Machine integration onto a plant’s network architecture can be difficult as OEM IP-address assignments rarely match those of the end-user network and network IP addresses are generally unknown until the machine is being installed – adding cost and time to the commissioning of the equipment, and delays moving that equipment into production.
The Allen-Bradley Stratix 5700 with Network Address Translation (NAT) is a hardware Layer 2 implementation that provides “wire speed” 1:1 translations ideal for automation applications where performance is critical.
Figure 1
What Is NAT?
Network Address Translation is a service that can translate a packet from one IP address to another IP address. NAT can be found either on a Layer 2 device or on a Layer 3 device. NAT can be understood easiest with the introduction of the concept of a private network and a public network (Figure 2)*. These two networks are separated by a boundary; a device that implements NAT is this boundary. NAT can take on multiple forms including one-to-many NAT and one-to-one NAT (our implementation).
Figure 2 – Concept Of Public And Private
Subnets With A NAT Device Separating
Figure 3 – One-To-Many NAT Example
One-to-many NAT is also known as Port Address Translation and allows one public IP address to be shared by many private IP addresses. This function is commonly found in consumer grade routers. A one-to-many NAT device contains a table that allows unique private host ports to be exposed on the single public IP address (Figure 3).
NAT Enabled Device
Stratix 5700
1783-NATR
Example Mapping
