IGP-LAB-EIGRP负载均衡（详解）
EIGRP负载均衡
EIGRP负载均衡
1.实验目的
通过本实验可以掌握：
（
1）EIGRP等价负载均衡的实现方法
（
2）EIGRP非等价负载均衡的实现方法
（
3）EIGRP等价负载均衡的实现方法
（
4）EIGRP非等价负载均衡的实现方法
R0:
R0(config)#int e1/0
R0(config-if)#ip add 14.1.1.2 255.255.255.0
R0(config-if)#no sh
R0(config-if)#int lo0
R0(config-if)#ip add 1.1.1.1 255.255.255.0
R0(config-if)#no sh
R0(config-if)#int s0/0
R0(config-if)#ip add 13.1.1.2 255.255.255.0
R0(config-if)#clo r 64000
R0(config-if)#no sh
R0(config-if)#exit
R0(config)#router eig 110
R0(config-router)#no auto-summary
R0(config-router)#network 1.1.1.0 0.0.0.255
R0(config-router)#network 13.1.1.0 0.0.0.255
R0(config-router)#network 14.1.1.0 0.0.0.255
R1:
R1(config)#int e1/0
R1(config-if)#ip add 14.1.1.1 255.255.255.0
R1(config-if)#no sh
R1(config-if)#int s0/1
R1(config-if)#ip add 12.1.1.1 255.255.255.0
R1(config-if)#clo r 64000
R1(config-if)#no sh
R1(config-if)#int lo0
R1(config-if)#ip add 2.2.2.2 255.255.255.0
R1(config-if)#no sh
R0(config-if)#exit
R1(config)#router eig 110
R1(config-router)#no auto-summary
R1(config-router)#network 12.1.1.0 0.0.0.255
R1(config-router)#network 2.2.2.0 0.0.0.255
R1(config-router)#network 14.1.1.0 0.0.0.255
R2:
R2(config)#int s0/2
R2(config-if)#ip add 12.1.1.2 255.255.255.0
R2(config-if)#clo r 64000
R2(config-if)#no sh
R2(config-if)#int lo0
R2(config-if)#ip add 3.3.3.3 255.255.255.0
R2(config-if)#no sh
R2(config-if)#int s0/1
R2(config-if)#ip add 13.1.1.1 255.255.255.0
R2(config-if)#clo r 64000
R2(config-if)#no sh
R0(config-if)#exit
R2(config)#router eig 110
R2(config-router)#no auto-summary
R2(config-router)#network 12.1.1.0 0.0.0.255
R2(config-router)#network 3.3.3.0 0.0.0.255
R2(config-router)#network 13.1.1.0 0.0.0.255
实验调试：
在R0上，关注
12.1.1.0/24网络，虽然路由器R0到达12.1.1.0/24网络有两条路径，但是路由器会将
FD最小的放入路由表，选择走g0/0接口。那么另外一条路径是不是可行后继路由呢？在路由器R0上查看拓扑表如下：
R0#sh ip eigrp topology
IP-EIGRP Topology Table for AS(110)/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
via Connected, Loopback0
P 2.2.2.0/24, 1 successors, FD is 409600
via 14.1.1.1 (409600/128256), Ethernet1/0
P 3.3.3.0/24, 1 successors, FD is 2297856
via 13.1.1.1 (2297856/128256), Serial0/0
P 12.1.1.0/24, 1 successors, FD is 2195456
via 14.1.1.1 (2195456/2169856), Ethernet1/0
via 13.1.1.1 (2681856/2169856), Serial0/0
P 13.1.1.0/24, 1 successors, FD is 2169856
via Connected, Serial0/0
P 14.1.1.0/24, 1 successors, FD is 281600
via Connected, Ethernet1/0
从上面的输出中可以看到，第二条路径（走s0/0接口）的AD为2169856，而（successors）最优路由（走e1/0接口）的FD为2195456，AD<FD,满足可行性条件，所以第二条路径（走s0/0 接口）是最优路由（走e1/0接口）的可行后继。
当最优路径down后，会启动备份路由。如果没有备份路由，路由器就以组播的方式向它的邻居发送一个查询包，以询问它们是否有一条到目的地的后继路由。
R1#sh ip eigrp topology
IP-EIGRP Topology Table for AS(110)/ID(2.2.2.2)
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 409600
via 14.1.1.2 (409600/128256), Ethernet1/0
P 2.2.2.0/24, 1 successors, FD is 128256
via Connected, Loopback0
P 3.3.3.0/24, 1 successors, FD is 2297856
via 12.1.1.2 (2297856/128256), Serial0/1
P 12.1.1.0/24, 1 successors, FD is 2169856
via Connected, Serial0/1
P 13.1.1.0/24, 1 successors, FD is 2195456
via 14.1.1.2 (2195456/2169856), Ethernet1/0
via 12.1.1.2 (2681856/2169856), Serial0/1
P 14.1.1.0/24, 1 successors, FD is 281600
via Connected, Ethernet1/0
同理：在R1
上也存在successor(
最优路径)
和feasible successor
（次优路径）。
再看看R2
上：
R2#sh ip eigrp to
IP-EIGRP Topology Table for AS(110)/ID(3.3.3.3)
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 2297856
via 13.1.1.2 (2297856/128256), Serial0/1
via 12.1.1.1 (2323456/409600), Serial0/2
P 2.2.2.0/24, 1 successors, FD is 2297856
via 12.1.1.1 (2297856/128256), Serial0/2
via 13.1.1.2 (2323456/409600), Serial0/1
P 3.3.3.0/24, 1 successors, FD is 128256
via Connected, Loopback0
P 12.1.1.0/24, 1 successors, FD is 2169856
via Connected, Serial0/2
P 13.1.1.0/24, 1 successors, FD is 2169856
via Connected, Serial0/1
P 14.1.1.0/24, 2 successors, FD is 2195456
via 12.1.1.1 (2195456/281600), Serial0/2
via 13.1.1.2 (2195456/281600), Serial0/1
等价负载均衡（metric相等）：
上面输出可以看出,到14.1.1.0/24网络存在两条successor，那么这两条路由都会放入路由表，
思考：等价负载均衡换成非等价负载均衡要怎么做呢。
1. 不等价负载均衡： 必要条件 feasible successor：fs的AD<successor的FD （默认支持4条。
在路由模式下，maximum-path，能后variance
2.FS的FD<=Variance值*successor的FD（FS的metric <= 最优路由的metric × variance）， 就可以成为非等价负载均衡路径（不等价负载均衡前提条件：successor和feasible successor之间）。
操作如下：
1.
把via 13.1.1.2 (2195456/281600), Serial0/1
这条路径改成feasible successor
。
AD=281600< successors FD = 2195456
条件成立
2.
feasible successor FD> successors FD
FD metric计算公式：
BW
：路由路径中的最小带宽（单位k
），DIY
：路由路径的各延迟之和（单位微妙usec
）。
例如：via 13.1.1.2 (2195456/281600), Serial0/1
（路由流向的入接口延迟之和，以及带宽的最小值。）
BW
：
A.
R0
的e1/0
接口：
R0#sh int e1/0
Ethernet1/0 is up, line protocol is up
Hardware is AmdP2, address is cc00.1644.0010 (bia cc00.1644.0010)
Internet address is 14.1.1.2/24
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
B
． R2
的S0/1
接口
R2#sh int s0/1
Serial0/1 is up, line protocol is up
Hardware is M4T
Internet address is 13.1.1.1/24
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
BW
最小值是1544.
延迟之和是1000
加20000
等于21000
带入上面公式计算：
10^7
除以1544
等于6476.683937823834
（注意这里就取整数） 6476
延迟之和除以10
就是2100
6476
加2100
等于8576
8576
乘以256
等于2195456
所以，这样我们可以改延迟和改大点，以达到（feasible successor FD> successors FD
）目的。
操作如下：
R0(config)#int e1/0
R0(config-if)#delay 1500
R0(config-if)#end
R0#sh int e1/0
Ethernet1/0 is up, line protocol is up
Hardware is AmdP2, address is cc00.1644.0010 (bia cc00.1644.0010)
Internet address is 14.1.1.2/24
MTU 1500 bytes,
BW 10000 Kbit, DLY 15000 usec
调试结果：
查看拓扑表信息：
R2#sh ip eigrp to
IP-EIGRP Topology Table for AS(110)/ID(3.3.3.3)
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 2297856
via 13.1.1.2 (2297856/128256), Serial0/1
via 12.1.1.1 (2323456/409600), Serial0/2
P 2.2.2.0/24, 1 successors, FD is 2297856
via 12.1.1.1 (2297856/128256), Serial0/2
via 13.1.1.2 (2681856/768000), Serial0/1
P 3.3.3.0/24, 1 successors, FD is 128256
via Connected, Loopback0
P 12.1.1.0/24, 1 successors, FD is 2169856
via Connected, Serial0/2
P 13.1.1.0/24, 1 successors, FD is 2169856
via Connected, Serial0/1
P 14.1.1.0/24, 1 successors, FD is 2195456
via 12.1.1.1 (2195456/281600), Serial0/2
via 13.1.1.2 (2553856/640000), Serial0/1
从上面输出可以明显看出：FS的metric <= 最优路由的metric × variance（variance=2）
是成立的。接下来配置如下：
查看R2
路由表：R2#sh ip ro
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
1.0.0.0/24 is subnetted, 1 subnets
D 1.1.1.0 [90/2297856] via 13.1.1.2, 00:27:19, Serial0/1
2.0.0.0/24 is subnetted, 1 subnets
D 2.2.2.0 [90/2297856] via 12.1.1.1, 00:07:28, Serial0/2
3.0.0.0/24 is subnetted, 1 subnets
C 3.3.3.0 is directly connected, Loopback0
12.0.0.0/24 is subnetted, 1 subnets
C 12.1.1.0 is directly connected, Serial0/2
13.0.0.0/24 is subnetted, 1 subnets
C 13.1.1.0 is directly connected, Serial0/1
14.0.0.0/24 is subnetted, 1 subnets
D 14.1.1.0 [90/2195456] via 12.1.1.1, 00:07:38, Serial0/2
//最优路径放入路由表。
配置后，查看R2路由表：
R2(config)#router eig 110
R2(config-router)#variance 2
R2#sh ip ro
*Mar 1 00:28:20.763: %SYS-5-CONFIG_I: Configured from console by console
R2#sh ip ro
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
1.0.0.0/24 is subnetted, 1 subnets
D 1.1.1.0 [90/2297856] via 13.1.1.2, 00:00:03, Serial0/1
[90/2323456] via 12.1.1.1, 00:00:03, Serial0/2
2.0.0.0/24 is subnetted, 1 subnets
D 2.2.2.0 [90/2681856] via 13.1.1.2, 00:00:03, Serial0/1
[90/2297856] via 12.1.1.1, 00:00:03, Serial0/2
3.0.0.0/24 is subnetted, 1 subnets
C 3.3.3.0 is directly connected, Loopback0
12.0.0.0/24 is subnetted, 1 subnets
C 12.1.1.0 is directly connected, Serial0/2
13.0.0.0/24 is subnetted, 1 subnets
C 13.1.1.0 is directly connected, Serial0/1
14.0.0.0/24 is subnetted, 1 subnets
D 14.1.1.0 [90/2553856] via 13.1.1.2, 00:00:04, Serial0/1
[90/2195456] via 12.1.1.1, 00:00:04, Serial0/2
//实现了不等价负载均衡
本文出自 “谢枫” 博客，转载请与作者联系！