Growth of cloud-based services shows no real signs of slowing down. This adoption rate is propelling providers of cloud services to construct new data center capacity, work to make data centers they already have run more efficiently and improve how they network their data centers internally.
In early adoption phases of cloud, there have been two dominant uses of data center interconnection (DCI). First is for connecting enterprise data centers to service providers’ data centers for hybrid and public cloud computing services. The second use has been to connect providers’ ecosystem partner data centers to SPs’ data centers to mash up applications and federate cloud services.
As usage has grown, though, a new set of DCI requirements has emerged. These involve connecting providers’ own data centers at very high capacities. Two scenarios dominate this trend. The first is in metro or nearby data center connections, and the second is in hyper-scale data centers deployed at great distances from other sites and running at remarkable scale.
In the first use case operators will run out of power or space in existing sites and need to create additional capacity nearby. This can be in a metro area footprint or in an extended campus. DCI is critical in these deployments because many cloud applications work in a highly distributed model. They often need access to resources in neighboring data centers many times over before responding to a single user’s request. Thus, interconnections need to be simple and fast.
In the second deployment scenario, hyper-scale operators such as Google, Facebook and Microsoft search for remote locations where land and power are less expensive and build some of the world’s largest data centers there to run their services. Server counts in these sites range from 200,000 to 500,000 or more. The need for integration with systems in the providers’ other data centers is strong in mega-site deployments as well. This leads to extremely large capacities of DCI bandwidth being deployed both locally in clustered DC locations as well as over long haul transport for sites that are a half a continent or more away.
DCI capacities required in the intra-provider configurations range from 10s of tb/s in medium-to-large scale sites to several hundred tb/s in the largest mega-center locations. Because of the ongoing growth in the use of providers’ services, the unique needs of these DCI deployments have led to the emergence of a new type of high-capacity DCI solution.
Five requirements define the new breed:
- Efficient and flexible scaling to 100s of tb/s of transport
- Compact, rackable form factors
- Low power consumption
- Simple operation
- Programmability for integration with service automation
Underpinnings of these requirements
A dominant aspect of cloud data centers is use of infrastructure such as servers and storage systems that are modest in unit size but able to be pooled in wide ranges of capacity to serve the needs of application or service. This leads to a bias for systems installable in compact, rackable form factors that are easy to install and expand, often leveraging auto-configuration for integration into infrastructures at very large scale.
Form factor compactness demands low power consumption. If an individual server consumes, say, 150 watts in ongoing use, a rack of 40 such servers might consume 6 kilowatts, sustained. A data center with 100,000 such servers might consume 15 megawatts (approximately estimated). It’s easy to understand why cloud providers focus on wringing every possible watt out of solutions they deploy. DCI platforms designed in a more server-like package (versus a telco office orientation) are likely to consume less power, perhaps drawing a third less power per rack than alternatives. Across 10 racks’ worth of devices, if 150-200 kilowatts of power can be saved, a solution is heading in the right direction.
A final objective that fits with the ability to pool resources goal is to support open, programmable software for DCI capacity to be dynamically provisioned according to application needs. A variety of approaches can be taken to achieve this, including plug-ins for service control software rapidly evolving for use in cloud and virtual networking infrastructures as well as API toolkits to let large cloud providers integrate with their own service management platforms. In the end, programmability to support adaptation to providers’ goals for resiliency, path allocation, and application-driven solutions are the key requirements.
This new breed of DCI solution will complement other transport solutions that implement shared network transport of various types in metro and long haul configurations. The two styles will be used by providers for different types of connections. Both will be used to support higher level service requirements for customer, partner, and internal operator data center connections.
The Cloud Xpress family introduced by Infinera is an innovative example of the kind of high capacity, small form factor, programmable DCI platform cloud operators are leaning toward for their internal DCI deployments. Cloud Xpress is initially targeted for metro deployments. Leveraging optical innovations Infinera has previously introduced and engineering them into a platform capable of 20+ tb/s in a single rack, Cloud Xpress is an impressive contribution to the state of the DCI art. If trials prove out successfully, Cloud Xpress has every prospect of helping cloud operators scale out their data center deployments and interconnect them with the capacity and elasticity they desire.
For more information refer to “Rise of High-Capacity Data Center Interconnect in Hyper-Scale Service Provider Systems.”
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