RapidIO: The Next Generation Communication Fabric For Embedded Application

11.4. MULTICASTING TRANSACTIONS IN RAPIDIO

The concept of duplicating a single message and sending it to multiple, selected destinations is known as 'multicast.' In many embedded processing systems, it is useful to have the capability to multicast data or messages. This can be accomplished by a variety of means in the system. For example the same data could be individually sent to all the selected targets sequentially. However, the most efficient implementation is to have hardware support present in the switch devices for the duplication of data packets or messages.

Within a RapidIO system, the ability to duplicate data packets or messages should scale with the number of end points in a system. Since the number of end points should scale with the number of switches in the system the multicast implementation for RapidIO mostly affects switches and only minimally impacts end points.

To further simplify the implementation complexity of multicast in RapidIO systems, the multicast functionality is limited to responseless write operations, specifically the NWRITE and SWRITE operations Implementing support for processing RapidIO logical layer response transactions within a switch device, which typically should not be aware of RapidIO logical layer protocols, is problematic and complex.

The ability to send a single message to multiple destinations can be implemented in a variety of ways, depending on system needs. However a standard approach is needed to simplify the task of developing ...