What is the difference between NAT and PAT ?

Network Address Translation (NAT) and Port Address Translation (PAT) both map IP addresses on an internal network to IP addresses on an external network. Which method of address translation you use depends on the types of networks that you are translating and the number of available IP addresses that you have.

If you are connecting a site in the10.10.10.0 network to a site in the10.10.20.0 network, you could use NAT to translate10.10.10.0 IP addresses to available10.10.20.0 IP addresses so that hosts on the10.10.10.0 network can access data and use network resources on the10.10.20.0 network. However, for this scenario to work, you must have an address pool that contains enough available IP addresses on the10.10.20.0 network to accommodate every host on the10.10.10.0 network, because NAT requires a one-to-one relationship when translating IP addresses.

PAT attempts to use the original source port number of the internal host to form a unique, registered IP address and port number combination. For example, two hosts that have been assigned the IP addresses10.10.10.100 and10.10.10.101, respectively, could send traffic to and receive traffic from the Internet by using the single public IP address123.45.67.89. If that port number is already allocated, PAT searches for an available alternate source port number. Therefore, the host at IP address10.10.10.100 could access the Internet by using the public IP address and source port combination of123.45.67.89:10000. Meanwhile, the host at IP address10.10.10.101 could access the Internet by using the IP address and source port combination of123.45.67.89:10001.

If you are connecting a site in the10.10.10.0 network to the Internet, you must translate host IPs on that network to a registered IP address that is routable over the Internet. In order to use traditional NAT in this scenario, you would need to purchase a registered IP address for each host on your internal network. Alternatively, you could use PAT to translate all the IP addresses on the internal network to a single, shared IP address that connects to the Internet. PAT, which is also known as NAT overloading, uses16-bit source port numbers to map and track traffic between an internal host and the Internet.

Difference between NAT and PAT is the Addresses whose IP's are getting translated do not change their Ports in NAT whereas it does in PAT.

To brief you more, there are four types namely Dynamic NAT, Dynamic PAT, Static NAT, Static PAT

Dynamic NAT:- A range of IP's in your LAN Network will get translated to a pool of IP addresses that you define on the Outside Interface of your device.

Dynamic PAT:-  A range of IP's in your LAN Network will get translated to a single IP address. In order to differentiate between different IP addresses on the inside network, the NAT Device will change the Source Port of the LAN IPs and maintain in its NAT Table these mappings.

Static NAT:-  One to One Translation, One IP on the inside network will get translated to a routable IP on the outside network,

Static PAT:- This is tricky, consider this, a web server on the inside LAN network running on port443 has to be accessed on the outside network using port8080. This is where Static PAT comes into Picture. The web server's443 port will actually be accessible using port8080 if appropriate rules and ACL's are in place. 

Hope this helps!!!

NAT has different types. PAT is one of NAT types. PAT also known as NAT Overload.

NAT is Network Address Translation. It translates one IP into another IP address. For example, outgoing IP address10.0.0.1 gets translated to194.90.1.5 so it can be routed over the Internet.PAT is port address translation. It translates a port into another port. For example, incoming to port80 gets translated to port443

PAT Use Port number to distingish the device on the internal network.

NAT and PAT both use to allow a lot of device that have Private IP to use one Public IP to surf the internet

NAT is a protocol that translats inside addresses (private address) into global inside address (public ips)

PAT, is the same thing as NAT. The difference is, insted of translating ip's, PAT traslate into ports.

Il existe plusieurs types de translations

NAT statique : A exactement une adresse IP local correspond

exactement une adresse IP globale

NAT dynamique :

A plusieurs adresses IP locales correspondent plusieurs adresses IP

globales. Dans ce cas, on parle de pool d'adresses IP publiques

disponibles pour le NAT

Si qu'une seule adresse IP publique est disponible, dans ce cas, on parle

de Network Address Port Translation (NAPT) ou Port Address Translation

(PAT)

PAT : A plusieurs adresses IP locales correspondent une seule

adresse IP globale

Le suivi de la connexion se fait alors par l'utilisation de numéro de port

NAT is a protocol that translats inside addresses (private address) into global inside address (public ips). Its developed to hold the shortage of IPv4. It allow to have thousans of hosts with private ip address to be translated in public addresses.

PAT, is the same thing as NAT. The difference is, insted of translating ip's, PAT traslate into ports. Its ensure a company that have ONLY one public ip address to communicate with external hosts.

NAT is network address translation

PAT is port address translation

We can publish our internal ip to publich network through NAT

We can publish one of the port from internal to external network

Network Address Translation (NAT) and Port Address Translation (PAT) both map IP addresses on an internal network to IP addresses on an external network. Which method of address translation you use depends on the types of networks that you are translating and the number of available IP addresses that you have.