Flow Ctrl Tech Engineering

EtherNet/IP Network Engineering: Unicast vs Multicast CIP I/O & IGMP Snooping Rules

Prevent network flooding in Rockwell ControlLogix architectures: understanding Common Industrial Protocol (CIP), configuring IGMP Snooping queriers, and migrating to Unicast I/O.

  • Older EtherNet/IP devices broadcast cyclic I/O using multicast UDP, which unmanaged switches flood to every single port.
  • Flooded multicast traffic overwhelms 100Mbps ports on computers and HMIs, causing disconnection crashes.
  • Modern Rockwell systems default to Unicast CIP; always enable IGMP Snooping with an active querier if multicast is present.

Flow Ctrl Tech Engineering: Turnkey industrial automation, PLC programming, SCADA development, HMI, fieldbuses, and IIoT architectures. Contact our engineering center at [email protected] or phone +91 91110 91005.