简介：来自R1的数据包经过R2，R4在经过R3出去，数据包回来的时候R3经过R2，R1不经过R4
R1:
conf ter
int loo 0
ip add 1.1.1.1255.255.255.0
no shu
ex
int f1/0
ip add 192.168.1.1255.255.255.0
no shu
ex
router rip
ver 2
no au
net 192.168.1.0
net 1.0.0.0
R2:
conf ter
int f1/0
ip add 192.168.1.2255.255.255.0
no shu
ex
int f1/1
ip add 192.168.2.1255.255.255.0
no shu
ex
int f2/0
ip add 192.168.3.2255.255.255.0
no shu
ex
int f2/1
ip add 192.168.4.1255.255.255.0
no shu
ex
router rip
ver 2
no au
net 192.168.1.0
net 192.168.2.0
net 192.168.3.0
net 192.168.4.0
R3:
conf ter
int loo 0
ip add 3.3.3.3255.255.255.0
no shu
ex
int f1/0
ip add 192.168.4.2255.255.255.0
no shu
ex
router rip
ver 2
no au
net 192.168.4.0
net 3.0.0.0
exit
R4:
conf ter
int f1/0
ip add 192.168.2.2255.255.255.0
no shu
ex
int f1/1
ip add 192.168.3.1255.255.255.0
no shu
exit
router rip
ver 2
no au
net 192.168.2.0
net 192.168.3.0
exit
R2:
acc 100 permit iphost 1.1.1.1 host 3.3.3.3
route-map test01permit 10
match ip address 100
set ip next-hop192.168.2.2
exit
int f1/0
ip policy route-maptest01
exit
R4:
acc 120 permit iphost 1.1.1.1 host 3.3.3.3
route-map test01permit 10
match ip address 120
set ip next-hop192.168.3.2
exit
int f1/0
ip policy route-maptest01
exit
测试：
R1#traceroute3.3.3.3 source 1.1.1.1
Type escape sequenceto abort.
Tracing the route to3.3.3.3
1 192.168.1.2 612 msec 548 msec 376 msec
2 192.168.2.2 540 msec 576 msec 692 msec
3 192.168.3.2 448 msec 1104 msec 420 msec
4 192.168.4.2 656 msec 872 msec 1280 msec
R3#traceroute1.1.1.1 source 3.3.3.3
Type escape sequenceto abort.
Tracing the route to1.1.1.1
1 192.168.4.1 1064 msec 432 msec 392 msec
2 192.168.1.1 528 msec * 792 msec
案例延伸:来自R3的数据包经过R4，R2在经过R1回去，数据包回来的时候R1经过R2，R4到达R3
R2:
acc 110 permit iphost 3.3.3.3 host 1.1.1.1
route-map test03permit 10
match ip address 110
set ip next-hop192.168.3.1
exit
int f2/1
ip policy route-maptest03
exit
R4:
acc 140 permit iphost 3.3.3.3 host 1.1.1.1
route-map test04permit 10
match ip address 140
set ip next-hop192.168.2.1
exit
int f1/1
ip policy route-maptest04
exit
测试：
R3#traceroute1.1.1.1 source 3.3.3.3
Type escape sequenceto abort.
Tracing the route to1.1.1.1
1 192.168.4.1 348 msec 144 msec 284 msec
2 192.168.3.1 668 msec 696 msec 940 msec
3 192.168.2.1 404 msec 792 msec 472 msec
4 192.168.1.1 728 msec 576 msec 776msec
R1#traceroute3.3.3.3 source 1.1.1.1
Type escape sequenceto abort.
Tracing the route to3.3.3.3
1 192.168.1.2 220 msec 292 msec 1480 msec
2 192.168.2.2 448 msec 464 msec 440 msec
3 192.168.3.2 356 msec 588 msec 440 msec
4 192.168.4.2 760 msec 652 msec 484msec