验证OSPF对外部路由的选路规则

[1]O E1优于O E2

[2]在同样的情况下，Cost越小越优先

[3]在cost相同的情况下，选择到达ASBR最优的路径

下面来通过实验来验证该规则：

[案例1]当外部路由都是O E1的情况

基本配置：（注意ASBR的配置）

R1:

interface Loopback0

ip address 1.1.1.1 255.255.255.0

ip ospf network point-to-point

!

interface Serial1/0

ip address 12.1.1.1 255.255.255.0

!

interface Serial2/0

ip address 13.1.1.1 255.255.255.0

!

router ospf 1

redistribute rip subnets metric-type 1

network 12.1.1.0 0.0.0.255 area 0

!

router rip

version 2

network 13.0.0.0

distance 109

会发生路由抖动,故将其改详解看等级三实验手册1.3)

no auto-summary

!

　　R2:

interface Loopback0

ip address 2.2.2.2 255.255.255.0

ip ospf network point-to-point

!

interface Serial1/0

ip address 24.1.1.2 255.255.255.0

!

interface Serial2/0

ip address 12.1.1.2 255.255.255.0

!

router ospf 1

network 12.1.1.0 0.0.0.255 area 0

network 24.1.1.0 0.0.0.255 area 0

!

　　R3:

interface Loopback0

ip address 3.3.3.3 255.255.255.0

ip ospf network point-to-point

!

interface Serial1/0

ip address 13.1.1.3 255.255.255.0

!

interface Serial2/0

ip address 35.1.1.3 255.255.255.0

!

router rip

version 2

network 3.0.0.0

network 13.0.0.0

network 35.0.0.0

no auto-summary

!

　　R4:

interface Loopback0

ip address 4.4.4.4 255.255.255.0

ip ospf network point-to-point

!

interface Serial1/0

ip address 45.1.1.4 255.255.255.0

!

interface Serial2/0

ip address 24.1.1.4 255.255.255.0

!

router ospf 1

network 24.1.1.0 0.0.0.255 area 0

network 45.1.1.0 0.0.0.255 area 1

!

　　R5:

interface Loopback0

ip address 5.5.5.5 255.255.255.0

ip ospf network point-to-point

!

interface Serial1/0

ip address 35.1.1.5 255.255.255.0

!

interface Serial2/0

ip address 45.1.1.5 255.255.255.0

!

router ospf 1

redistribute rip subnets metric-type 1

network 45.1.1.0 0.0.0.255 area 1

!

router rip

version 2

network 35.0.0.0

distance 109

no auto-summary

!