Installation guide

Network Infrastructure for EtherNet/IP™
6-65
Infrastructure Application Scenarios
6 Infrastructure Application Scenarios
Regardless of the specific application, all networks require a design that deals with
multicast traffic to meet the needs of real-time control.
EtherNet/IP supports both the time-critical (implicit) and non-time-critical (explicit) message transfer
services of CIP. With CIP, the exchange of time-critical messages (real-time control or I/O control) is
based on the producer-consumer model where a transmitting device produces data on the network, and
many receiving devices consume this data simultaneously. On EtherNet/IP, this functionality is provided
through IP multicast and Ethernet multicast mechanisms. The use of Ethernet for real-time control is
different from typical office and other non-time-critical applications.
In the office world, one of the primary network design objectives is to manage the traffic load on the
network. In the industrial world, the small, embedded control devices have modest CPU capability
compared to the office world’s PCs and workstations. Device CPU resources are needed to process each
broadcast and multicast message. While managing network bandwidth is always important, correct design
and setup of the Ethernet infrastructure must first protect the control devices from multicast and broadcast
floods that can slow or stop operation of these devices.
The recommendations in this section focus on addressing real-time control application needs. These
applications typically use the producer-consumer capabilities of EtherNet/IP, which are based on
multicast Ethernet communications. Monitoring, device configuration management, or explicit message
applications that use unicast communications do not need to follow the recommendations for multicast
traffic outlined in the following scenarios.
There is no single or standard approach to infrastructure implementation will provide the right balance of
performance, data connectivity, and installed cost for all applications. However, these scenarios address
the general application concerns of four typical types of industrial EtherNet/IP networks.
•
Isolated EtherNet/IP network with a single controller. An isolated EtherNet/IP
network interconnecting devices of a control system with a single controller.
•
Isolated EtherNet/IP network with multiple controllers. An isolated EtherNet/IP
network interconnecting devices of a control system with multiple controllers.
•
EtherNet/IP network connected to the enterprise network. An EtherNet/IP
network connected, via a gateway or equivalent, to the enterprise network. The control
system it serves can be of any complexity.
•
EtherNet/IP network integrated with the enterprise network. An EtherNet/IP
network that is fully integrated with the enterprise network. The control system it serves
can be of any complexity.