Installation guide

Network Infrastructure for EtherNet/IP™
6-69
Infrastructure Application Scenarios
When using unmanaged switches, follow these guidelines:
Calculate or test the maximum multicast traffic load for each device.
For each device, ask the vendor for the maximum unwanted multicast packets per second rate that
the device can withstand while maintaining the desired RPI rate. Be sure to use the configuration with the
largest I/O count or most time-critical configuration. If the vendor cannot provide this information, refer
to the alternative traffic-management approaches presented below.
For each device connected by one or more unmanaged (non IGMP snooping) switches, add all the rates
together to determine the total multicast traffic in the
multicast domain, then add in any significant
broadcast traffic from application or network management software, and reduce the total by 5% for a
design buffer. Note that splitting the devices between different unmanaged switches makes no difference
in the total multicast domain traffic load as depicted in Figure 6-2.
Figure 6-2 Adding Unmanaged Switches Does Not Reduce the Size of a Multicast Domain.