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The Software-Defined Data Center and Software-Defined Networking: What Does It All Mean?

Software-Defined Networking (SDN) has become the center of heated discussions in the IT community, just like Big Data and The Cloud. This year, another term is being added to the list, the Software-Defined Data Center (SDD). As with any new trend or buzz word there is the question on whether these are valid, and if they will truly live up to their perceived potential.

This blog will help define these technologies, what stages they are in now and what segments of the IT department these technologies might help or hinder in the interim.

What is The Cloud?
While there’s not a lot of debate on what cloud technology is, starting with this term will help the discussion by introducing some key ideas.  While the canonical document comes from NIST, there is a much easier definition from Cloud Camp founder Dave Nielsen. In his view, cloud is OSSM (pronounced “awesome”):

  • On-demand: the server is already setup and ready to be deployed
  • Self-service: customer chooses what they want, when they want it
  • Scalable: customer can choose how much they want and ramp up if necessary
  • Measureable: there’s metering/reporting so you know you are getting what you pay for

The OSSM nature of cloud is driven by automation, controlled through orchestration. Customers use a cloud control panel portal, or an API, to monitor and configure their cloud instances at-will.

What is Software-Defined Networking?
SDN is a movement to apply automation and orchestration to networking equipment, in a manner similar to what cloud computing has done for virtual servers. The current common practice for configuring network devices requires a skilled engineer to configure each firewall, router, or switch separately when making a network change. In the words of Packet Pushers Podcast host Ethan Banks,

“To add a new VLAN and properly advertise it throughout the LAN/WAN, there are many steps required[…] I need to touch core switches, access switches, firewalls, and WAN routers[…] what should be a routine task is too darn complicated and mistake-prone.” (from the section titled “So, What Have We Got?”)

A single misconfiguration may lead to a cascade that takes down vital services – like GoDaddy on September 10, or Twitter in June. Therefore, it makes good sense to use orchestration to push configuration changes where they need to go, automating the process to reduce the amount of work and the number of errors.

As more companies are acquired and more companies start to use software-defined networking and OpenFlow, there is no doubt that this has huge potential. However, while centralized control of a network sounds good in theory, migration may require replacing a lot of hardware and the task of creating network-wide policies to emulate the current configuration would require a lot of effort.

What is the Software-Defined Data Center?
SDD combines techniques of cloud computing and SDN into a manageable scope. Datacenters are often the first places that new technology is deployed in production, such as SAN and lossless Ethernet, so adding enhanced orchestration is a natural fit to increase efficiency and reduce downtime. Virtualization architect Stuart Radnidge put forth an excellent vision of the power of SDD in his blog post “On the Software Defined Data Center.”

The essential idea of the software-defined data center is that specialized software will replace specialized hardware throughout the data center, reducing the tedious configuration work on a per-server and per-network-device basis. Derrick Harris of GigaOM describes the conversation he had in May with Steve Herrod, the CTO of VMware, about his vision and why this technology is important. At VMworld, the company came out with vCloudSuite 5.1, which really catapulted the phrase SDD onto the IT buzzword list.

SDD also has the potential to create virtualized converged overlays onto datacenter equipment, allowing servers to interoperate seamlessly with storage and networking.  Additionally, policy enforcement will allow logical separation of co-located equipment into separate virtual datacenters, reducing the concerns of multitenancy.

It will be interesting to see how these technologies evolve this year and into next. As acquisitions continue to be made and new products come out, each of these technologies will face challenges to live up to the hype.

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