CCNA Nat Sim Exam lab on GNS3 | ICND2 Lab

CCNA Nat Sim Exam lab on GNS3 | ICND2 Lab 

Question

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 192.168.2.1 to 192.168.2.14.

• 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 192.168.1.107 to 192.168.1.110 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:

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

Cloud:

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=192.168.2.1
Gatway= 192.168.2.2
You can learn how to configure IP address and Gateway of VPCS on gns3 from here.

Solution:

1.Configure serial f0/0 as NAT inside 

Router>enable 
Router#config t

Router(config)#hostname PE-router

PE-router(config)#interface fa0/0 

PE-router(config-if)#ip nat inside 
PE-router(config-if)#exit 

2.Configure serial s0/0 as NAT outside

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

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 192.168.1.107 192.168.1.110 netmask 255.255.255.248

Now create an access-list for private IP addresses and permit all hosts.

PE-router(config)#access-list 1 permit 192.168.2.0 0.0.0.15

Now apply this access-list with NAT, following command will pick up IP address from 192.168.2.1 to 192.168.2.14 and with map it to LIVEIP-POOL (200.200.200.105 to 200.200.200.110)

“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

Testing:

 Ping 192.168.1.1 or some internet address like 4.2.2.2 and then see the nat translations using "show ip nat translations"

PE-router# show ip nat tran