Interconnected Blog

Interconnected Blog

An Open Ecosystem for Co-Packaged Optics

The pace of bandwidth growth isn’t slowing down with each generation drawing more power than the last. To address this dynamic, the industry needs to move to co-packaged optics (CPO). Today we are announcing a collaboration between Cisco and Inphi to drive an open ecosystem around the technology.

Increasing network power in Data Centers

As outlined in Cisco’s blog, “Co-Packaged Optics and an Open Ecosystem,” switch speeds have been doubling every two years. With each new generation of switches, networking is consuming a higher proportion of the data center power budget, as illustrated in the diagram below from the presentation “Co-packaged Optics in the Datacenter” by Rob Stone of Facebook.

This is a concern for data center operators for several reasons. As Philip T. Krein outlined in his paper “Data Center Challenges and Their Power Electronics”, power is a major challenge in today’s data centers, and anything that can be done to reduce the power consumption of the equipment in the data center is a benefit to the operator. Additionally, data center operators are paid for computing and storage, not moving data. Every watt spent on networking is a watt that can’t be used to generate revenue. Not to mention the impact on our Earth’s environment from the increased power consumption. Fortunately, CPO can help to address this challenge.

What are Co-Packaged Optics and How Do They Address the Power Challenge?

Our previous blog “Highly Integrated Silicon Photonics Light Engines in High-Speed Data Transport” shows the evolution of high-speed optical interfaces in the last 20 years. Pluggable optics has progressed from 1G to 100G with power per bit reduced drastically. As of today, 400G pluggable optics are being deployed in volume at mega-scale data centers and next-generation 800G pluggable optics is under development for 25.6T switches.

While pluggable optics solutions will be possible for 51.2T switches, we believe the industry needs to initiate a parallel development of CPO with the goal of first deployment in the 51.2T switch generation around 2024. CPO will complement pluggable optics in the quest of providing ever higher bandwidth while continuing to achieve lower power per bit.

With CPO, the optical interface in a networking switch system moves from pluggable modules at the front of the switch enclosure to optical modules that are assembled in the same package as the switch chip, as shown below.

Cisco’s blog explains the relationship between the power consumption of a communication link and the physical distance over which it must communicate. CPO takes advantage of this dynamic by moving the optical interface into the same package as the switch, thereby reducing the distance between the switch and the optics from inches to millimeters, thereby reducing the power of the switch-to-optics communication channel. While there are multiple alternatives for the die-to-die protocol between the switch and CPO, we believe that a power reduction of 30% or more is possible for a 51.2T switch.

Pluggable optical modules have been the mainstream implementation for optical connectivity over the last two decades, with an emphasis on the standardization of the form factors, electrical and optical interface specifications and interoperability between multiple vendors. A vast investment in technology has been made in the pluggable module ecosystem to accelerate at the integration of electronics and optics.

Starting at the 51.2T generation of switches pluggable modules will begin to coexist with CPO-based solutions. Over time, as the power and bandwidth challenges increase, data center operators will deploy an increasing proportion of their optical interfaces with CPO. The industry will leverage the readily available ecosystem and manufacturing capacity in place today for pluggable optical modules to support this transition.

The Need for an Open Ecosystem

The industry has a long history of standardization efforts such as the OIF, IEEE, and the MSAs, which have defined the standards for pluggable optical modules. These standardization efforts have resulted in products from a wide variety of suppliers that customers can be confident will work together, providing customers with choice, security of supply and shorter time to market.

As a precursor to a broader standards effort, today I am pleased to announce a partnership between Cisco and Inphi to cooperate on the definition of a CPO-based switch/optics solution to drive the industry forward and ensure interoperability between silicon and optical engines from different companies. This partnership will help our customers to enjoy a diverse and open ecosystem and interoperable best of breed technologies from a variety of suppliers.

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