Glossary Updates12 new terms added to the glossaries · October 2, 2026, 22:44 CEST
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Glossary · Automation fundamentals, platforms and components

Multicast

Also known as: IP multicast

German: Multicast

In networking, multicast is the transmission of a message from one sender to a group of receivers at the same time, where the network delivers copies only to members that have joined the group.

  • Automation components

In one sentence

Multicast sends one message to a group of receivers at once; the network delivers copies only to members of the group.

Example

EtherNet/IP I/O connections can use multicast so that several controllers receive the same input data from one adapter.

How it applies

  • Engineering: Multicast is used by EtherNet/IP implicit messaging, PTP time synchronization, IEC 61850 GOOSE messages and service discovery. Switches with IGMP snooping keep multicast traffic from flooding the network.
  • Operation: Unmanaged multicast traffic can overload devices and networks; network design must account for it.
  • Documentation: State which multicast addresses and protocols a device uses and which switch settings are required. IT and OT teams need this information for network configuration and firewall rules.
  • Commissioning: Network analyzers help locate multicast storms and misconfigured switches during commissioning.

Multicast vs. broadcast vs. unicast

Unicast goes to one receiver, broadcast to all devices in a network segment, multicast to a subscribed group. Multicast saves bandwidth compared with repeated unicast but requires network support.

By knowledge.aitechdoc.world · Published September 26, 2026 · Last reviewed

Source: AI TechDoc Knowledge editorial definition, based on IP networking practice

Definitions follow the cited standards and specifications. Where a source is a copyrighted publication, such as an ISO, IEC or EN standard, the definition is a close paraphrase, not a verbatim quotation, so as not to infringe copyright. We recommend reading the original publication. The sections “How it applies” are editorial commentary by AI TechDoc Knowledge and are not part of any standard.

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