Finisar brings serial active optical cable to 10G applications

NOVEMBER 12, 2007 By Stephen Hardy � An increasing number of companies have targeted active optical cables at the InfiniBand market. Finisar Corp. (search for Finisar) hopes to do the same for 10-Gigabit Ethernet server connectivity. Unlike the parallel optical InfiniBand cables, however, Finisar's new Laserwire family is a serial offering -- with a proprietary connector.

The Laserwire line consists of the cable, a high density electrical connector, and 10G SFP+ and XFP adapter modules for application where the proprietary connector isn't supported. According to Jan Meise, director of strategic marketing at Finisar, the company has aimed the new active cable at NIC-to-switch and LAN-on-motherboard applications in the data center, particularly in high-performance computing environments. These connections typically use copper cabling, either using CX-4 connectors or an RJ-45 in the case of 10GBase-T.

However, both copper-based approaches present problems to users, Meise says. In the case of the CX-4, distances are limited to 15 m and power would need to be provided to the CX-4 port -- assuming it's there in the first place. Port density also would be compromised. A 10GBase-T approach would minimize some of these headaches, but provide a few of its own. These would include significant power dissipation (current PHY samples require greater than 10 W, Meise says), increased latency, and added weight in comparison to Cat5e cabling.

The fiber-based Laserwire provides a superior alternative, Meise believes. The active optical cable would weigh less than the copper associated with the CX-4 and 10GBase-T alternatives -- 90% less than the CX-4 approach, Meise asserts. Its small connector size should enable 48-port 1U switch designs when using the proprietary connector as well. And it would require approximately half the board power consumption of 10GBase-T, he says.

Finisar plans to demonstrate the Laserwire this week at Supercomputing 07 in Reno in cooperation with Chelsio, Force10 Networks, Fujitsu Computer Products of America, Myricom, NetEffect, Neterion, and NetXen. The demonstrations will feature transmission distances of 30 m, but Meise says the product should support 100 m reaches.

These demonstrations will be adapter based. Meise concedes that the company faces a challenge in getting the industry to embrace a nonstandard connector. However, Meise believes the high-performance computing community is more open minded about adopting new technology than some other markets. Meanwhile, Finisar is in discussions with other companies that could serve as second sources for both the active optical cable as well as the connector.

Meise says he in encouraged by the response to the product so far, pointing to a quote from an executive at Force10 Networks that Finisar included in the press release announcing the product:

"As 10-gig servers become more prevalent in the data center, power and 10-gig interconnect cost became a significant challenge, as does connecting these servers in a way that allows organizations to optimize their computing power," said Stephen Garrison, vice president of marketing at Force10 Networks, one of the participants in the Laserwire demonstration at Supercomputing 07. "The Force10 S2410 provides high-density 10-Gigabit Ethernet connectivity that enables organizations to directly connect to 10-gig servers while Laserwire delivers the low power and low cost 'plug and play' interconnect that organizations need to efficiently utilize increased computing resources."

Meise says he expects to see deployment of the cables next year.

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