scenario: Suppose your company buys a company . Now your management want you to connect the new company network with the exiting company network. Now you have got a very serious problem. one of your network is overlapping with the new company network. How to go about it. Find the network diagram below. suppose SITEA is your company. SITE A already connected with SITEB.Your new company is SITEC. SITEB & SITEC having overlapping network i.e 10.10.10.0/24. I have created NAT on SITEC router & the problem get resloved. Find the router configuration below. You can simulated the same scenario on GNS3 & check yourself.
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname SITEA
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
ip cef
!
!
!
!
no ip domain lookup
!
!
interface Loopback0
ip address 172.29.55.1 255.255.255.0
!
interface FastEthernet0/0
ip address 2.2.2.2 255.255.255.0
duplex auto
speed auto
!
interface FastEthernet0/1
ip address 3.3.3.2 255.255.255.0
duplex auto
speed auto
!
ip forward-protocol nd
ip route 10.10.10.0 255.255.255.0 3.3.3.1
ip route 192.168.1.0 255.255.255.0 2.2.2.1
!
no ip http server
no ip http secure-server
!
!
!
!
control-plane
!
!
line con 0
exec-timeout 0 0
logging synchronous
line aux 0
line vty 0 4
password cisco
login
!
!
end
SITEB
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname SITEB
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
ip cef
!
!
!
!
no ip domain lookup
!
!
!
interface Loopback0
ip address 10.10.10.1 255.255.255.0
!
interface FastEthernet0/0
ip address 3.3.3.1 255.255.255.0
duplex auto
speed auto
!
interface FastEthernet0/1
no ip address
shutdown
duplex auto
speed auto
!
ip forward-protocol nd
ip route 172.29.55.0 255.255.255.0 3.3.3.2
!
no ip http server
no ip http secure-server
!
!
!
!
control-plane
!
!
line con 0
exec-timeout 0 0
logging synchronous
line aux 0
line vty 0 4
!
!
end
SITEC
!
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname SMP
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
ip cef
!
!
!
!
no ip domain lookup
!
!
interface Loopback0
no ip address
ip nat inside
!
interface FastEthernet0/0
ip address 2.2.2.1 255.255.255.0
ip nat outside
speed 100
full-duplex
!
interface FastEthernet0/1
ip address 10.10.10.1 255.255.255.0
ip nat inside
duplex auto
speed auto
!
ip forward-protocol nd
ip route 172.29.55.0 255.255.255.0 2.2.2.2
!
no ip http server
no ip http secure-server
ip nat inside source static network 10.10.10.0 192.168.1.0 /24
!
access-list 50 permit 10.10.10.0 0.0.0.255
!
!
control-plane
!
!
line con 0
exec-timeout 0 0
logging synchronous
line aux 0
line vty 0 4
!
!
end
R5
!
!
version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R5
!
boot-start-marker
boot-end-marker
!
!
memory-size iomem 15
no aaa new-model
ip subnet-zero
ip cef
!
!
no ip domain lookup
!
!
!
interface FastEthernet0/0
ip address 10.10.10.20 255.255.255.0
speed 100
full-duplex
!
interface FastEthernet0/1
no ip address
shutdown
duplex auto
speed auto
!
no ip http server
ip classless
ip route 0.0.0.0 0.0.0.0 10.10.10.1
!
!
!
line con 0
exec-timeout 0 0
logging synchronous
line aux 0
line vty 0 4
password cisco
login
!
!
end
On SITEC router Check by excute the following command.
SITEC#sh ip nat translations
Pro Inside global Inside local Outside local Outside global
--- 192.168.1.1 10.10.10.1 --- ---
--- 192.168.1.2 10.10.10.2 --- ---
--- 192.168.1.20 10.10.10.20 --- ---
--- 192.168.1.0 10.10.10.0 --- ---
Cheers
