任务 3:配置基于下一跳 IP 的静态路由
步骤 1:在 R2 上,创建一条到 192.168.1.0/24 的静态路由,下一跳 IP 地址为 192.168.12.1
R2(config)#ip route 192.168.1.0 255.255.255.0 192.168.12.1
步骤 2:检查 R2 的路由表,发现了一条“S”的路由
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 192.168.12.0/24 is directly connected, FastEthernet0/0.12 C 192.168.24.0/24 is directly connected, FastEthernet0/0.24 C 192.168.23.0/24 is directly connected, FastEthernet0/0.23 S 192.168.1.0/24 [1/0] via 192.168.12.1
步骤 3:在 R2 上,尝试再增加到 192.168.1.0/24,但下一跳为 192.168.12.2,这个下一 跳是自己的 IP 地址,看看发生了什么?为什么会出现报错?错在哪里?
R2(config)#ip route 192.168.1.0 255.255.255.0 192.168.12.2 %Invalid next hop address (it's this router)
步骤 4:在 R2 上,尝试增加一条静态路由,目标网络192.168.1.0,掩码为 255.255.0.0, 下一跳是 192.168.12.2,看看发生了什么?为什么会出现报错?错在哪里?
R2(config)#ip route 192.168.1.0 255.255.0.0 192.168.12.1 %Inconsistent address and mask
步骤 5:在 R2 上,创建一条静态路由,目标网络是 192.168.1.0/24,下一跳是 192.168.23.3 (R3),显然这条路由是错误的,通过 R3 根本无法到达 192.168.1.0/24
R2(config)#ip route 192.168.1.0 255.255.255.0 192.168.23.3
步骤 6:观察 R2 的路由表,会发现到 192.168.1.0/24 有 2 个下一跳 IP,说明静态路由没有 唯一性,到一个目标网段完全可以有多个下一跳
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 192.168.12.0/24 is directly connected, FastEthernet0/0.12 C 192.168.24.0/24 is directly connected, FastEthernet0/0.24 C 192.168.23.0/24 is directly connected, FastEthernet0/0.23 S 192.168.1.0/24 [1/0] via 192.168.23.3 [1/0] via 192.168.12.1
步骤 7:在 R2 上,使用 no 命令,将错误的静态路由删掉
R2(config)#no ip route 192.168.1.0 255.255.255.0 192.168.23.3
步骤 8:再次检查 R2 的路由表,发现到 192.168.1.0/24 只有一个下一跳
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 192.168.12.0/24 is directly connected, FastEthernet0/0.12 C 192.168.24.0/24 is directly connected, FastEthernet0/0.24 C 192.168.23.0/24 is directly connected, FastEthernet0/0.23 S 192.168.1.0/24 [1/0] via 192.168.12.1
步骤 9:使用 show ip route static 可以把路由表中的静态路由提取出来单独查看
R2#show ip route static S 192.168.1.0/24 [1/0] via 192.168.12.1 R2#