Implementation of network address translation in cisco packet tracer

 Network address translation (NAT) is a method of remapping one IP address space into another by modifying network address information in the ip header of packets while they are in transit across a traffic routing device. The technique was originally used as a shortcut to avoid the need to readdress every host when a network was moved. It has become a popular and essential tool in conserving global address space in the face of IPv4 address exhaustion. One Internet-routable IP address of a NAT gateway can be used for an entire private network.

Fig1

Types of NAT:

Static NAT: In this, a single private IP address is mapped with single Public IP address, i.e., a private IP address is translated to a public IP address. It is used in Web hosting.

Dynamic NAT: In this type of NAT, multiple private IP address are mapped to a pool of public IP address. It is used when we know the number of fixed users wants to access the Internet at a given point of time.

Procedure:

1.      Drag and drop the network devices to create the above topology using interfaces.

2.      Assign IP Address to the devices as follows:

a.       PC0:  10.0.0.10

b.      PC1:   10.0.0.20

c.       PC3:   10.0.0.30

d.      ROUTER 0 SE 0/1/0 100.0.0.1

e.       ROUTER 0 GIG0/1   10.0.0.1

f.        ROUTER 1 SE0/1/0 100.0.0.2

g.      ROUTER 1 GIG0/1   192.168.1.1

h.      SERVER 0  192.168.1.10

3.      Assign network address to the Router in cli as follows:

·         Router 1:

Router#en

Router#config t

Router(config)#interface Gig0/0

Router(config-if)#ip address 10.0.0.1 255.0.0.0

Router(config-if)#no shutdown

Router(config-if)#exit

Router(config)#interface set0/1/0

Router(config-if)#ip address 100.0.0.2 255.0.0.0

Router(config-if)#no shutdown

Router(config-if)#exit

  

   Router 2:

Router#configure terminal

Router(config)#interface gig0/1

Router(config-if)#ip address 192.168.1.1 255.255.255.0

ROUTER(config-if)#no shutdown

ROUTER(config-if)#exit

ROUTER(config)#interface Set0/1/0

ROUTER(config-if)#ip address 100.0.0.2 255.0.0.0

ROUTER(config-if)#no shutdown

ROUTER(config-if)#exit

4. Configure Static NAT:

Static NAT configuration requires three steps: -

• Define IP address mapping
• Define inside local interface
• Define inside global interface
• Syntax:

Router(config)#ip nat inside source static [inside local ip address] [inside global IP address]

Router 1 NAT configuration:

Result:

Testing Static NAT Configuration:

Type following command in the command prompt.

Router#show ip nat translations

Pro Inside global Inside local Outside local Outside global

--- 50.0.0.10 10.0.0.10 --- ---

--- 50.0.0.20 10.0.0.20 --- ---

--- 50.0.0.30 10.0.0.30 --- ---