100Gbit/s networking systems and components using silicon photonics

2014-1-2 14:57:40

Mellanox Technologies said it will ship 100Gbit/s networking systems and components using silicon photonics late next year or in early 2015. The Infiniband specialist will compete with Cisco Systems, Intel, and the startups Luxtera and OneChip in a race to field the technology to make fast, dense switches and interconnects practical.

Carriers and datacenters are hungry for 100G links, but current optics technologies are too expensive, large, and hot for widespread use. Analysts say silicon photonics promise a tenfold cut in costs and rise in density, as well as a fivefold reduction in power. All the products will use four 25G serial lanes. Mellanox's offering will be the first using the 25G enhanced data rate Infiniband standard. The company's high-end products use the 14G FDR standard today.

In May, Mellanox acquired Kotura for its 100G photonic integrated circuits. In June, it bought IPtronics for chips embedded in connectors and cables used in high-speed links.

"With these two companies, we can drive 100G and make it as simple as 10G," Gilad Shainer, vice president of marketing for Mellanox, told us. By the end of this year, Mellanox expects to have a more exact date for the launch. "We are pretty much done with 100G designs and already started work on 200G products for release in 2016-2017."

Cisco is sampling 100G modules -- but not systems using them -- based on technology acquired with the startup Lightwire using the 100GBASE-LR4 standard. Cisco said in January that its parts may include 2.5-D stacks.

This fall, Intel is expected to sample 100G silicon photonics based on technology it has been developing in its labs for many years. Intel first discussed such plans in January.

The devices will be used in datacenters to link top-of-rack switches with computer racks beneath them. They will also be used in gear for carrier core networks.

"My sense is that [server] market does not need 100G until 2016-2017," Jag Bolaria, a senior analyst at the Linley Group in Mountain View, Calif., told us. By that time, PCI Express Gen 4 links may provide another alternative.

Experts such as Andy Bechtolsheim, founder of the switch vendor Arista Networks, have said silicon photonics will be key to driving a sluggish market for 100G links. Mellanox's Shainer took a more conservative view, even though its Kotura acquisition was one of the first to show 100G capabilities.

"Silicon photonics is a sexy topic, but it will be only a part of 100G, not everything," Shainer said. Mellanox's products will also support copper and more traditional optics options.

The copper version will have shorter reach than current 14G products that extend less than five meters, but he would not predict an exact length. As an optical alternative to silicon photonics, the company will use VCSELs from a source he would not name.

The Kotura approach uses wavelength division multiplexing; some others use parallel single-mode optics. All the competitors are using CMOS for silicon photonics, except the startup OneChip, which uses indium phosphide.

Intel hopes to gain an additional edge by integrating a high-speed interconnect into future server processors. The link will presumably provide unique features when coupled with Intel's silicon photonics.

Shainer said such an approach will force tradeoffs such as limiting the topology and applications of the link. "There will be clear reasons for a separate interconnect chip, [and] some customers prefer not to use an integrated SoC fabric."

Mellanox has carved out a growing piece of the high-performance networking business by expanding from chips and cards into full systems and designing products that use both Infiniband and Ethernet. Nevertheless, it has come under pressure as 100G and low-latency Ethernet standards have enabled systems that match Infiniband products.

In addition, much of the focus for big datacenters and carriers has turned to building networks that are simpler to manage using virtualization and software-defined networking. Much of that work is focused on Ethernet, rather than Infiniband. For its part, Mellanox has created an Ethernet initiative to drive open-source efforts and bolster interoperability of core Ethernet features such as routing and boot loaders.

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