ip default-network在EIGRP中的应用[文档]
默认路由系列4/5



在RIP协议下，ip default-network [直链网络主网号] 就可以把默认路由通告到网络内部。但在EIGRP和IGRP协议下，这不足以让他们通告出默认路由。
以下以EIGRP为例：
-------------------------------------------------------------------------------------------------------
R1#show run
Building configuration...

Current configuration : 953 bytes
!
version 12.3
!
hostname R1
!
interface Loopback0

ip address 1.1.1.1 255.255.255.0
!
interface FastEthernet0/0

ip address 112.1.1.1 255.255.255.0
!
router eigrp 100

network 112.0.0.0

auto-summary
!

end
-------------------------------------------------------------------------------------------------------
R2#show run
Building configuration...

Current configuration : 1043 bytes
!
version 12.3
!
hostname R2
!
interface Loopback0

ip address 2.2.2.2 255.255.255.0
!
interface FastEthernet0/0

ip address 112.1.1.2 255.255.255.0
!
interface Serial1/1

ip address 23.1.1.2 255.255.255.0
!
router eigrp 100

network 23.0.0.0

//EIGRP与RIP的不同

network 112.0.0.0

auto-summary
!


ip default-network 23.0.0.0
ip route 0.0.0.0 0.0.0.0 23.1.1.3
!
end
-------------------------------------------------------------------------------------------------------
R3#show run
Building configuration...

Current configuration : 934 bytes
!
version 12.3
!
hostname R3
!
interface Loopback0

ip address 3.3.3.3 255.255.255.0
!

interface Serial1/0

ip address 23.1.1.3 255.255.255.0
!
ip route 0.0.0.0 0.0.0.0 23.1.1.2
!
end
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在R2 上没有配置network 23.0.0.0的时候，R1的路由表
R1#show ip ro
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is not set


1.0.0.0/24 is subnetted, 1 subnets
C
1.1.1.0 is directly connected, Loopback0

112.0.0.0/24 is subnetted, 1 subnets
C
112.1.1.0 is directly connected, FastEthernet0/0

R2的路由表为
R2#show ip ro
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 23.1.1.3 to network 0.0.0.0


2.0.0.0/24 is subnetted, 1 subnets
C
2.2.2.0 is directly connected, Loopback0

*
23.0.0.0/24 is subnetted, 1 subnets


//由ip default-network产生
C
23.1.1.0 is directly connected, Serial1/1

112.0.0.0/24 is subnetted, 1 subnets
C
112.1.1.0 is directly connected, FastEthernet0/0
S*
0.0.0.0/0 [1/0] via 23.1.1.3
-------------------------------------------------------------------------------------------------------

配置了后R1路由表为
R1#show ip ro
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 112.1.1.2 to network 23.0.0.0


1.0.0.0/24 is subnetted, 1 subnets
C
1.1.1.0 is directly connected, Loopback0
D*
23.0.0.0/8 [90/2172416] via 112.1.1.2, 00:27:11, FastEthernet0/0

112.0.0.0/24 is subnetted, 1 subnets
C
112.1.1.0 is directly connected, FastEthernet0/0

配置后的R2路由表为
R2#show ip ro
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 23.1.1.3 to network 0.0.0.0


2.0.0.0/24 is subnetted, 1 subnets
C
2.2.2.0 is directly connected, Loopback0

*
23.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C
23.1.1.0/24 is directly connected, Serial1/1
D*
23.0.0.0/8 is a summary, 00:28:39, Null0
//由network 23.0.0.0产生

112.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C
112.1.1.0/24 is directly connected, FastEthernet0/0
D
112.0.0.0/8 is a summary, 00:28:39, Null0
S*
0.0.0.0/0 [1/0] via 23.1.1.3


R1#ping 3.3.3.3

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 64/96/180 ms

学习了……

不错，挺好

排版有点问题，看的不是很清楚!

结论是否：通过ip default-network命令通告的默认路由一定要在进程也要通告出来才可以出现在路由选择表中。