Installation guide

Network Infrastructure for EtherNet/IP™
Designing the Infrastructure
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It is important to keep in mind that everyone is working for the same team and toward the same goals.
This spirit of cooperation is a prerequisite to achieving an effective plant-floor-to-enterprise information
system. Business leaders also must realize that while engineers from both disciplines share the same
ideals—performance, speed, and security—they tend to employ different problem-solving methods to
achieve the same ends.
EtherNet/IP networks installed by control engineers will be carefully scrutinized by IT network specialists
before interconnecting them to business-level applications. For example, the IT department probably will
insist that any Ethernet infrastructure devices follow IT guidelines, policies, and procedures.
In addition, the IP addresses used on EtherNet/IP networks will need to be coordinated with an IT IP
address administrator. Network management policies will need to be changed to give IT operations’
support personnel access to Ethernet switch configuration parameters. The security threats posed by
devices on the EtherNet/IP networks will require gateway and/or firewall protection for the IT network.
Conversely, control engineers are likely to insist on “owning” the EtherNet/IP network switch hardware
installed on the plant floor. They will require that any piece of communication equipment conveying
control signal traffic be locally monitored, readily accessible, and replaceable by on-site maintenance
personnel. Control engineers may deem the IT support policies for critical production equipment to be not
sufficiently real-time for the uptime demands of the factory floor, and an IT department counter-proposal
to install redundant networks to ensure communication reliability may be deemed too expensive for the
return-on-investment metrics of the plant. Control engineers may complain that the IP address
administration policies and procedures are not workable for their plant-floor requirements, and may insist
on the ability to modify or expand control system networks without outside interference.
In one respect, IT security practices may be criticized for being too excessive for the control system
environment. Conversely, control system vendors are very cautious about operating system security
patches, and will want to verify that any operating system patches are compatible with control systems
before they are applied. Indiscriminate application of operating system and security patches has been
known to shut down some control system software that has not yet been checked out for operation with
the patches.
Who owns EtherNet/IP networks? This is not a simple question. EtherNet/IP networking issues span both
the information technologies’ and control systems’ organizational boundaries.
Having looked at isolated and non-isolated networks and provided detailed instructions for designing and
planning EtherNet/IP networks, as well as covering wiring issues, network topologies, and factors that
affect network performance, perhaps the most important issue is the “people factor.” Control engineers
and IT engineers need to work together on the top-down approach presented here to build an effective
plant-wide information system that gets the right data to those who need it wherever they are, and to get
the data to these destinations promptly and securely.