Opinion: Optical DCI & the Future of Data Centers

The NGON Series team is working with some of the most renowned companies, solution providers and professionals in the next generation and data center industries on a few topics and trends shaping the optical networking industry, and which will also be further discussed at NGON and Optical DCI 2017 in Nice.

Our first opinion piece, with insights from ADVA, Source Photonics and ZTE, unfolds optical DCI and the future of data centers.

What is the future of data centers?

ADVA Optical Networking
The data center deployment model is changing. In addition to large, hyper-scale data centers and central content delivery instances in each geographic region, multiple edge or on-ramp data centers are being deployed as we speak. Starting in the U.S., this trend is now also observed in Europe and Asia. Extending the Internet at the edge by moving data centers closer to the consumer and enterprises reduces latencies, increases application responsiveness, improves security and helps lowering transport cost by keeping most of the traffic in the metro.

Source Photonics
Data centers have seen a transition phase in the past few years as cloud scale data centers have entered the market. The cloud scale data centers have started to migrate to 100G optics in 2016 and it is anticipated that this will continue for the years to come. Enterprise DCs are currently still using 1G and 10G optics and are a few years behind the cloud scale datacentres with regard to mgration to higher data rates.

The demand for higher datarates in cloud scale data centers will see early adoption of 400G optics for switch interconnects in 2018 and the volume ramp for these optics will start in the 2019/2020 timeframe. Cloud scale data centers will surpass the enterprise market in optical spend by 2018/2018. A general trend has also been the migration from multi mode fiber optics to single mode fiber optics for cloud scale data centers.

ZTE
With the rapid growth of emerging industries like big data, cloud computing and smart terminal, the global data center industry is expanding significantly, and the ecosystem is getting more intelligent and healthy. Meanwhile, the data center industry is taking on new characteristics with the upgrade of requirements and technologies.

ZTE believes that the future data center has the following features from a technological perspective:

1. Virtualized resources: flexible and on-demand
New concepts are introduced, like on-demand data center, service-based resource scheduling, and elastic module. With the development and application of cloud computing, separation of hardware and software is implemented for computing, storage and network; resources, including computing and storage, are virtualized and shared in a resource pool; software-defined data centers support flexible scheduling of resources.

2. Modular infrastructure: Building a data center is like building blocks
This modular design maximizes the use of infrastructure and saves on the customer's investment. On-demand expansion makes a data center more efficient in energy.

3. Higher energy efficiency: Power usage effectiveness (PUE) is lower than 1.2. Power density increases from 3–8 KW to 10 KW and even 20 KW
High-density data centers can process more data requirements in a more efficient manner. Higher energy efficiency reduces the energy use of data centers and consequently the customer's Opex.

4. Intelligent operation and maintenance: unattended, guarantees the reliability and performance of services, and improves quality and efficiency
With the generation of massive connection, the number of data center will increase in large-scale. ZTE is committed to the research and development of cloud-computing. Being one of the pioneers in the development of cloud-computing, ZTE has built an architecture that consists of one data centre, two platforms (cloud platform and Big Data platform) and multiple cloud applications. Based on this the company will cooperate with its global partners in the field of data center in the M-ICT era.

What are the next optical innovations within the data center?

ADVA Optical Networking
Within the data center, 100G connectivity is becoming state of the art. We see this already in some of the hyper-scale data centers and first signs of this trend for smaller facilities as well. Additionally, virtualization across data centers has become an important function to increase efficiencies and utilization of resources. This requires ultra-high speed connectivity at minimum latency to move virtual machines and other tasks in real time.

On the architectural side, open line systems directly interconnected to colored interfaces situated in spine switches. This disaggregated solution approach receives significant interest and is about to be deployed by some of the major internet content providers.

Source Photonics
The traditional model of OEMs providing optics is replaced by a model of cloud scale data center operators buying the optics directly from optical module manufacturers. This opens the market for proprietary solutions that fit exactly the needs of the customers. However, standardized solutions tend to offer a better cost structure due to the larger volume they command. In the next few years the cloud scale DC sill be dominated by 100G CWDM4 and PSM4 PMDs.

LR4 type PMDs will be widely used on the edge of the DC as well as in applications that require a high loss budget. First Silicon Photonics based devices started to ship into the DC in 2016, but their application space is limited and discrete technology still dominates the market. At the end of 2017, iC companies start to sample switching silicon that offers higher order modulation such as PAM4 instead of NRZ.

The past has shown that the lowest cost modules have the same electrical and optical data rate, so 2018 will see the first modules that support higher order modulation like PAM4 inside the DC for 100G, 400G and possibly 200G applications.

ZTE
In the next three to five years, the market trends for optical DCI are as follows:

1.At present, telecom operators and Internet Service Providers (ISPs) are competing to build cloud data centers. According to the consultancies, the data center business will grow threefold from 2013 to 2018, with the Internet Content Providers (ICPs) boasting the fastest growth. It is estimated that in the next three to five years, the data center service bandwidth will still maintain an annual growth rate of 20 to 30 percent. Data Center Interconnection (DCI) involves long-distance backbone DCI networks and Metro DCI networks, with the latter growing faster.

2.According to the evolution of output interfaces on high-speed routers in large IDC centers, currently the 400 Gbps rate can hardly be exceeded. Commercial demands for high-speed 400 Gbps routers are expected to emerge around 2018.

3.High bandwidth, long distance, short delay, and high reliability are the core needs of DCI. Large data centers use intra-city backup and remote disaster recovery for higher reliability of the entire network and business services, posing extremely high requirements for the reliability measures on the underlying bearer network, such as protection, and recovery. In addition, inter-IDC services need real-time or regular backup, requiring as short of a delay as possible for inter-IDC 10 GE and 100 GE service transmission. High-capacity OTN technologies can fully meet the core needs of DCI, and will remain to be the inevitable choice of DCI in the future.

4.In the telecom operator market, Central Office (CO) reconstruction facilitates the construction of edge DCs, and vDCs will be established between edge DCs and between edge and regional DCs through DCI. Therefore, cloud-based deployment is the future trend for data centers.

5.In the Internet service provider market involving Facebook, Google, Tencent, and Baidu, Internet companies are under great pressure of competition, and are in urgent need of rapid deployment and commissioning of the DCI service. However, common data center cabinets are designed with front air intake and rear air outtake, while traditional large-capacity OTN cross-equipment generally use vertical air ducts, with high power consumption on each device. In addition, the Internet CO reconstruction before equipment deployment is time-consuming, resulting in failure in fast deployment and service commissioning. In this context, ZTE develops a compact ultra-100G OTN device. The ZXONE 7000, a compact ultra-100G OTN device for the DCI of ISPs, will be released in the near future.

6.In the future, the unified scheduling of SDN controllers allows the compact ultra-100G OTN device, the OA, and the OMD and ODU in one network, implementing inter-DC SDN service scheduling and fault recovery.

Metro DCI - is DCI going to help the Metro network?

ADVA Optical Networking
Depends on what you mean by helping the metro network. The rise of edge and on-ramp data centers will clearly reduce traffic in the metro core. And this is essential to support increasingly time-sensitive applications and support the foreseen growth of cloud services in an economic way.

On the other hand, metro connectivity between data centers becomes key to assure peering flexibility with all major cloud providers. Operating a data center is no more providing space and power only. Hosting applications and enabling effective peering with as many cloud service providers as possible has become a key differentiator. The metro optical network – and also some long distance connectivity to major hosting hubs – has become a key differentiating element for data center operators.

Source Photonics
Cloud scale data centers have started to develop their own optics to meet their cost and performance objectives for their data center interconnect requirements. It is anticipated that this will migrate into the metro market but one has to take into account the differences in network topology between the China and US metro market as standardised solutions are preferred in the metro market if one does not own both ends of the link.

ZTE
DCI is mainly used for interconnection between 10 GE and 100 GE services, and 100 GE services account for an increasingly large proportion. This promotes the evolution of the Metro OTNs from the nx100G system to the nx200G and nx400G systems, facilitating the sophistication of the entire ultra-100G industry chain and reducing network construction cost.

In the operator's market, CO reconstruction brings about vDC deployment. In addition, with a flexible deployment of the cloud-based CU function in the future 5G networks, services can be dynamically changed according to user needs or network faults. This accelerates the SDN industrialisation of DCI OTNs, and the future Metro OTNs will be more elastic, intelligent, and efficient.