月份：2023年1月

路由策略配置

1.如图1，配置各个接口的IP地址（略）

2.启用OSPF协议（略）

ospf默认1Gbps链路开销为1（经过几个链路开销就是几）

R1到4.4.4.4的上下两条路径的开销都为3，如图2

改变下边接口的开销来影响流量的路径

[R1]int g0/0/2
[R1-GigabitEthernet0/0/2]ospf cost 2

3.路由过滤（路由策略配置）

配置要求：

R1后边的网段不能访问7.7.7.7

R2、R3可以访问7.7.7.7

R1配置命令：

[R1]acl 2023	
[R1-acl-basic-2023]rule 5 deny source 7.7.7.0 0.0.0.255
[R1-acl-basic-2023]rule 10 per
[R1-acl-basic-2023]qu
[R1]ospf 1
[R1-ospf-1]filter-policy 2023 import 

此时，PC1、PC2无法访问7.7.7.7，R2、R3可以正常访问

PC>ping 7.7.7.7

Ping 7.7.7.7: 32 data bytes, Press Ctrl_C to break
Request timeout!
Request timeout!
Request timeout!
Request timeout!
Request timeout!

--- 7.7.7.7 ping statistics ---
  5 packet(s) transmitted
  0 packet(s) received
  100.00% packet loss

<R2>ping -a 2.2.2.2 7.7.7.7
  PING 7.7.7.7: 56  data bytes, press CTRL_C to break
    Reply from 7.7.7.7: bytes=56 Sequence=1 ttl=127 time=20 ms
    Reply from 7.7.7.7: bytes=56 Sequence=2 ttl=127 time=20 ms
    Reply from 7.7.7.7: bytes=56 Sequence=3 ttl=127 time=20 ms
    Reply from 7.7.7.7: bytes=56 Sequence=4 ttl=127 time=30 ms
    Reply from 7.7.7.7: bytes=56 Sequence=5 ttl=127 time=20 ms

  --- 7.7.7.7 ping statistics ---
    5 packet(s) transmitted
    5 packet(s) received
    0.00% packet loss
    round-trip min/avg/max = 20/22/30 ms

<R3>ping -a 3.3.3.3 7.7.7.7
  PING 7.7.7.7: 56  data bytes, press CTRL_C to break
    Reply from 7.7.7.7: bytes=56 Sequence=1 ttl=127 time=20 ms
    Reply from 7.7.7.7: bytes=56 Sequence=2 ttl=127 time=20 ms
    Reply from 7.7.7.7: bytes=56 Sequence=3 ttl=127 time=30 ms
    Reply from 7.7.7.7: bytes=56 Sequence=4 ttl=127 time=20 ms
    Reply from 7.7.7.7: bytes=56 Sequence=5 ttl=127 time=20 ms

  --- 7.7.7.7 ping statistics ---
    5 packet(s) transmitted
    5 packet(s) received
    0.00% packet loss
    round-trip min/avg/max = 20/22/30 ms

*更多路由策略内容详见后续更新的BGP相关知识