Static And Dynamic Twice Nat Overview; Licensing Requirements For Static Nat - Cisco Nexus 3548 Configuration Manual

Static and Dynamic Twice NAT Overview

Static and Dynamic Twice NAT Overview

When both the source IP address and the destination IP address are translated as a single packet that goes
through a Network Address Translation (NAT) device, it is referred to as twice NAT. Twice NAT is supported
for static and dynamic translations.
Twice NAT allows you to configure two NAT translations (one inside and one outside) as part of a group of
translations. These translations can be applied to a single packet as it flows through a NAT device. When you
add two translations as part of a group, both the individual translations and the combined translation take
effect.
A NAT inside translation modifies the source IP address and port number when a packet flows from inside
to outside. It modifies the destination IP address and port number when the packet returns from outside to
inside. NAT outside translation modifies the source IP address and port number when the packet flows from
outside to inside, and it modifies the destination IP address and port number when the packet returns from
inside to outside.
Without twice NAT, only one of the translation rules is applied on a packet, either the source IP address and
port number or the destination IP address and port number.
Static NAT translations that belong to the same group are considered for twice NAT configuration. If a static
configuration does not have a configured group ID, the twice NAT configuration will not work. All inside
and outside NAT translations that belong to a single group that is identified by the group ID are paired to
form twice NAT translations.
Dynamic twice NAT translations dynamically select the source IP address and port number information from
pre-defined ip nat pool or interface overload configurations. Packet filtration is done by configuring ACLs,
and traffic must originate from the dynamic NAT translation rule direction such that source translation is done
by using dynamic NAT rules.
Dynamic twice NAT allows you to configure two NAT translations (one inside and one outside) as part of a
group of translations. One translation must be dynamic and other translation must be static. When these two
translations are part of a group of translations, both the translations can be applied on a single packet as it
goes through the NAT device either from inside to outside or from outside to inside.

Licensing Requirements for Static NAT

This table shows the licensing requirements for static NAT.
Product
Cisco
NX-OS
Cisco Nexus 3548 Switch NX-OS Interfaces Configuration Guide, Release 9x
96
License Requirement
Static NAT requires a LAN Base license and an Algo Boost license. For a complete explanation
of the Cisco NX-OS licensing scheme and how to obtain and apply licenses, see the Cisco
NX-OS Licensing Guide.
Make sure the LAN Base Services license is installed on the switch to enable Layer
Note
3 interfaces.
Configuring Static and Dynamic NAT Translation