Last week, after VMware introduced businesses to the idea of an automated cloud service portal called vCloud Integration Manager (vCIM) that could give private cloud consumers a way to become public cloud providers, the question was: How many small-to-medium enterprises would jump on board? Interrupting the answer to that question today is AT&T - arguably still one of the world's largest public corporations - which has itself become a vCloud customer in a retooling of its Synaptic cloud services to include VPN access.

It's a move that could not only help AT&T gain parity, or something approaching it, compared to cloud giant Amazon, but could also help even the stakes between VMware and Citrix in the one field where the latter's Xen has a market share advantage: the private cloud.

The story of AT&T's cloud rollout begins in 2006, with the acquisition of what was then considered a "business management service" called USi. That company had been working on cloud infrastructure initiatives.

In August 2008, AT&T began rolling out the first cloud services based on those initiatives, under the Synaptic banner. At the time, the company claimed Synaptic would effectively invent the genre of cloud computing. When asked to differentiate Synaptic from other cloud services offered by Amazon and others, the company told my reporter at the time that, unlike its competition, AT&T would be offering hosting and storage on an unprecedented kind of "pay-as-you-go" model, something like an on-demand cable TV program.

What became painfully obvious was that a golden opportunity circa 2006 had become an also-ran play when extended into 2008. The following year, Amazon introduced its first VPN service, which when you look at it from a wider-angle lens was actually its portal into a hybrid cloud. Not really a VPN by the original definition, but perhaps a "virtual VPN," its premise was to enable customers to determine how much compute and storage resources should reside on-premise, and how much may be extended into the public cloud, and vary that ratio as necessary.

This morning, AT&T announced what it's calling a "VPN-based cloud," which actually refers to the remote access portal enabled through the integration of VMware's vCloud. It is vCloud which will open a path for existing VMware vSphere customers to migrate their resources quantitatively into AT&T's space without having to re-design their data centers.

In this diagram provided last week by VMware of vCloud Integration Manager, the top row contains components that may now be provided by AT&T, among others.

During an interview last week, VMware Senior Director for Cloud Services Matthew Lodge described how customers who already utilize vCloud Director for managing private cloud infrastructures (released in 2010) would be able to provision cloud-based services offered by a vCloud-participating data center, bringing their compute, storage, and network power into their service pools. Today's announcement effectively puts AT&T Synaptic in that category. The hope is that this enables an homogenous platform between the public and private clouds that can effectively be managed through a single portal.

We asked Lodge last week whether vCIM would be capable of effectively aggregating service pools from multiple vCloud participants. Such a feature might give AT&T's new service at least a toehold into hybrid environments where other providers already have a head start. Lodge responded no, not with this current version, though such functionality is being considered for a future release.

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