EIGRP負載均衡
EIGRP負載均衡
1.實驗目的
通過本實驗可以掌握：
（1）EIGRP等價負載均衡的實現方法
（2）EIGRP非等價負載均衡的實現方法
（3）EIGRP等價負載均衡的實現方法
（4）EIGRP非等價負載均衡的實現方法
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
實驗調試：
在R0上，關注12.1.1.0/24網絡，雖然路由器R0到達12.1.1.0/24網絡有兩條路徑，但是路由器會將FD最小的放入路由表，選擇走g0/0接口。那麼另外一條路徑是不是可行後繼路由呢？在路由器R0上查看拓撲表如下：
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
從上面的輸出中可以看到，第二條路徑（走s0/0接口）的AD爲2169856，而（successors）最優路由（走e1/0接口）的FD爲2195456，AD<FD,滿足可行性條件，所以第二條路徑（走s0/0 接口）是最優路由（走e1/0接口）的可行後繼。
當最優路徑down後，會啓動備份路由。如果沒有備份路由，路由器就以組播的方式向它的鄰居發送一個查詢包，以詢問它們是否有一條到目的地的後繼路由。
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(最優路徑) 和feasible successor（次優路徑）。
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
等價負載均衡（metric相等）：
上面輸出可以看出,到14.1.1.0/24網絡存在兩條successor，那麼這兩條路由都會放入路由表，
思考：等價負載均衡換成非等價負載均衡要怎麼做呢。
1. 不等價負載均衡： 必要條件 feasible successor：fs的AD<successor的FD （默認支持4條。
在路由模式下，maximum-path，能後variance
2.FS的FD<=Variance值*successor的FD（FS的metric <= 最優路由的metric × variance）， 就可以成爲非等價負載均衡路徑（不等價負載均衡前提條件：successor和feasible successor之間）。
操作如下：
1.把via 13.1.1.2 (2195456/281600), Serial0/1這條路徑改成feasible successor。
AD=281600< successors FD = 2195456
條件成立
2. feasible successor FD> successors FD
FD metric計算公式：
BW：路由路徑中的最小帶寬（單位k），DIY：路由路徑的各延遲之和（單位微妙usec）。
例如：via 13.1.1.2 (2195456/281600), Serial0/1
（路由流向的入接口延遲之和，以及帶寬的最小值。）
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.
延遲之和是1000加20000等於21000
帶入上面公式計算：
10^7除以1544等於6476.683937823834 （注意這裏就取整數） 6476
延遲之和除以10就是2100
6476加2100等於8576
8576乘以256等於2195456
所以，這樣我們可以改延遲和改大點，以達到（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
調試結果：
查看拓撲表信息：
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
從上面輸出可以明顯看出：FS的metric <= 最優路由的metric × variance（variance=2）
是成立的。接下來配置如下：
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
//最優路徑放入路由表。
配置後，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
//實現了不等價負載均衡