EIGRP浮动汇总路由配置过程如下：
EIGRP浮动汇总路由配置之拓扑图
EIGRP浮动汇总路由配置之接口连接
- Router1 S0/0 <----> Router2 S0/0
- Router2 S0/1 <----> Router3 S0/0
- Router1 S0/1 <----> Router4 S0/0
- Router3 S0/1 <----> Router4 S0/1
- VPCS V0/1 <----> Router1 E1/0
- VPCS V0/2 <----> Router3 E1/0
EIGRP浮动汇总路由配置之原理
在R1\R2\R3\R4上均运行EIGRP路由协议。R4通过S0/1向R3通告一条0.0.0.0 0.0.0.0的汇总路由，并将这条浮动路由的管理距离设置为250，于是在网络连通的情况下R3上到达200.1.1.0/24网段的路由经过R2，而在R2与R3链路故障的时候，通过R3前往200.1.1.0/24的数据包会通过R4（R3拓扑表中，默认路由由A变为P）
EIGRP浮动汇总路由配置之关键配置
- R1:
- interface Serial0/0
- ip address 192.168.1.1 255.255.255.0
- serial restart-delay 0
- !
- interface Serial0/1
- ip address 192.168.3.1 255.255.255.0
- serial restart-delay 0
- !
- interface Ethernet1/0
- ip address 200.1.1.254 255.255.255.0
- half-duplex
- !
- router eigrp 100
- network 192.168.1.0
- network 192.168.3.0
- network 200.1.1.0
- no auto-summary
R2、R3略，参照R1进行接口IP和路由协议的配置，重点看下R4的配置
- R4:
- interface Serial0/0
- ip address 192.168.3.2 255.255.255.0
- serial restart-delay 0
- !
- interface Serial0/1
- ip address 192.168.4.1 255.255.255.0
- ip summary-address eigrp 100 0.0.0.0 0.0.0.0 250（向R3通过默认路由，管理距离高于EIGRP默认值）!
- router eigrp 100
- network 192.168.3.0
- network 192.168.4.0
- auto-summary
#p#
EIGRP浮动汇总路由配置之查看结果
1.R2和R3之间链路正常时
a) R3的路由表：
- R3#sh ip route
- Codes: C - connected, S - static, I - IGRP, 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, E - EGP
- 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 192.168.4.1 to network 0.0.0.0
- D 200.1.1.0/24 [90/2707456] via 192.168.2.1, 00:00:02, Serial0/0
- C 200.1.2.0/24 is directly connected, Ethernet1/0
- C 192.168.4.0/24 is directly connected, Serial0/1
- D 192.168.1.0/24 [90/2681856] via 192.168.2.1, 00:00:02, Serial0/0
- C 192.168.2.0/24 is directly connected, Serial0/0
- D 192.168.3.0/24 [90/3193856] via 192.168.2.1, 00:00:02, Serial0/0
- D* 0.0.0.0/0 [90/2681856] via 192.168.4.1, 00:00:00, Serial0/1
b)R3的拓扑表：
- R3#sh ip eigrp topology
- IP-EIGRP Topology Table for AS(100)/ID(200.1.2.254)
- Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
- r - reply Status, s - sia Status
- A 0.0.0.0/0, 1 successors, FD is Inaccessible
- 1 replies, active 00:00:00, query-origin: Successor Origin
- Remaining replies:
- via 192.168.2.1, r, Serial0/0
- P 192.168.1.0/24, 1 successors, FD is 2681856
- via 192.168.2.1 (2681856/2169856), Serial0/0
- P 192.168.2.0/24, 1 successors, FD is 2169856
- via Connected, Serial0/0
- P 192.168.3.0/24, 1 successors, FD is 3193856
- via 192.168.2.1 (3193856/2681856), Serial0/0
- P 192.168.4.0/24, 1 successors, FD is 2169856
- via Connected, Serial0/1
- P 200.1.1.0/24, 1 successors, FD is 2707456
- via 192.168.2.1 (2707456/2195456), Serial0/0
- P 200.1.2.0/24, 1 successors, FD is 281600
- via Connected, Ethernet1/0
2.R2的S0/1设置为DOWN,观察R3路由表和拓扑表
a)R3路由表：
- R3#sh ip route
- Codes: C - connected, S - static, I - IGRP, 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, E - EGP
- 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 192.168.4.1 to network 0.0.0.0
- C 200.1.2.0/24 is directly connected, Ethernet1/0
- C 192.168.4.0/24 is directly connected, Serial0/1
- C 192.168.2.0/24 is directly connected, Serial0/0
- D* 0.0.0.0/0 [90/2681856] via 192.168.4.1, 00:00:05, Serial0/1
b)R3的拓扑表：
- R3#sh ip eigrp topology
- IP-EIGRP Topology Table for AS(100)/ID(200.1.2.254)
- Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
- r - reply Status, s - sia Status
- P 0.0.0.0/0, 1 successors, FD is 2681856
- via 192.168.4.1 (2681856/2169856), Serial0/1
- P 192.168.4.0/24, 1 successors, FD is 2169856
- via Connected, Serial0/1
- P 200.1.2.0/24, 1 successors, FD is 281600
- via Connected, Ethernet1/0
EIGRP浮动汇总路由配置说明，当R2和R3链路正常是，通过R3去往PC1的数据包不通过R4，只有当R2、R3间链路出现故障，默认路由才启用。
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