Rockwell Automation 1734-AENTR EtherNet/IP Network Configuration User Manual - Manual (Page 144)

144 Rockwell Automation Publication ENET-UM001L-EN-P - March 2014
Chapter 10 Troubleshoot an EtherNet/IP Communication Module with Diagnostic Web Pages
144 Rockwell Automation Publication ENET-UM001L-EN-P - March 2014
Chapter 10 Troubleshoot an EtherNet/IP Communication Module with Diagnostic Web Pages
Internet Group Multicast Protocol
EtherNet/IP implicit (I/O) messaging mostly uses IP multicasting to distribute
I/O control data, which is consistent with the CIP produced/consumer model.
Most switches retransmit multicast packets and broadcast packets to all ports.
IGMP snooping constrains the flooding of multicast traffic by dynamically
configuring switch ports so that multicast traffic is forwarded only to ports
associated with a particular IP multicast group. This also helps minimize the
CPU utilization rate.
Switches that support IGMP snooping learn which ports have devices that are
part of a particular multicast group and only forward the multicast packets to the
ports that are part of the multicast group.
IMPORTANT Not all switches support the IGMP snooping querier function, that is,
snooping. Those that do not support IGMP snooping querier require a
router. For switches that do support IGMP snooping, you can configure
them to conduct the polling.