一、实验要求

1，R6为ISP只能配置IP地址，R1-R5的环回为私有网段
2，R1/4/5为全连的MGRE结构，R1/2/3为星型的拓扑结构，R1为中心站点
3，所有私有网段可以互相通讯，私有网段使用OSPF完成。

二、实验思路

1.R1-R5配置ip，设置自己的私网环回

2.R6作为ISP路由器，除了配置接口ip外不需要其他的配置

3.R1-R5都做一个缺省到ISP ，使其能够成功访问公网

4.R1.R2.R3为星型拓扑：R1为中心，R2、R3为分支

5.R1.R4.R5为全连则互为邻居

6.私网互通且为OSPF --- 宣告路由
 

三、实验步骤

1.划分网络，配置IP，并配置缺省路由

r2：

[r2]inter g 0/0/0
[r2-GigabitEthernet0/0/0] ip add 20.0.0.2 24
Apr 14 2024 14:41:57-08:00 r2 %%01IFNET/4/LINK_STATE(l)[0]:The line protocol IP 
on the interface GigabitEthernet0/0/0 has entered the UP state. 
[r2-GigabitEthernet0/0/0]inter l 0
[r2-LoopBack0]ip add 192.168.2.1 24
[r2-LoopBack0]q
[r2]ip route-static 0.0.0.0 0 20.0.0.6

其余略

2.R1/4/5为全连的MGRE结构

r5：

[r5]inter tunnel 0/0/1
[r5-Tunnel0/0/1]ip add 192.168.6.5 24
[r5-Tunnel0/0/1]tunnel-protocol gre p2mp 
[r5-Tunnel0/0/1]source 50.0.0.5
Apr 14 2024 15:06:39-08:00 r5 %%01IFNET/4/LINK_STATE(l)[0]:The line protocol IP 
on the interface Tunnel0/0/1 has entered the UP state. 
[r5-Tunnel0/0/1]
[r5-Tunnel0/0/1]nhrp entry 192.168.6.1 10.0.0.1 register
Info: This peer protocol address conflicts with hub register peer protocol addre
ss. 
[r5-Tunnel0/0/1]nhrp entry 192.168.6.4 40.0.0.4 register

r1，r4略

3.R1.R2.R3为星型拓扑：R1为中心，R2、R3为分支

接口类型改为广播,R1开启伪广播

[r1-Tunnel0/0/1]nhrp entry multicast dynamic
 

[r2]inter tunnel 0/0/2
[r2-Tunnel0/0/2]ip add 192.168.7.2 24
[r2-Tunnel0/0/2]tunnel-protocol gre p2mp 
[r2-Tunnel0/0/2]souce 
[r2-Tunnel0/0/2]nhrp entry 192.168.7.1 11.0.0.1 register
[r2-Tunnel0/0/2]source GigabitEthernet 0/0/0
Apr 14 2024 15:16:03-08:00 r2 %%01IFNET/4/LINK_STATE(l)[0]:The line protocol IP 
on the interface Tunnel0/0/2 has entered the UP state. Please check whether system data has been changed, and save data in timeConfiguration console time out, please press any key to log on[r2-Tunnel0/0/2]ospf network-type broadcast 

4.私网互通且为OSPF --- 宣告路由

[r3]ospf router-id 3.3.3.3
[r3-ospf-1]a 0
[r3-ospf-1-area-0.0.0.0]net 192.168.3.1 0.0.0.0
[r3-ospf-1-area-0.0.0.0]net 192.168.7.3 0.0.0.0

其余相同