1. 기본 네트워크 구성

ISP

conf t
	int g0/0
    ip add dhcp
    ip nat outside
    no sh
    
    int g1/0
    ip nat inside
    ip add 1.1.10.2 255.255.255.252
    no sh
    exit
    
    ip nat inside source list 1 int g0/0
    access-list 1 permit any

R1

conf t
	int g1/0
    ip add 1.1.10.1 255.255.255.252
    no sh
    
    int g2/0
    ip add 1.1.12.1 255.255.255.252
    no sh

R2

conf t
	int g2/0
    ip add 1.1.12.2 255.255.255.252
    no sh
    
    int g3/0
    ip add 1.1.13.2 255.255.255.252
    no sh

R3

conf t
	int g3/0
    ip add 1.1.13.1 255.255.255.252
    no sh
    
    int g0/0
    ip add 1.1.30.1 255.255.255.0
    no sh

PC1

ip 1.1.30.2/24 1.1.30.1

2. rip를 통해 pc에서 ping 8.8.8.8 성공

ISP

conf t
	router rip
    version 2
    no auto-summary
    net 1.0.0.0
    default-information originate

R1, R2, R3

conf t
	router rip
    version 2
    no auto-summary
    net 1.0.0.0

PC

ping 8.8.8.8 - success

3. 각 라우터에 loopback 정보 입력

R1

conf t
	int l0
    ip add 10.1.1.1 255.255.255.0
    
    int l1
    ip add 172.16.1.1 255.255.255.0
    
    int l2
    ip add 192.168.10.1 255.255.255.192

R2

conf t
	int l0
    ip add 10.2.2.2 255.255.255.0
    
    int l1
    ip add 172.16.2.1 255.255.255.0
    
    int l2
    ip add 192.168.10.65 255.255.255.192

R3

conf t
	int l0
    ip add 10.0.0.1 255.255.255.0
    int l1
    ip add 10.0.1.1 255.255.255.0
    int l2
    ip add 10.0.2.1 255.255.255.0
    int l3
    ip add 10.0.3.1 255.255.255.0
    
    int l4
    ip add 192.168.0.1 255.255.255.0
    int l5
    ip add 192.168.1.1 255.255.255.0
    
    int l6
    ip add 172.0.0.1 255.255.0.0
    int l7
    ip add 172.1.0.1 255.255.0.0

4. loopback을 rip network 연결하여 R1에서 ping 172.1.0.1 성공