
via 10.1.1.2 (2300416/386560), Serial2/0
P 10.3.3.0/24, 1 successors, FD is 2172416, serno 9
via 10.1.1.2 (2172416/258560), Serial2/0
via 10.2.2.2 (2195456/2169856), Ethernet1/0
P 10.1.1.0/24, 1 successors, FD is 2169856, serno 3
via Connected, Serial2/0
via 10.2.2.2 (2198016/2172416), Ethernet1/0
P 10.2.2.0/24, 1 successors, FD is 281600, serno 2
via Connected, Ethernet1/0
11、根据如下公式配置R1的EIGRP的variance值。
FD of FS route < FD of best route(Successor) * Varince
根据公式可得出：
2300416 < 409600 * x
x≈5.61625
12、为了测试，先在R1上配置variance值为5，观察路由表。
R1(config)#
router eigrp 100
R1(config-router)#
variance 5
R1(config-router)#
exit
R1(config)#
exit
R1#
clear ip router *
R1#sh ip route
1.0.0.0/24 is subnetted, 1 subnets
C
1.1.1.0 is directly connected, Loopback0
3.0.0.0/24 is subnetted, 1 subnets
D
3.3.3.0 [90/409600] via 10.2.2.2, 00:00:03, Ethernet1/0
【设置为
5时，不能满足不等价的条件。】
10.0.0.0/24 is subnetted, 3 subnets
D
10.3.3.0 [90/2195456] via 10.2.2.2, 00:00:03, Ethernet1/0
[90/2172416] via 10.1.1.2, 00:00:03, Serial2/0
C
10.2.2.0 is directly connected, Ethernet1/0
C
10.1.1.0 is directly connected, Serial2/0
13、将R1的variance值修改为6后，观察路由表。
R1(config)#
router eigrp 100
R1(config-router)#
variance 6
R1(config-router)#
exit
R1(config)#
exit
R1#
clear ip router *
R1#sh ip route
Codes: C - connected, D - EIGRP
1.0.0.0/24 is subnetted, 1 subnets
C 1.1.1.0 is directly connected, Loopback0
3.0.0.0/24 is subnetted, 1 subnets
D 3.3.3.0 [90/409600] via 10.2.2.2, 00:00:05, Ethernet1/0
[90/2300416] via 10.1.1.2, 00:00:05, Serial2/0
【设置正确的
variance值后，此处显示为正确的不等价均衡负载的路由。
】
10.0.0.0/24 is subnetted, 3 subnets
D 10.3.3.0 [90/2195456] via 10.2.2.2, 00:00:05, Ethernet1/0
[90/2172416] via 10.1.1.2, 00:00:05, Serial2/0
C 10.2.2.0 is directly connected, Ethernet1/0
C 10.1.1.0 is directly connected, Serial2/0