Configuration NAT on the Router

Configuration NAT of the Router Bjelovar in IT network

IT network with NAT

Use the following values to configure NAT services on BJELOVAR:

• 1- Configure NAT on the BJELOVAR router to translate the /16 inside host IP addresses to the /24 outside network address range.
• 2- Use PAT, so that all addresses are using only the IP addresses of through, with a subnet mask of
• 3- Create a static mapping of to BJELOVAR Fastethernet 0 interface of This will allow other routers to ping the Fastethernet 0 interface of BJELOVAR with the command ping

Bjelovar#configure terminal

// 1- Dynamic translation - define the Standard access list permiting the inside private addresses - those inside local/private addresses that are to be translated
// Access list (ACL) are used by NAT to select addresses for dynamic translation
// Defining default ACL that tells the router which local IP addresses will be allowed to translate (in this example, the network /16 done from Wilcard mask)

#access list access-list-number permit source-IP-address Wildcard-mask

Bjelovar(config)#access-list 1 permit

// 2- Dynamic translation - Define the pool of global/public addresses to be allocated as needed, (pool name is POOLNAME)
// Create "a pool" ie. Group's public IP address that will be used to translate the local IP address 'Overload'. Local IP addresses from network /16 can translate IP addresses from the POOL and that the IP addresses in the range of /24 to /24

#ip nat pool pool name start IP end IP netmask prefix-length

Bjelovar(config)#ip nat pool POOLNAME netmask

// 2a- Dynamic translation - Define the PAT translation, use the ip nat inside source command. This command, with the overload option, will create port address translation using the serial 0 IP address as the base:
// establish overload translation
// Establish dynamic source translation, specifying the access list defined in the prior step
// Establishes PAT - Overload translation criteria of ACL over POOL

# ip nat inside source list access-list-number pool pool-name overload

Bjelovar(config)#ip nat inside source list 1 pool POOLNAME overload

// 3- create static mapping of to allow other routers to ping the Fastethernet 0 interface of R1
// Create static NAT (mapping) IP address, which will be coded by public IP address - Setting this static NAT other routers will be able to ping the Fa0 the 'Bjelovar' router.

#ip nat inside source static local IP global IP

Bjelovar(config)#ip nat inside source static

Bjelovar(config)#interface fastethernet 0
Bjelovar(config-if)#ip nat inside
Bjelovar(config)#interface serial 0
Bjelovar(config-if)#ip nat outside

9.1. Bjelovar#show ip nat translations

Pro Inside global Inside local Outside local Outside global
--- --- ---

9.2. Bjelovar#show ip nat statistics

Total active translations: 0 (0 static, 0 dynamic; 0 extended)
Outside interfaces: Serial0
Inside interfaces: FastEthernet0
Hits: 5 Misses: 5
Expired translations: 5
Dynamic mappings:
-- Inside Source
Access list 1 interface refcount 0

9.3. Bjelovar#show running-config

Building configuration...
Version 12.1
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
hostname Bjelovar
enable secret 5 $sdf$6978yhg$jnb76sd
enable password cisco
ip subnet-zero
ip dhcp excluded-address
ip dhcp pool poolname
interface Serial0
ip address
bandwidth 64
encapsulation frame-relay ietf
frame-relay lmi-type ansi
frame-relay map ip 101 broadcast
ip nat outside
interface FastEthernet0
ip address
no ip directed-broadcast
bandwidth 100000
ip nat inside
ip nat inside source list 1 pool poolname
ip nat pool poolname netmask
ip nat inside source static
ip classless
no ip http server
access-list 1 permit
line con 0
transport input none
password cisco
line aux 0
line vty 0 4
password cisco
no scheduler allocate