Installation guide

Network Infrastructure for EtherNet/IP™
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Infrastructure Application Scenarios
multicast messaging. Disabling multicast messages allows the use of unmanaged
switches. This is most effective for systems with one consumer.
In the systems described in these examples, a certain amount of the workstation’s and remote I/O devices’
computing power is used to filter the unwanted traffic. If the control engineer concludes that unwanted
multicast traffic affects the performance of these devices and, consequently system performance, then one
of the following recommendations may be considered:
Certain types of devices, such as PCs/workstations, can be more sensitive to unwanted multicast traffic. If
only workstation performance is affected, the controller should be connected via a separate switch as
shown in Figure 6-4. IGMP snooping need not be activated in any of these switches.
Figure 6-4 Isolated Network with One Controller and a Separate Network for HMI.
If both workstation and remote I/O performance is affected, a switch with IGMP snooping should be
used. The switch with IGMP snooping forwards IP multicast packets to consumer ports only. In isolated
multi-switch networks, one switch with the IGMP query function is needed, and the other switches need
to support the IGMP snooping function.
6.2.2 Systems with High I/O Count
Isolated systems with high producer device counts (i.e., I/O, drives, sensors, etc.), a large number of CIP
connections, and low RPI rates require the use of managed switches for implicit-messaging-based I/O
control applications. Larger non-time-critical applications (such as monitoring systems) with RPI rates
over 70 ms may be capable of using combinations of managed and unmanaged switches. Use the
guidelines in 6.2.1.1 Use of Unmanaged Switches to determine the potential for multicast overloads. As
systems grow larger, the need for web or SNMP diagnostics can considerably reduce initial system startup
times, and provide port-based traffic statistics to help optimize overall system performance. In addition,
as systems grow in complexity and size, the need for network redundancy often grows as well.
8-port Switch
Producer 1
Programmable
Controller
Workstation
8-port Switch 1 8-port Switch 4
Producer 6 Producer 19 Producer 24
Switch