13.3 Supported NAT types

NNMi supports the following NAT protocols:

• Static NAT

  With static NAT, each internal IP address is always mapped to the same external IP address (each node has a pair of an internal address and an external address). This type of NAT allows accesses on the Internet while an unregistered (private) IP address is assigned to the internal host (such as a Web server).

• Dynamic NAT

  Dynamic NAT is a scheme that enables the binding of external and internal addresses to be changed at each session. An internal IP address is mapped to a public IP address that is obtained from a pool of available registered (public) IP addresses. Normally, a table of registered IP addresses is maintained within the NAT router in the network. When an access from an internal IP address to the Internet is requested, the router selects from the table another internal IP address that is available.

• Dynamic port address translation (dynamic PAT) (also called a network address and port translation (NAPT))

  Dynamic PAT is a type of NAT that translates not only IP addresses but also port numbers. If both addresses and port numbers are translated, multiple internal addresses can be used to communicate on the Internet concurrently using a single external address.

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