Infiniband Gets New Life on Fiber

Arthur Cole

A new breed of optical networking technologies is finally allowing Infiniband to break free of the distance and bandwidth limitations that have made it primarily a short-range computer clustering solution.


The trend could put Infiniband on the fast track for a wider role in datacenter operations at a time when enterprises are increasingly forgoing heavier copper infrastructure in favor of lighter and more flexible fiber cabling.


Part of the movement toward fiber is the fact that it supports the 40Gbps Quad Data Rate (QDR) implementation of Infiniband at a time when 40 GbE solutions are still largely on the drawing board. Indeed, one of the chief limitations of Infiniband to date has been the fact that copper can support only up to the 20 Gbps Double Data Rate (DDR) format, but only to a distance of eight to 10 meters.


Luxtera Inc. has one of the newest systems on the market, the 40 Gb Blazar optical active cable (OAC), which extends QDR Infiniband up to 300 meters at a cost equivalent to current DDR solutions. The single-mode fiber is available in a pre-assembled solution that features four 10.5 Gb transmitters in a hermetically sealed laser, capable of reaching the 300-meter point without electronic dispersion compensation (EDC) technology.


Intel is another player in the optical cable game, having realized a number of years ago that copper was proving less and less effective with each successive boost in CPU performance. The company's Connects Cables solution currently features four independent paths capable of 5 Gbps, allowing 20 Gbps Infiniband up to 100 meters or so. Speed and accuracy are Intel's main advantages, providing a bit error rate of 10-15 and an optical/electrical conversion time of 275 picoseconds to deliver a maximum latency of 550 ps.


Also looking to get in on the action is Canada's Zarlink Semiconductor, which has devised the Zlynx system, an active optical cable assembly with integrated optical/electrical converters. The company recently received compliance verification from the Infiniband Trade Association for 20 Gbps transmission up to 100 meters. The system will feature a quad small form-factor pluggable (QSFP) transceiver for SDR and DDR Infiniband by the end of the year, with a QDR version available early next year.


It's always been a rule of thumb that the farther away you move from the CPU, the lower the data rate. And while that rule still holds, optical networks will likely be the key to bringing high-performance computing capabilities out of universities and research facilities and into the commercial enterprise.

Add Comment      Leave a comment on this blog post
Sep 7, 2007 4:22 AM Mark Mark  says:
Are you aware of Obsidian Research SDR Range Extenders (designed to 100,000 miles) called Longbows? Certainly this will open up the Enterprise market for IB. Reply

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