Solution:

EtherNet/IP is a multivendor Industrial Ethernet technology managed by ODVA. The EtherNet/IP infrastructure guidelines require switches with IGMP snooping and IGMP query functions in all EtherNet/IP applications for general use or large-scale control enterprise and networking. Under the ODVA standard, a very small, isolated system with a low device count can use an unmanaged switch. However, the standard also clearly specifies that designers must either precalculate the total multicast traffic to which each unmanaged switch will be exposed or test the configuration in advance. EtherNet/IP devices can generate a great deal of multicast traffic. A multicast packet is a message addressed to a group of nodes. It is necessary to limit which end devices receive the traffic to avoid overloading them and causing them to fail. When a switch without IGMP snooping receives multicast messages, it floods all ports, potentially overloading end devices and other network switches. A switch with IGMP snooping, however, forwards multicast messages to only the devices that request the traffic. When an EtherNet/IP device wants to consume multicast data, it will transmit an IGMP join message. All IGMP snooping switches receive these join messages. The switch then snoops on the join messages as they pass to determine which ports will receive the multicast data. This restricts the multicast data to only the ports and connected end devices that expect and can handle the traffic.