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160 Rockwell Automation Publication 1783-UM007I-EN-P - December 2017
Chapter 3 Configure Switch Features
Configuration Overview
To configure NAT, you create one or more unique NAT instances. A NAT
instance contains entries that define each address translation and other
configuration parameters.
The translations that you define depend on whether traffic is routed through a
Layer 3 switch or router or a Layer 2 switch.
If traffic is routed through a Layer 3 switch or router ( Figure 22 and Figure 23 ),
you define the following:
•
A private-to-public translation for each device on the private subnet that
communicates on the public subnet.
(1)
•
A gateway translation for the Layer 3 switch or router.
You do not need to configure NAT for all devices on the private subnet.
For example, you can choose to omit some devices from NAT to increase
security, decrease traffic, or conserve public address space. By default,
untranslated packets are dropped at the NAT boundary.
IMPORTANT Before you create NAT instances, configure all Smartport roles and VLANs.
IMPORTANT As a best practice, we recommend you route traffic through a Layer 3 switch
or router.
(1) Machines that communicate with each other within the same VLAN and subnet across a NAT boundary also require public-to-
private translations.