Multicast

Multicast facilitates efficient one-to-many data distribution across networks. A multicast source sends traffic to a multicast group, where members, like computers, IP phones or bus participants, receive the data simultaneously. It operates on the network layer of the OSI model. Its advantage is that messages can be transmitted simultaneously to several subscribers or to a closed group of subscribers without the data transmission rate used by the sender being multiplied by the number of receivers. With multicasting, the sender only requires the same data transmission rate as for a single receiver. In the case of packet-oriented data transmission, the data packets are duplicated at each individual distributor (router, switch or hub) on the route. Routing multicast packets involves creating a multicast tree, ensuring optimal traffic delivery to all group members.  

Several key protocols manage multicast operations: Internet Group Management Protocol (IGMP), Protocol Independent Multicast (PIM), Distance Vector Multicast Routing Protocol (DVMRP), Multicast Open Shortest Path First (MOSPF), and Multicast BGP (MBGP). IGMP, specific to IPv4, allows multiple devices to share a single IP address to collectively receive data. 

Multicast, broadcast, and unicast are distinct communication methods used for data transmission, each suited to specific scenarios. 

Unicast is a one-to-one communication model where data is sent from a single sender to a single recipient. This method is ideal for personalized or private exchanges, such as email or video calls, but becomes inefficient when addressing multiple recipients. For instance, streaming a video to 1,000 users via unicast would require the server to send 1,000 separate streams, consuming significant bandwidth and resources. 

In contrast, broadcast follows a one-to-all approach, delivering data to all devices within a network segment, whether they need it or not. While simple and effective for scenarios like network discovery, broadcast lacks selectivity and can overwhelm devices with irrelevant data. It is inefficient and unsuitable for large-scale communication across multiple networks. 

Multicast strikes a balance between these methods by enabling one-to-many communication, delivering a single data stream to multiple recipients who have explicitly opted into a multicast group. This approach is far more efficient than unicast for group communication and avoids the indiscriminate nature of broadcast. Multicast is particularly useful for live video streaming, online gaming, and real-time data feeds, as it minimizes redundancy and optimizes network resource usage. 

Multicast communication is highly relevant in industrial communication systems, particularly in fieldbus and industrial Ethernet networks, due to its efficiency and scalability in managing data exchange among multiple devices. In industrial environments, real-time data transmission is critical for coordinating processes, monitoring equipment, and ensuring operational reliability. Multicast enables one device, such as a controller, to send the same message simultaneously to multiple devices like sensors, actuators, or other controllers, without the need to send duplicate messages to each recipient individually. 

This capability is particularly beneficial in protocols like PROFINET, EtherNet/IP, and EtherCAT, where multicast is used to support time-critical communication, such as cyclic data updates or event notifications. For example, in factory automation, multicast allows programmable logic controllers (PLCs) to send synchronization signals or commands to all relevant devices in a production line, ensuring precise coordination of tasks. 

In fieldbus systems, multicast also reduces network traffic and latency by minimizing redundant data transmissions. This is crucial in applications requiring high determinism and low latency, such as motion control in robotics or energy systems. Furthermore, multicast's ability to enable group communication supports features like redundancy protocols and diagnostics, enhancing fault tolerance and system visibility in industrial networks. 

As a leading company in the field of industrial communication, Hilscher offers a broad portfolio of technologies and solutions for networking industrial environments. 

This includes a wide range of interface solutions for connecting sensors, actuators and controllers to industrial communication networks. The communication controllers of the netX family form the basis for this. The multi-protocol-capable SoCs can be integrated into automation components as required and their extensive chip peripherals enable powerful, efficient and flexible solutions. A protocol change is achieved by simply reloading Hilscher's own netX firmware. Building on this, the company also offers embedded modules and PC cards in all form factors in order to realise the netX communication interface with less integration effort. 

Hilscher also offers a comprehensive managed industrial IoT range under the netFIELD brand. This ranges from edge gateways as an application-oriented computer platform with integrated container management and the Edge OS Runtime running on it to the central cloud portal, via which the docker containers are deployed to the edge devices, through to turnkey containers for communication applications. 

Gateways and switches, devices for network diagnostics as well as masters and bridges for the wireless connection of IO-Link sensors round off the automation portfolio.