CCNP-20 ISIS试验3
实验拓扑：
实验要求：R1与R2分别配置集成的ISIS，先把他们分在同一个区域，然后分别起几个LOOPBACK接口，IP地址配置成连续的子网地址，然后配置层1的汇聚，观察结果，然后再把两台路由其配置到不同的区域，同样作汇总，观察结果。
试验目的：掌握集成ISIS路由汇总的配置方法和应用环境。
试验配置：
R1：
R1(config)#router isis
R1(config-router)#net 49.0001.1111.1111.1111.00
R1(config-router)#exit
R1(config)#int loop0
R1(config-if)#ip add 192.168.1.1 255.255.255.0
R1(config-if)#ip router isis
R1(config-if)#exit
R1(config)#int loop1
R1(config-if)#ip add 192.168.2.1 255.255.255.0
R1(config-if)#ip router isis
R1(config-if)#exit
R1(config)#int loop2
R1(config-if)#ip add 192.168.3.1 255.255.255.0
R1(config-if)#ip router isis
R1(config-if)#exit
R1(config)#int loop3
R1(config-if)#ip add 192.168.4.1 255.255.255.0
R1(config-if)#ip router isis
R1(config-if)#exit
R1(config)#int f0/0
R1(config-if)#ip add 10.1.1.1 255.255.255.0
R1(config-if)#ip router isis
R1(config-if)#no shu
R2：
R2(config)#router isis
R2(config-router)#net 49.0001.2222.2222.2222.00
R2(config-router)#exit
R2(config)#int loop0
R2(config-if)#ip add 199.99.1.1 255.255.255.0
R2(config-if)#ip router isis
R2(config-if)#exit
R2(config)#int loop1
R2(config-if)#ip add 199.99.2.1 255.255.255.0
R2(config-if)#ip router isis
R2(config-if)#exit
R2(config)#int loop2
R2(config-if)#ip add 199.99.3.1 255.255.255.0
R2(config-if)#ip router isis
R2(config-if)#exit
R2(config)#int loop3
R2(config-if)#ip add 199.99.4.1 255.255.255.0
R2(config-if)#ip router isis
R2(config-if)#exit
R2(config)#int f0/0
R2(config-if)#ip add 10.1.1.2 255.255.255.0
R2(config-if)#ip router isis
R2(config-if)#no shu
好了，下面我们在R1上show ip route查看一下路由表：
R1#show ip route
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
i L1 199.99.3.0/24 [115/20] via 10.1.1.2, FastEthernet0/0
C 192.168.4.0/24 is directly connected, Loopback3
i L1 199.99.2.0/24 [115/20] via 10.1.1.2, FastEthernet0/0
i L1 199.99.1.0/24 [115/20] via 10.1.1.2, FastEthernet0/0
10.0.0.0/24 is subnetted, 1 subnets
C 10.1.1.0 is directly connected, FastEthernet0/0
C 192.168.1.0/24 is directly connected, Loopback0
C 192.168.2.0/24 is directly connected, Loopback1
i L1 199.99.4.0/24 [115/20] via 10.1.1.2, FastEthernet0/0
C 192.168.3.0/24 is directly connected, Loopback2
有四条i L1的路由，然后我们在R2上做层一的汇总，看看可不可以：
R2(config)#router isis
R2(config-router)#summary-address 199.99.0.0 255.255.0.0 level-1
然后在R1上看效果：
R1#show ip route
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
i L1 199.99.3.0/24 [115/20] via 10.1.1.2, FastEthernet0/0
C 192.168.4.0/24 is directly connected, Loopback3
i L1 199.99.2.0/24 [115/20] via 10.1.1.2, FastEthernet0/0
i L1 199.99.1.0/24 [115/20] via 10.1.1.2, FastEthernet0/0
10.0.0.0/24 is subnetted, 1 subnets
C 10.1.1.0 is directly connected, FastEthernet0/0
C 192.168.1.0/24 is directly connected, Loopback0
C 192.168.2.0/24 is directly connected, Loopback1
i L1 199.99.4.0/24 [115/20] via 10.1.1.2, FastEthernet0/0
C 192.168.3.0/24 is directly connected, Loopback2
没有效果，还是4条，在R2上再看一下LSDB：
R2#show isis database detail
IS-IS Level-1 Link State Database:
LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OL
R1.00-00 0x00000006 0xB598 904 0/0/0
Area Address: 49.0001
NLPID: 0xCC
Hostname: R1
IP Address: 192.168.1.1
Metric: 10 IP 10.1.1.0 255.255.255.0
Metric: 10 IP 192.168.1.0 255.255.255.0
Metric: 10 IP 192.168.2.0 255.255.255.0
Metric: 10 IP 192.168.3.0 255.255.255.0
Metric: 10 IP 192.168.4.0 255.255.255.0
Metric: 10 IS R2.05
R2.00-00 * 0x00000007 0xA27A 910 0/0/0
Area Address: 49.0001
NLPID: 0xCC
Hostname: R2
IP Address: 199.99.1.1
Metric: 10 IP 10.1.1.0 255.255.255.0
Metric: 10 IP 199.99.1.0 255.255.255.0
Metric: 10 IP 199.99.2.0 255.255.255.0
Metric: 10 IP 199.99.3.0 255.255.255.0
Metric: 10 IP 199.99.4.0 255.255.255.0
Metric: 10 IS R2.05
R2.05-00 * 0x00000001 0x0A48 906 0/0/0
Metric: 0 IS R2.00
Metric: 0 IS R1.00
并没有看到汇总路由的出现，由此得出结论：
在集成ISIS中，L1的路由是不可以被汇总的。
下面我们把R2加入到另外一个区域：
R2(config)#router isis
R2(config-router)#no net 49.0001.2222.2222.2222.00
R2(config-router)#net 49.0002.2222.2222.2222.00
好了，再到R1上观察路由表：
R1#show ip route
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
i L2 199.99.3.0/24 [115/20] via 10.1.1.2, FastEthernet0/0
C 192.168.4.0/24 is directly connected, Loopback3
i L2 199.99.2.0/24 [115/20] via 10.1.1.2, FastEthernet0/0
i L2 199.99.1.0/24 [115/20] via 10.1.1.2, FastEthernet0/0
10.0.0.0/24 is subnetted, 1 subnets
C 10.1.1.0 is directly connected, FastEthernet0/0
C 192.168.1.0/24 is directly connected, Loopback0
C 192.168.2.0/24 is directly connected, Loopback1
i L2 199.99.4.0/24 [115/20] via 10.1.1.2, FastEthernet0/0
C 192.168.3.0/24 is directly connected, Loopback2
原来的4条L1的路由都变成了L2的路由了，然后我们在R2上将他们进行汇总：
R2(config-router)#summary-address 199.99.0.0 255.255.0.0 level-2
汇总完成后，先在R2上查看一下路由表：
R2#show ip route
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
C 199.99.3.0/24 is directly connected, Loopback2
i L2 192.168.4.0/24 [115/20] via 10.1.1.1, FastEthernet0/0
C 199.99.2.0/24 is directly connected, Loopback1
C 199.99.1.0/24 is directly connected, Loopback0
10.0.0.0/24 is subnetted, 1 subnets
C 10.1.1.0 is directly connected, FastEthernet0/0
i L2 192.168.1.0/24 [115/20] via 10.1.1.1, FastEthernet0/0
i L2 192.168.2.0/24 [115/20] via 10.1.1.1, FastEthernet0/0
C 199.99.4.0/24 is directly connected, Loopback3
i L2 192.168.3.0/24 [115/20] via 10.1.1.1, FastEthernet0/0
i su 199.99.0.0/16 [115/10] via 0.0.0.0, Null0
会发现多了一条i su 199.99.0.0/16 [115/10] via 0.0.0.0, Null0的路由，这条路由的意思就是符合199.99.0.0/16的路由全部丢弃掉，也许你该有疑问，为什么要丢弃掉，丢弃掉的话那四条路由不就不可达了吗？答案是可以到达，路由表示根据最长匹配的原则来进行路由转发的，上面有那四条的路由，所以就可以到达了。。。下面再到R1上查看路由表：
R1#show ip route
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
C 192.168.4.0/24 is directly connected, Loopback3
10.0.0.0/24 is subnetted, 1 subnets
C 10.1.1.0 is directly connected, FastEthernet0/0
C 192.168.1.0/24 is directly connected, Loopback0
C 192.168.2.0/24 is directly connected, Loopback1
C 192.168.3.0/24 is directly connected, Loopback2
i L2 199.99.0.0/16 [115/20] via 10.1.1.2, FastEthernet0/0
原来的4条路由没有了，变成了一条汇聚路由，OK，汇总成功，按照同样的方法，在R1上配置汇总：
R1(config-router)#summary-address 192.168.0.0 255.255.0.0 level-2
然后在R2上查看路由表：
R2#show ip route
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
C 199.99.3.0/24 is directly connected, Loopback2
C 199.99.2.0/24 is directly connected, Loopback1
C 199.99.1.0/24 is directly connected, Loopback0
10.0.0.0/24 is subnetted, 1 subnets
C 10.1.1.0 is directly connected, FastEthernet0/0
C 199.99.4.0/24 is directly connected, Loopback3
i su 199.99.0.0/16 [115/10] via 0.0.0.0, Null0
i L2 192.168.0.0/16 [115/20] via 10.1.1.1, FastEthernet0/0
可以看到汇总路由。
我们再查看一下R1的LSDB：
R1#show isis database detail
IS-IS Level-2 Link State Database:
LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OL
R1.00-00 * 0x0000000E 0xB0A2 1186 0/0/0
Area Address: 49.0001
NLPID: 0xCC
Hostname: R1
IP Address: 192.168.1.1
Metric: 10 IS R2.05
Metric: 10 IP 10.1.1.0 255.255.255.0
Metric: 10 IP 192.168.0.0 255.255.0.0
R2.00-00 0x0000000C 0x0762 1124 0/0/0
Area Address: 49.0002
NLPID: 0xCC
Hostname: R2
IP Address: 199.99.1.1
Metric: 10 IS R2.05
Metric: 10 IP 10.1.1.0 255.255.255.0
Metric: 10 IP 199.99.0.0 255.255.0.0
R2.05-00 0x00000002 0x9742 1086 0/0/0
Metric: 0 IS R2.00
Metric: 0 IS R1.00
看到了两条汇总的信息，一条是自己的，一条是R2的。由此我们可以得出另一个结论：
在ISIS中，L2的路由可以被汇总。
实验结论：掌握ISIS路由汇总的配置方法和知道L1的路由是不可以被汇总的。
本文转自loveme2351CTO博客，原文链接：http://blog.51cto.com/loveme23/48139 ，如需转载请自行联系原作者
