本文主要描述通過策略路由PBR和IP服務水平協議SLA來實現數據包的分流。
假設：Outside上設置默認路由到192.168.1.0/24，下一條指向R6：ip route 0.0.0.0 255.255.255.0 1.1.56.6
要求：但是從源IP:5.5.5.5/32出來的數據包必須走R4：並且保證鏈路的暢通性：
R5基本配置：
interface Loopback0
ip address 5.5.5.5 255.255.255.255
interface FastEthernet1/0
ip address 1.1.56.5 255.255.255.0
interface FastEthernet1/1
ip address 1.1.45.5 255.255.255.0
ip policy route-map AAA
ip local policy route-map AAA
ip route 0.0.0.0 0.0.0.0 1.1.56.6
route-map AAA permit 10
match interface Loopback0
set ip next-hop 1.1.45.4
R5#debug ip policy
R5#ping 4.4.4.4 sou lo0 ：這裏注意：如果是本地產生的流量，route-map默認是不匹配的，需要啓用：[ip local policy route-map AAA]：才能讓本地流量匹配AAA：
*Dec 3 18:48:32.823: IP: s=5.5.5.5 (local), d=4.4.4.4, len 100, policy match
*Dec 3 18:48:32.823: IP: route map AAA, item 10, permit
*Dec 3 18:48:32.827: IP: s=5.5.5.5 (local), d=4.4.4.4 (FastEthernet1/1), len 100, policy routed
*Dec 3 18:48:32.827: IP: local to FastEthernet1/1 1.1.45.4
此時如果關閉R4的F1/1接口：此時R5再pingR4：鏈路是否正常？
【不通】：解釋：route-map無法區分下一跳是否可達。但是可以結合SLA來實現：
ip sla monitor 1
type echo protocol ipIcmpEcho 1.1.45.4
frequency 10
ip sla monitor schedule 1 life forever start-time now
track 2 rtr 1
route-map AAA permit 10
match interface Loopback0
set ip next-hop verify-availability 1.1.45.4 1 track 2
R5#ping 4.4.4.4 sou lo0 ：這裏注意：此時如果你關閉R4的F1/1，即使流量匹配了route-map，但是策略還是不會被執行，走正常的路由表：詳細見以下debug信息
Wan30#debug ip policy
*Dec 3 18:49:42.115: IP: s=5.5.5.5 (local), d=4.4.4.4, len 100, policy match
*Dec 3 18:49:42.115: IP: route map AAA, item 10, permit
*Dec 3 18:49:42.115: IP: s=5.5.5.5 (local), d=4.4.4.4, len 100, policy rejected -- normal forwarding
通過以上配置實驗，數據包分流實現。
