Optical Fiber Preps for High-Bandwidth Data Center


When it comes to enhancing the network capabilities of the data center, most of the attention goes to hardware like HBAs and NICs, or advanced protocols like 10 GbE and Fibre Channel.

But there is a fair amount of activity taking place on the infrastructure itself -- that is, the wiring and related technologies that provide the links between central systems, nodes and endpoints.

Much of the activity is taking place on the optical cable itself. New generations of product are hitting the channel in anticipation of 8 Gbps Fibre Channel, 10 Gbps Ethernet, 20 Gbps InfiniBand and beyond.

Canada's Zarlink Semiconductor, for example, just released the new ZLynx 4x10 Gbps active optical cable outfitted with quad small form factor (QSFP) terminations suitable for InfiniBand QDR environments. The cable is compatible with the company's existing lines of CX4, hybrid CX4-to-QSFP and QSFP products and features a new lightweight design that improves airflow in the data center to reduce cooling requirements.

For even higher data rates, Finisar Corp. has introduced the C.wire, a 150 Gb active optical cable that the company is targeting at storage, data center and HPC environments. The wire is based on the CXP form factor and can be used with InfiniBand, 100G Ethernet or proprietary interconnects. It transmits parallel 12x12.5 Gbps data bi-directionally using multimode fiber (MMF) ribbon cable, although the company also has a 12x10 Gbps version for InfiniBand 12xQDR and 100 GbE applications.

In the future, expect to see the power envelope of optical cabling to fall dramatically. GigOptix recently demonstrated a 100-meter, error-free 10 Gbps MMF link running at less than 81 mW per channel, which works out to about 8 mW per Gbps. The feat means GigOptix will soon be able to mount 12-channel links using SNAP12, CXP or 100Gbase-SR10 formats with less than 1W power dissipation, a six-fold improvement over current single power supply solutions. The demo featured off-the-shelf 850 nm O/E components and GigOptix' HXT/R4 multichannel VCSEL driver and receiver arrays.

Optical networks are also set to become more appliance-friendly with solutions like Napatech's NTBPE optical bypass adapter in the works. The device provides intelligent bypass and failover for in-line network appliances, providing a means to upgrade appliance functionality without disrupting network traffic. The unit provides up to four 1 Gbps or 10 Gbps ports that support applications like in-line network monitoring, measurement and security across two network connections. If either the adapter or the support server fails, the appliance will automatically switch to bypass mode to maintain connectivity. Bypass can also be triggered manually via software for scheduled maintenance and upgrades.

Clearly, optical cabling should be reserved for either long-haul connections or for high-bandwidth applications. For most run-of-the-mill enterprise environments, copper cabling should suffice. But as data protocols start to creep beyond the current 10 GbE/20 Gbps InfiniBand range into 40 Gbps, 100 Gbps and higher, expect optical infrastructure to play a larger and larger role in the data center.