First Serial RapidIO Switch Arrives

April 14, 2005
Switch fabrics need switch chips—let the melee begin.

The steadfast wait for Serial RapidIO to move into high gear is over. Enter the Tsi586A from Tundra Semiconductor. The switch can be configured with 4x or 1x ports, and it will handle up to eight 4x ports and 16 1x ports or any mix in between. It also can be used to build more complex switches (see the figure). Pricing for the Tsi586A runs less than $99.

The Tsi586A is well-suited for switched backplanes, as well as for boards with multiple Serial RapidIO-based processors and peripherals. Such boards typically use a single chip. The Tsi586A additionally handles automatic speed negotiation. It supports hot-swapping, which is very useful in high-availability, rack-mounted systems too.

In addition, the chip imposes a low latency on traffic and improves performance with cut-through operation. As a result, data can stream through the switch without being fully buffered if there's no packet currently being sent through the designated output port. The chip also handles its own error statistics. The system can be configured via inline Serial RapidIO communication. Or, it can be configured via the I2C port or configuration pins.

Each port has its own serializer/deserializer (SERDES) set. The logical port can support a 4x Serial RapidIO connection or two 1x connections. Each port is programmable and can be individually configured and powered down. Traffic is full-duplex and nonblocking with hardware-based cyclic-redundancy-check (CDC) generation and checking on each packet of data.

SERIAL RapidIO SET TO SOAR Serial RapidIO has bounced around the news for ages. Its cousin, Parallel RapidIO, is already shipping, whereas Serial RapidIO stood by waiting for switches such as the Tundra Tsi586A. Test systems were constructed using FPGAs, but now more complex systems with a cheaper and faster alternative must be built.

Expect Serial RapidIO to take off upon the arrival of Tundra's chip. Other chip vendors are sure to follow in rapid-fire fashion. Specialized applications will keep Parallel RapidIO around, but the bulk of new designs will start with Serial RapidIO in place.

The other pieces to the puzzle include microprocessors and DSPs with built-in Serial RapidIO interfaces and switched backplanes. The latter are already here, employed by FPGA-based evaluation systems. Switches based on the Tundra chip and its competitors will replace them.

Backplane standards that use Serial RapidIO include PICMG 3.0 and PICMG 3.5 AdvancedTCA, AMC 4.0 (AdvancedTCA Mezzanine Card), VXS (VME Switched Serial), VITA 41 and VITA 46, and XMC (Switched Mezzanine Card). A typical AdvancedTCA chassis will need a 4x switch fabric that supports eight to 16 ports.

Finally, it appears to be the year of Serial RapidIO.


Performance: eight 4x or 16 1x Serial RapidIO links

Link speed: 1.25, 2.5, and 3.125 Gbits/s

Fabric throughput: 80 Gbits/s

Features: hot-swap, low-latency cut-through operation, head-of-line blocking prevention, error status and reporting

Power management: pin configuration, I2C, inline

Package: 27 by 27 mm, 675-ball, lead-free

Price: under $99

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