Providing Open Architecture High Availability Solutions

Rapid I/O

Rapid I/O (RIO) is a new interconnect technology that is being developed as a PCI replacement for

board and backplane interconnect. The RIO Trade Association controls and develops the

specifications. Thus, RIO is a open, publicly available standard to all trade association members.

Like InfiniBand, RIO is fabric based. Thus, switches are used to route data between end nodes.

Unlike InfiniBand message passing architecture, RIO uses a load/store base architecture analogous

to PCI. This in conjunction with its physical addressing makes RIO PCI software transparent; RIO

can work on existing operating systems with existing drivers as a direct PCI replacement without

requiring modifications to these software elements.

RIO uses low voltage differential signaling (LVDS). (LVDS is an IEEE electrical signaling

standard.) The clock frequency is 500 MHz with the data being double pumped. The data interface

widths are 8 bits, 16 bits, or 32 bits.

PCI-to-Fabric Bridging

Technologies are available to bridge switching fabrics to PCI buses. Several of these are

proprietary, but headed toward standardization. These systems typically have a fabric-based

topology that use point-to-point connections between nodes. Two types of devices are needed for

these types of systems: bridges and switches. The bridges provide a PCI bus on one side and a

fabric connection on the other side. Switches provide multiple connections to nodes, which are

usually bridges connected to the PCI bus. Packets are transported between the nodes via switches.

These type of systems can be made almost PCI software transparent, or they can be implemented as

transparent with enhanced features. While PCI transparency is good for legacy devices, it can

hinder future performance. Eventually, there will most likely be standards set in this area.