Reply To: When to NAT

#3553
AdminFred Graham
Keymaster
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Hi Jonathan,

Traffic containment is definitely one advantage of using NAT configurations to isolate your “work-cell traffic”. The other advantage, as you mention, is IP address reusability. Virtually everything coming onto the production floor these days is an IP-based device, from PLCs, to HMIs, to “Smart” IO blocks, to Servo drives, and the list goes on and on which will quickly eat-up IP addresses on any subnet.

NAT provides a mechanism for controlled access, security, isolation and as you mention IP-address reusability. The latter becomes very useful specifically for dealing with outside OEMs and standards. Your controls engineers can now write a standard around the addressing convention for automation devices coming into your facility.

For example, you can standardize things like what address your PLCs, HMIs etc:

PLCs – 192.168.1.10 – .19

HMIs – 192.168.1.20 – .29

Drives – 192.168.1.30 – .39

You get the picture. This becomes very easy now from a maintainability stand-point and again it standardizes addressing schemes. There are of course a whole list of other advantages with going with managed switches in the work zone, remote management, traffic analysis, DHCP persistance, automatic DHCP assignment and all things I’m sure you’re very aware of.

This is a good thread and hopefully one that will get some good conversation going.

-Fred