MGRE环境下ospf

 根据题目要求如图标记

一、配置ip地址

[r1-GigabitEthernet0/0/0]ip address 116.0.0.1 24
[r1-GigabitEthernet0/0/1]ip address  16.0.0.1 24
[r1-LoopBack0]ip address  192.168.1.1 24

[r2-GigabitEthernet0/0/0]ip address  26.0.0.1 24
[r2-LoopBack0]ip address  192.168.2.1 24

[r3-GigabitEthernet0/0/0]ip address  36.0.0.1 24
[r3-LoopBack0]ip address  192.168.3.1 24

[r4-GigabitEthernet0/0/0]ip address  46.0.0.1 24
[r4-LoopBack0]ip address  192.168.4.1 24

[r5-GigabitEthernet0/0/0]ip address  56.0.0.1 24
[r5-LoopBack0]ip address  192.168.5.1 24

[ISP-GigabitEthernet0/0/1]ip address  16.0.0.2 24
[ISP-GigabitEthernet0/0/0]ip address  116.0.0.2 24
[ISP-GigabitEthernet0/0/2]ip address  26.0.0.2 24
[ISP-GigabitEthernet4/0/0]ip address  36.0.0.2 24
[ISP-GigabitEthernet3/0/0]ip address  46.0.0.2 24
[ISP-GigabitEthernet2/0/0]ip address  56.0.0.2 24
[ISP-LoopBack0]ip address  6.6.6.6 24

二、配置缺省路由，使得公网互通

[r1]ip route-static 0.0.0.0 0 16.0.0.2 
[r1]ip route-static 0.0.0.0 0 116.0.0.2

[r2]ip route-static 0.0.0.0 0 26.0.0.2

[r3]ip route-static 0.0.0.0 0 36.0.0.2

[r4]ip route-static 0.0.0.0 0 46.0.0.2

[r5]ip route-static 0.0.0.0 0 56.0.0.2

三、R1/R4/R5全连MGRE结构

[r1]interface Tunnel 0/0/0
[r1-Tunnel0/0/0]ip address 192.168.6.1 24
[r1-Tunnel0/0/0]tunnel-protocol gre p2mp 
[r1-Tunnel0/0/0]source 16.0.0.1
[r1-Tunnel0/0/0]nhrp network-id 100
[r1-Tunnel0/0/0]nhrp entry multicast dynamic 
[r1-Tunnel0/0/0]nhrp entry 192.168.6.2 46.0.0.1 register 
[r1-Tunnel0/0/0]nhrp entry 192.168.6.3 56.0.0.1 register

[r4]interface Tunnel 0/0/0
[r4-Tunnel0/0/0]ip address 192.168.6.2 24
[r4-Tunnel0/0/0]tunnel-protocol gre p2mp 
[r4-Tunnel0/0/0]source 46.0.0.1
[r4-Tunnel0/0/0]nhrp network-id 100
[r4-Tunnel0/0/0]nhrp entry multicast dynamic
[r4-Tunnel0/0/0]nhrp entry 192.168.6.1 16.0.0.1 register 
[r4-Tunnel0/0/0]nhrp entry 192.168.6.3 56.0.0.1 register

[r5]interface Tunnel 0/0/0
[r5-Tunnel0/0/0]ip address 192.168.6.3 24
[r5-Tunnel0/0/0]tunnel-protocol gre p2mp
[r5-Tunnel0/0/0]source 56.0.0.1 
[r5-Tunnel0/0/0]nhrp network-id 100
[r5-Tunnel0/0/0]nhrp entry multicast dynamic 
[r5-Tunnel0/0/0]nhrp entry 192.168.6.1 16.0.0.1 register 
[r5-Tunnel0/0/0]nhrp entry 192.168.6.2 46.0.0.1 register

四、R1/R2/R3的星型拓扑，以R1为中心

[r1]interface Tunnel 0/0/1
[r1-Tunnel0/0/1]ip address 192.168.7.1 24
[r1-Tunnel0/0/1]tunnel-protocol gre p2mp 
[r1-Tunnel0/0/1]source 116.0.0.1
[r1-Tunnel0/0/1]nhrp network-id 100
[r1-Tunnel0/0/1]nhrp entry multicast dynamic 

[r2]interface Tunnel 0/0/1
[r2-Tunnel0/0/1]ip address 192.168.7.2 24
[r2-Tunnel0/0/1]tunnel-protocol gre p2mp 
[r2-Tunnel0/0/1]source GigabitEthernet 0/0/0
[r2-Tunnel0/0/1]nhrp network-id 100
[r2-Tunnel0/0/1]nhrp entry 192.168.7.1 116.0.0.1 register 

[r3]interface Tunnel 0/0/1
[r3-Tunnel0/0/1]ip address 192.168.7.3 24
[r3-Tunnel0/0/1]tunnel-protocol gre p2mp 
[r3-Tunnel0/0/1]source GigabitEthernet 0/0/0
[r3-Tunnel0/0/1]nhrp network-id 100
[r3-Tunnel0/0/1]nhrp entry 192.168.7.1 116.0.0.1 register 

五、用ospf配置路由，使所有私网可以互相通信

[r1]ospf 1 router-id 1.1.1.1
[r1-ospf-1]area 0
[r1-ospf-1-area-0.0.0.0]network 192.168.1.0 0.0.0.255
[r1-ospf-1-area-0.0.0.0]network 192.168.6.0 0.0.0.255
[r1-ospf-1-area-0.0.0.0]network 192.168.7.0 0.0.0.255

[r2]ospf 1 router-id 2.2.2.2
[r2-ospf-1]area 0
[r2-ospf-1-area-0.0.0.0]network 192.168.7.0 0.0.0.255
[r2-ospf-1-area-0.0.0.0]network 192.168.2.0 0.0.0.255

[r3]ospf 1 router-id 3.3.3.3
[r3-ospf-1]area 0
[r3-ospf-1-area-0.0.0.0]network 192.168.3.0 0.0.0.255
[r3-ospf-1-area-0.0.0.0]network 192.168.7.0 0.0.0.255

[r4]ospf 1 router-id 4.4.4.4
[r4-ospf-1]area 0
[r4-ospf-1-area-0.0.0.0]network 192.168.4.0 0.0.0.255
[r4-ospf-1-area-0.0.0.0]network 192.168.6.0 0.0.0.255

[r5]ospf 1 router-id 5.5.5.5
[r5-ospf-1]area 0
[r5-ospf-1-area-0.0.0.0]network 192.168.5.0 0.0.0.255
[r5-ospf-1-area-0.0.0.0]network 192.168.6.0 0.0.0.255

此时在r1上ping其他路由只能ping通192.168.2.1，原因是因为跟MGRE环境下接口的网络类型有关
它是以P2P的工作方式进行的，P2P是点到点的工作方式，且P2P是不需要进行DR/BDR的选举的，它只能建立一个邻居，所以我们需要更改网络类型为breadcast。

六、更改网络类型

[r1]interface Tunnel 0/0/0
[r1-Tunnel0/0/0]ospf network-type broadcast 
[r1]interface Tunnel 0/0/1
[r1-Tunnel0/0/1]ospf network-type broadcast 

[r2]interface Tunnel 0/0/1
[r2-Tunnel0/0/1]ospf network-type broadcast 

[r3]interface Tunnel 0/0/1
[r3-Tunnel0/0/1]ospf network-type broadcast

[r4]interface Tunnel 0/0/0
[r4-Tunnel0/0/0]ospf network-type broadcast 

[r5]interface Tunnel 0/0/0
[r5-Tunnel0/0/0]ospf network-type broadcast 

此时发现只有ping192.168.2.1ping不同，查看路由表发现没有去往192.168.2.1的这条路由

查看R1的邻居表发现R2和R3的DR出现了分歧，都认为自己是DR，可以禁止R2和R3的DR选举权

 七、禁止R2和R3的DR选举权

[r2]interface Tunnel 0/0/1
[r2-Tunnel0/0/1]ospf dr-priority 0

[r3]interface Tunnel 0/0/1
[r3-Tunnel0/0/1]ospf dr-priority 0

八、测试能ping通