Nat Sim for ICND2 Practice lab on GNS3

Your company has 14 PCs those need to access the internet simultaneously. All the computers in the local area network are using the private IP addresses from to
  • Configure serial s0/0 as NAT outside
  • Configure serial f0/0 as NAT inside
  • You need to configure NAT (network address translation) on PE-router with 4 public IP addresses from to so that all the hosts can use internet at the same time.

Note: Since we are creating this lab on GNS3 therefore we are using private IP addresses i.e. 192.168.1.X for NAT translation instead of real Public IPs. Please keep in mind that in real scenario you must use Public IP addresses. 
For configuring this lab on GNS3 1.1 i have used the following devices:

IOS: c7200-jk9s-mz.124-13b.image
Router full configuration: PE-Router configuration

I have used cloud for internet connectivity with my laptop Ethernet interface, i also recommend you to use physical local area connection of your PC with gns3-cloud instead of wifi-adapter, you learn how to use cloud in GNS3 from here.

VPCS (Virtual-Host):
IP adress=
You can learn how to configure IP address and Gateway of VPCS on gns3 from here.


1.Configure serial f0/0 as NAT inside 

config t
Router(config)#hostname PE-router
PE-router(config)#interface fa0/0 
PE-router(config-if)#ip nat inside 

2.Configure serial s0/0 as NAT outside

PE-router(config)#interface s0/0 
ip nat outside 

3.Configure NAT ON Router:

In second step you need to configure pool of Public IP addresses, you can do it by using following commands:
PE-router(config)# ip nat pool LIVEIP-POOL netmask

Now create an access-list for private IP addresses and permit all hosts.
PE-router(config)#access-list 1 permit
Now apply this access-list with NAT, following command will pick up IP address from to and with map it to LIVEIP-POOL ( to
“Overload” keyword allows to map multiple IP addresses to a single registered IP address by using different ports.
PE-router(config)#ip nat inside source list 1 pool LIVEIP-POOL overload
Save all configurations;
PE-router#copy run start
 Ping or some internet address like and then see the nat translations using "show ip nat translations"
PE-router# show ip nat tran

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