Efficient 100G, Powered by Photonic Integrated Circuits

The continued growth of optical backbone bandwidth, driven by video, mobility, and inter-datacenter traffic , means that network operators around the globe are considering 100G transmission technologies. But not all 100G is created equal: different implementations can have dramatically different implications on network economics. In fact, conventional 100G DWDM technology, implemented in muxponders using numerous discrete optical components, has two significant flaws: the first is a “muxponder tax”—an inefficient use of network bandwidth which negates some of the bandwidth-expanding capabilities of 100G waves. The second is an increase in space and power, and a loss of reliability, which stems from the manual interconnection of numerous optical components.

100G Waves and the Muxponder Tax

100G waves are needed in the network core to support an increase in bandwidth per fiber—from between 800G to 1.6T using 10G waves, to about 8T using 100G waves. But a close look at the services being carried by those 100G waves—in other words at the individual circuits being carried over the bandwidth created by 100G waves—shows that most services over the next four years will continue to be 10G and below. This is in part due to the phenomenal success of 10GbE in driving down cost per bit of physical interconnect, and is in part due to the highly-meshed nature of many real world networks.

Conventional DWDM systems carry 10G and smaller services over 100G waves using muxponders. Muxponders multiplex ten 10G signals into 100G wavelengths, effectively binding them together, such that all services must share the same end points as the muxponder wavelength. This architecture is efficient for simple point to point networks, but in real world mesh networks, muxponders tend to strand bits of bandwidth as the network grows. The fraction stranded can be termed a “muxponder tax” because it represents excess cost which does not tie to new revenue—it is effectively an economic loss inside the network. The size of the tax depends on network topology and traffic load, but it is easy to model realistic networks which incur a tax of nearly 50%! In other words, some muxponder-based networks, engineered for 8T per fiber using 100G, will only achieve 4T per fiber of useful bandwidth, while the other 4T is wasted to the muxponder tax.

Infinera’s 100G implementation, which takes advantage of our unique “Bandwidth Virtualization” architecture, eliminates the muxponder tax because we don’t use muxponders. Instead, services benefit from OTN-based switching and grooming throughout the core to wring maximum effiency out of 100G waves. Please see our Muxponder Tax whitepaper to learn more.

PIC-based 100G Coherent: Space & Power Efficiency + High Reliability

In addition to bandwidth efficiency, Infinera’s PIC-based implementation of 100G also results in space and power efficiency, plus excellent reliability. Infinera’s new 5x100G PM-QPSK photonic integrated circuits include around 600 optical functions on two small chips, a transmitter and receiver. When packaged, our 5x100G transmitter and receiver modules are about the size of an iPhone. This represents a dramatic improvement in density compared to conventional discrete components. At the same time, photonic integration eliminates hundreds of fiber couplings between chips. Fiber couplings are the number one cause of failure in optical components, and by eliminating these potential failure points, Infinera’s PICs bring optical layer reliability to a new level. Infinera’s first generation photonic integrated circuits, first shipped commercially in 2005, have now logged well over 300 million hours of operation in the field, without a single PIC failure.

Infinera’s implementation of 100G coherent transmission, using photonic integrated circuits coupled with Bandwidth Virtualization, results in superior bandwidth efficiency, space and power efficiency, and high reliability. Let us tell you more about it. Please click here to contact your local Infinera sales team, and be sure to check out the related whitepapers in the upper right corner. Also, we invite you to attend Light Reading’s December 1 webinar on 100G technologies. Visit http://www.lightreading.com/100G/ for more info.