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deterministic (Source NAT Next Gen Services)


Hierarchy Level


Configure deterministic NAT to ensure that the original internal source IPv4 or IPv6 address and port always map to the same post-NAT IPv4 address and block of ports. In addition, the reverse mapping of a given translated external IPv4 address and port are always mapped to the same internal IP address.

This eliminates the need for address translation logging.


block-size block-size

The number of ports in the port block.

  • Range: 1 to 64,512

  • Default: 256

host address address

The first usable pre-NAT subscriber address, which is used to perform the deterministic NAT mapping.


Include the translation of the lowest and highest IPv4 addresses (the network and broadcast addresses) in the source address range of a NAT rule. This does not apply to IPv6 source addresses.

Required Privilege Level

interface—To view this statement in the configuration.

interface-control—To add this statement to the configuration.

Release Information

Statement introduced in Junos OS Release 19.3R2.