Networking - Networking Basics - Discussion

I can't understand the answer. Pat means port address translation. Then how many users can connect to global internet.

What the different between NAT and PAT ?

PAT-PORT ADDRESS TRANSLATION; NAT-NETWORK ADDRESS TRANSLATION. In my sense both are similar both share one ip address. In simple words the PAT is the NAT overloading where it uses one ip address for all clients to multiple ports. Whereas as a standard NAT is one-to one ip address relation.

Can anyone give brief description about NAT and PAT?

NAT:

Short for Network Address Translation, an Internet standard that enables a local-area network (LAN) to use one set of IP addresses for internal traffic and a second set of addresses for external traffic.

PAT:

Short for port address translation, a type of network address translation. During PAT, each computer on LAN is translated to the same IP address, but with a different port number assignment.

NAT(Network Address Translation):--> One ip one Port.
PAT(Port Address Translation) :--> One ip multiple port.

NAT not understand what is main difference between NAT and PAT?

Basic For NAT : With the explosion of the Internet and the increase in home networks and business networks, the number of available IP addresses is simply not enough. This is where NAT comes to the rescue. Network Address Translation allows a single device, such as a router, to act as an agent between the Internet (or "public network") and a local (or "private") network. This means that only a single, unique IP address is required to represent an entire group of computers.

NAT is used by a device and do mapping of an unregistered IP address to a registered IP address on a one-to-one basis.

NAT that maps multiple unregistered IP addresses to a single registered IP address by using different ports. This is known also as PAT (Port Address Translation).

Even I didnt get the difference between NAT and PAT. I know individual definitions but as far as difference is concerned...not clear yet. From Configuration point of view the difference while applying at router is : PAT uses an additional word i.e. overload.

Ex: ip nat inside Source list [access list number] pool [pool name] overload..........in PAT.

For NAT the command remains same but without overload.

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

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

Summarizing:

- If we have like 200 hosts in a company and have more than 2 addresses, we use NAT;

- If we have like 200 hosts in a company and have only 1 public address, we use NAT and PAT (if we have many internal hosts to a single public address it can cause problems).