Manually Summarizing EIGRP Routes

实验目的：
1、理解EIGRP 的自动汇总的缺点。
2、掌握EIGRP 的手工自动总结的配置方法。
实验拓扑图：
16

实验步骤及要求：
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、配置各台路由器的EIGRP 协议,并且不关闭自动总结。
3、在R2 上使用ping 测试网络路由，会发现R2 路由器无法ping 通路由器R4
所连接的10.1.X.0/24 网络子网。如下所示：
R2#ping 10.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/46/92 ms
R2#
R2#ping 10.1.16.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.16.1, timeout is 2 seconds:
U.U.U
Success rate is 0 percent (0/5)
R2#
R2#ping 10.1.17.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.17.1, timeout is 2 seconds:
U.U.U
Success rate is 0 percent (0/5)
R2#
4、查看R2 的路由表：
R2#show ip route
Gateway of last resort is not set
172.16.0.0/30 is subnetted, 3 subnets
D 172.16.1.8 [90/307200] via 172.16.1.6, 00:06:25, Ethernet1/1
C 172.16.1.4 is directly connected, Ethernet1/1
C 172.16.1.0 is directly connected, Ethernet1/0
D 10.0.0.0/8 [90/409600] via 172.16.1.1, 00:06:09, Ethernet1/0
D 192.168.0.0/24 [90/409600] via 172.16.1.6, 00:06:25, Ethernet1/1
D 192.168.1.0/24 [90/409600] via 172.16.1.6, 00:06:25, Ethernet1/1
D 192.168.2.0/24 [90/409600] via 172.16.1.6, 00:06:25, Ethernet1/1
批注 [stanley22]: 无法
ping 通10.1.16.1 的IP 地
址。
批注 [stanley23]: R2 路由
器显示的汇总路由。
17
D 192.168.3.0/24 [90/409600] via 172.16.1.6, 00:06:25, Ethernet1/1
R2#
5、查看R2 路由器的拓扑数据库：
R2#show ip eigrp topology all-links
IP-EIGRP Topology Table for AS(50)/ID(172.16.1.5)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - Reply status
P 10.0.0.0/8, 1 successors, FD is 409600, serno 3
via 172.16.1.1 (409600/128256), Ethernet1/0
via 172.16.1.6 (435200/409600), Ethernet1/1
P 192.168.0.0/24, 1 successors, FD is 409600, serno 4
via 172.16.1.6 (409600/128256), Ethernet1/1
P 192.168.1.0/24, 1 successors, FD is 409600, serno 5
via 172.16.1.6 (409600/128256), Ethernet1/1
P 192.168.2.0/24, 1 successors, FD is 409600, serno 6
via 172.16.1.6 (409600/128256), Ethernet1/1
P 192.168.3.0/24, 1 successors, FD is 409600, serno 7
via 172.16.1.6 (409600/128256), Ethernet1/1
P 172.16.1.8/30, 1 successors, FD is 307200, serno 8
via 172.16.1.6 (307200/281600), Ethernet1/1
P 172.16.1.4/30, 1 successors, FD is 281600, serno 2
via Connected, Ethernet1/1
P 172.16.1.0/30, 1 successors, FD is 281600, serno 1
via Connected, Ethernet1/0
R2#
6、导致R2 无法ping 路由器R4 所连接的10.1.X.0/24 的网络主要原因是：R1
本身属于主类的边界，其会将本地路由表中的子网向主类网络自动汇总。而R4
也属于主类的界，也会与R1 做出相同的动作。因此R2 会从不同的接口，收到相
同的汇总路由，即10.0.0.0/8 网络路由。由于R2 在比较了两条路由的可行距离
后，选择了较小的FD 值的路由，即R1 通告的10.0.0.0/8 汇总路由。而忽略了
另外一个接口收到汇总路由。其实真正的原因，并不是路由选择出错，而是自动
汇总不能做到精确的控制原因导致的。
7、为了解决汇总问题，需要在R1 和R4 上关闭自动汇总，而采用手工汇总。配
置如下：
R1(config)#router eigrp 50
R1(config-router)#no auto-summary
批注 [stanley24]:
all-links 参数是显示所有
链路。
批注 [stanley25]: 到底
10.0.0.0/8 网络有两条路
由。
注意两条路由的FD 值是不同
的。
批注 [stanley26]: 关闭自
动汇总。
18
R1(config-router)#exit
R1(config)#
R1(config)#interface fastEthernet 0/1
R1(config-if)#ip summary-address eigrp 50 10.1.0.0 255.255.252.0
R1(config-if)#exit
R1(config)#exit
R4(config)#router eigrp 50
R4(config-router)#no auto-summary
R4(config-router)#exit
R4(config)#
R4(config)#interface fastEthernet 0/0
R4(config-if)#ip summary-address eigrp 50 10.1.16.0 255.255.252.0
R4(config-if)#exit
R4(config)#exit
8、再次查看R2 路由表：
R2#show ip route
Gateway of last resort is not set
172.16.0.0/30 is subnetted, 3 subnets
D 172.16.1.8 [90/307200] via 172.16.1.6, 00:21:08, Ethernet1/1
C 172.16.1.4 is directly connected, Ethernet1/1
C 172.16.1.0 is directly connected, Ethernet1/0
10.0.0.0/22 is subnetted, 2 subnets
D 10.1.0.0 [90/409600] via 172.16.1.1, 00:03:13, Ethernet1/0
D 10.1.16.0 [90/435200] via 172.16.1.6, 00:01:02, Ethernet1/1
D 192.168.0.0/24 [90/409600] via 172.16.1.6, 00:21:08, Ethernet1/1
D 192.168.1.0/24 [90/409600] via 172.16.1.6, 00:21:08, Ethernet1/1
D 192.168.2.0/24 [90/409600] via 172.16.1.6, 00:21:08, Ethernet1/1
D 192.168.3.0/24 [90/409600] via 172.16.1.6, 00:21:08, Ethernet1/1
R2#
9、再次使用ping 命令确认网络可达性：
R2#ping 10.1.0.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.0.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 16/69/145 ms
R2#ping 10.1.1.1
Type escape sequence to abort.
批注 [stanley27]: 进行手
工汇总，其汇总路由为
10.1.0.0/22
批注 [stanley28]: 被汇总
的/22 位网络路由。
19
Sending 5, 100-byte ICMP Echos to 10.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 16/44/64 ms
R2#ping 10.1.16.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.16.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 60/97/140 ms
R2#ping 10.1.17.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.17.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 48/93/149 ms
R2#
10、再次查看R2 的路由表：
R2#show ip route
Gateway of last resort is not set
172.16.0.0/30 is subnetted, 3 subnets
D 172.16.1.8 [90/307200] via 172.16.1.6, 00:23:45, Ethernet1/1
C 172.16.1.4 is directly connected, Ethernet1/1
C 172.16.1.0 is directly connected, Ethernet1/0
10.0.0.0/22 is subnetted, 2 subnets
D 10.1.0.0 [90/409600] via 172.16.1.1, 00:05:49, Ethernet1/0
D 10.1.16.0 [90/435200] via 172.16.1.6, 00:03:38, Ethernet1/1
D 192.168.0.0/24 [90/409600] via 172.16.1.6, 00:23:45, Ethernet1/1
D 192.168.1.0/24 [90/409600] via 172.16.1.6, 00:23:45, Ethernet1/1
D 192.168.2.0/24 [90/409600] via 172.16.1.6, 00:23:45, Ethernet1/1
D 192.168.3.0/24 [90/409600] via 172.16.1.6, 00:23:45, Ethernet1/1
R2#
11、为了能够有效的减少路由表的大小，还可以通过EIGRP 对192.168.X.0/24
的C 类网络路由进行手工路由汇总，具体配置如下：
R3(config)#router eigrp 50
R3(config-router)#no auto-summary
R3(config-router)#exit
R3(config)#
R3(config)#interface ethernet 1/1
R3(config-if)#ip summary-address eigrp 50 192.168.0.0 255.255.252.0
R3(config-if)#exit
批注 [stanley29]:
192.168.X.0/24 具体路由。
批注 [stanley30]: 虽然在
R3 上配置的是超网汇总，仍
然需要在R3 的EIGRP 进程中
关闭自动汇总特性，否则，
EIGRP 还是会向外通告具体
路由。
20
R3(config)#
R3(config)#inter ethernet 1/0
R3(config-if)#ip summary-address eigrp 50 192.168.0.0 255.255.252.0
R3(config-if)#exit
R3(config)#
12、查看R4 和R2 的路由表：
R4#show ip route
Gateway of last resort is not set
172.16.0.0/30 is subnetted, 3 subnets
C 172.16.1.8 is directly connected, FastEthernet0/0
D 172.16.1.4 [90/284160] via 172.16.1.9, 00:02:41, FastEthernet0/0
D 172.16.1.0 [90/309760] via 172.16.1.9, 00:02:23, FastEthernet0/0
10.0.0.0/8 is variably subnetted, 6 subnets, 2 masks
D 10.1.0.0/22 [90/437760] via 172.16.1.9, 00:02:23, FastEthernet0/0
C 10.1.19.0/24 is directly connected, Loopback0
C 10.1.18.0/24 is directly connected, Loopback0
C 10.1.17.0/24 is directly connected, Loopback0
D 10.1.16.0/22 is a summary, 00:03:33, Null0
C 10.1.16.0/24 is directly connected, Loopback0
D 192.168.0.0/22 [90/156160] via 172.16.1.9, 00:02:41, FastEthernet0/0
R4#
R2#show ip route
Gateway of last resort is not set
172.16.0.0/30 is subnetted, 3 subnets
D 172.16.1.8 [90/307200] via 172.16.1.6, 00:02:54, Ethernet1/1
C 172.16.1.4 is directly connected, Ethernet1/1
C 172.16.1.0 is directly connected, Ethernet1/0
10.0.0.0/22 is subnetted, 2 subnets
D 10.1.0.0 [90/409600] via 172.16.1.1, 00:16:13, Ethernet1/0
D 10.1.16.0 [90/435200] via 172.16.1.6, 00:02:54, Ethernet1/1
D 192.168.0.0/22 [90/409600] via 172.16.1.6, 00:02:54, Ethernet1/1
R2#
13、使用ping 命令确认路由有效性：
R2#ping 192.168.0.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.1, timeout is 2 seconds:
批注 [stanley31]: 从R3 收
到的手工汇总的路由。
批注 [stanley32]: 从R3 收
到的手工汇总的路由。
21
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/28/60 ms
R2#
R4#ping 192.168.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 24/37/48 ms
R4#
14、通过本实验可以看出，虽然EIGRP 的自动汇总能够为网络配置带来便捷，但
是其依赖于IP 子网的规划。如果遇到糟糕的子网规划，则需要小心使用自动特
性。
38、实验完成。

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