Experimental requirements
1. R5 is an ISP and can only configure IP addresses; all its interfaces are configured as public IP addresses
2. PAP authentication is used between R1 and R5, R5 is the main authenticator; PPP chap authentication is used between R2 and R5, and
R5 is the main authenticator; HDLC encapsulation is used between R3 and R5
3. R1/2/3 build an MGRE environment, R1 is the central site; R1/4 is point-to-point GRE
4. The entire private network is reachable based on RIP
5. When all routers are based on the loopback private address as the source IP, they can access the R5 loopback normally
/
[r1]ip route=s
[r1]ip route-
[r1]ip route-static 0.0.0.0 0 15.1.1.2
[r2]ip route-s
[r2]ip route-static 0.0.0.0 0 25.1.1.1
[r2]
[r3]ip route-s
[r3]ip route-static 0.0.0.0 0 35.1.1.1
[r3]
[r4]ip route-s
[r4]ip route-static 0.0.0.0 0 45.1.1.1
[r4]
