CCNP实验---Eigrp default-network

当Eigrp路由连接一个外部网络时,可以通告一条静态的默认路由到EIGRP中去.即当做边界或称为”网关”,发布时,只能发主类网段。

 

R1:
interface Loopback0
 ip address 1.1.1.1 255.255.255.0
!
interface FastEthernet0/0
 ip address 10.1.1.1 255.255.255.0

 duplex auto
 speed auto

router eigrp 100
 network 1.1.1.0 0.0.0.255
 network 10.1.1.0 0.0.0.255
 no auto-summary
!

 

R2:
interface Loopback0
 ip address 172.16.1.1 255.255.255.0
!
interface FastEthernet0/0
 ip address 10.1.1.2 255.255.255.0
 duplex auto
 speed auto
!
router eigrp 100
 network 10.1.1.0 0.0.0.255
 network 172.16.1.0 0.0.0.255
 no auto-summary

ip default-network 172.16.0.0
ip route 172.16.0.0 255.255.0.0 172.16.1.2

 

查看R2的路由表：
R2#show ip route
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 172.16.1.2 to network 172.16.0.0

     1.0.0.0/24 is subnetted, 1 subnets
D       1.1.1.0 [90/156160] via 10.1.1.1, 00:08:16, FastEthernet0/0
 *   172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
S*      172.16.0.0/16 [1/0] via 172.16.1.2  //产生了一条静态默认路由,经过172.16.1.2
C       172.16.1.0/24 is directly connected, Loopback0
     10.0.0.0/24 is subnetted, 1 subnets
C       10.1.1.0 is directly connected, FastEthernet0/0

 

查看R1的路由表:
R1#show ip route
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 10.1.1.2 to network 172.16.0.0

     1.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C       1.1.1.0/24 is directly connected, Loopback0
D       1.0.0.0/8 is a summary, 00:01:17, Null0
D*   172.16.0.0/16 [90/156160] via 10.1.1.2, 00:00:09, FastEthernet0/0 //所有到172.16.0.0的网段都会发到F1/0接口上.直到达到路由器R2,即边界路由器
     10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C       10.1.1.0/30 is directly connected, FastEthernet0/0
D       10.0.0.0/8 is a summary, 00:01:17, Null0

 

如果在R2上不发布一个主类网络,如下:
R2(config)#no ip default-network 172.16.0.0
R2(config)#ip default-network 172.16.1.0 //把172.16.0.0 换成172.16.1.0

 

R1路由表显示如下:
R1#clear ip route *
R1#sh ip route
Gateway of last resort is not set
     1.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C       1.1.1.0/24 is directly connected, Loopback0
D       1.0.0.0/8 is a summary, 00:05:53, Null0
D    172.16.0.0/16 [90/156160] via 10.1.1.2, 00:01:58, FastEthernet0/0 //从EIGRP学来的默认路由已经消失
     10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C       10.1.1.0/30 is directly connected, FastEthernet0/0
D       10.0.0.0/8 is a summary, 00:05:53, Null0