基本配置B1的配置命令：
B1(config)#interface serial 0
B1(config-if)#ip address .1 255.255.255.0
B1(config-if)#clock rate 64000
B1(config-if)#ip address .1 255.255.255.0 secondary
B1(config-if)#ip address .1 255.255.255.0 secondary
B1(config-if)#ip address .1 255.255.255.0 secondary
B1(config-if)#ip address .1 255.255.255.0 secondary
B1(config-if)#ip address .1 255.255.255.0
B1(config)#router ospf 10
B1(config-router)#router-id .1
B1(config-router)#network .0 255.255.255.255 area 0
B9的配置命令：
B9(config-if)#interface serial 0
B9(config-if)#ip address .3 255.255.255.0
B9(config)#interface loopback 0
B9(config-if)#ip address .3 255.255.255.0
B9(config-if)#ip ospf network point-to-point
B9(config-if)#interface eth 0
B9(config-if)#ip address 213.1.1.3 255.255.255.0
B9(config)#ip route .0 0.0.0.0 23.1.1.2
B4的配置命令：
B4(config-if)#interface Loopback0
B4(config-if)#ip address .2 255.255.255.0
B4(config-if)# ip ospf network point-to-point
B4(config)#interface Ethernet0
B4(config-if)#ip address 213.1.1.2 255.255.255.0
B4(config)#interface Serial1
B4(config-if)#ip address .2 255.255.255.0
B4(config)#router ospf 10
B4(config-router)#router-id .2
B4(config-router)#network .0 255.255.255.255 area 0
B4(config-router)#default-information originate always//用ospf通告一条默认给B1，always参数的作用是不需要B4本省有静态默认的存在。
监视与测试配置
查看B1的路由表发现，B4将其与B1相连的接口IP通告给了B1这位默认路由
Gateway of last resort is .2 to network 0.0.0.0
.0/24 is subnetted, 5 subnets
C .0 is directly connected, Loopback0
C .0 is directly connected, Loopback0
C .0 is directly connected, Loopback0
C .0 is directly connected, Loopback0
C .0 is directly connected, Loopback0
.0/24 is subnetted, 1 subnets
O .0 [110/65] vi.2, 00:16:33, Serial0
.0/24 is subnetted, 1 subnets
O .0 [110/128] vi.2, 00:16:33, Serial0
O 213.1.1.0/24 [110/74] vi.2, 00:16:34, Serial0
.0/24 is subnetted, 1 subnets
C .0 is directly connected, Serial0
O*E2 .0/0 [110/1] vi.2, 00:17:36, Serial0
下面配置B4，是B1的1.1.X.1/24网络和.0/24网络分别B4的S0和eth0接口访问B9的3.3.3.0/24网络。
B4(config)#route-map to-B9
B4(config-route-map)#match ip address 10
B4(config-route-map)#set default interface serial 0
B4(config)#access-list 10 permit .0 0.0.3.255
B4(config)#access-list 20 permit .0 0.0.0.255
B4(config)#route-map to-B9 permit 20
B4(config-route-map)#match ip address 20
B4(config-route-map)#set default interface e0
应用到接口
B4(config)#interface serial 1
B4(config-if)#ip policy route-map to-B9
打开策略运行调试输出：
B4(config)#debug ip policy
Policy routing debugging is on
Set default interface这条命令和set ip next-hop的区别是：前者先检查路由表，路由有到目的地址的路径（不算默认路由），则按路由路由表进行路由，如果路由表中没有到达目的地址的明确路径，则用设置的策略路由发送。
在B1发起ping。验证策略路由情况：
在B4查看策略路由debug输出，因为B4没有针对.0/24的路由，因此按照策略路由方式转发
B1#ping
Protocol [ip]:
Target IP address: .3
Repeat count [5]:
Datagram size [100]:
Timeout in seconds [2]:
Extended commands [n]: y
Source address or interface: .1
Type of service [0]:
Set DF bit in IP header? [no]:
Validate reply data? [no]:
Data pattern [0xABCD]:
Loose, Strict, Record, Timestamp, Verbose[none]:
Sweep range of sizes [n]:
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to .3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 72/74/76 ms