RapidIO: The Next Generation Communication Fabric For Embedded Application

12.6. USING DATA STREAMING

Data streaming can be applied in a variety of different ways. The critical design issues revolve around the interfaces into and out of the RapidIO fabric. In telecommunications equipment, there are a wide variety of interconnect standards (SPI-3, SPI-4, UTOPIA, GMII, etc.). These standards are primarily focused on interfacing to the external communications networks. Standards for internal communications between chips and boards within a system have not existed up to this point. RapidIO is the first standard to be developed to specifically address this internal chip-to-chip and board-to-board communications requirement. In this role RapidIO can also form a common in-system fabric or interconnect for a wide variety of protocol internetworking applications.

When using the RapidIO data streaming logical layer transactions for protocol inter-networking, the first design decision will be how to use the virtual stream ID. The use of the VSID will vary according to the protocol that is being transported across a RapidIO system. An ATM application, for example, might use a RapidIO to UTOPIA bridge. The UTOPIA bus supports a number of physical devices on the same bus, these physical devices are addressed by the UTOPIA bus. The StreamID may be used as a subport address that translates to the physical UTOPIA address. If multiple UTOPIA ports are supported, the StreamID may be used to select UTOPIA interfaces. When the source examines the VPI/VCI fields for scheduling ...