Network address translation
As traffic passes from the local network to the Internet, the source address in each packet is translated on the fly from a private address to the public address. If the IP address of pool are not free, then the packet will be dropped as only fixed number of private IP address can be translated to public addresses.
Suppose, if there is pool of 2 public IP addresses then only 2 private IP addresses can be translated at a given time. The computer receiving a packet that has undergone NAT establishes a connection to the port and IP address specified in the altered packet, oblivious to the fact that the supplied address is being translated analogous to using a post office box number.
Nat stands for network address translation
Once a system from outside the network has been allowed to access a computer within the network, the IP address is then translated from the router's address to the computer's unique address. Dynamic network address translation[ edit ] Dynamic NAT, just like static NAT, is not common in smaller networks but is found within larger corporations with complex networks. Only an external host that receives a packet from an internal host can send a packet back. A router with the NAT loopback feature detects that The originating host may perform Maximum transmission unit MTU path discovery to determine the packet size that can be transmitted without fragmentation, and then set the don't fragment DF bit in the appropriate packet header field. The packet is then forwarded over the inside network. Now that's efficient. However, this introduces problems with more sophisticated communications that have many interconnected packets, and thus is rarely used. This is generally used for Web hosting. That being said, using unique local addresses in combination with network prefix translation can achieve similar results.Thus avoiding the NAT and statefulness problems of Carrier Grade NAT, and also provides a transition mechanism for the deployment of native IPv6 at the same time with very little added complexity.
The obvious solution is to redesign the address format to allow for more possible addresses. Dynamic network address translation[ edit ] Dynamic NAT, just like static NAT, is not common in smaller networks but is found within larger corporations with complex networks.
When a reply returns to the router, it uses the connection tracking data it stored during the outbound phase to determine the private address on the internal network to which to forward the reply.
Phones that encrypt their signaling with IPsec encapsulate the port information within an encrypted packet, meaning that NA P T devices cannot access and translate the port. If this source port is already used, PAT assigns the first available port number starting from the beginning of the appropriate port group 0—, —, or — Thus, two-way communication is possible between hosts inside the LAN network via the public IP address.
For example, port 80 connects to the web server software and port 25 to a mail server's SMTP daemon. An IP address IP stands for Internet Protocol is a unique bit number that identifies the location of your computer on a network. This address is often used by the router that connects the computers to the Internet.