This article originally appeared in the January issue of INTERNET TELEPHONY magazine.

One of the most overlooked, yet also one of the most complex and critical, components to a successful cloud deployment is bridging the network between the on-premises data center resources with the off-premises cloud-based services. A network-level cloud interconnect tool is most often associated with a hybrid cloud, where application services are shared on- and off-premises, but these tools can also offer value for public and private clouds as well. At their core, cloud interconnection solutions are network tools: they connect two different data centers over the WAN. But with a few exceptions, we don’t see these tools getting mass attention when people talk about creating public, private, or hybrid clouds. Cloud interconnect tools can offer new and unique solutions for controlling and managing elastic resources, and they can also be strong differentiators for cloud providers as well.

Over the past year we’ve seen some rather larger movements in the cloud interconnect space despite not hearing much about this part of the cloud world. Most enterprise IT shops that approached cloud computing as an extension of their existing data center resources probably started looking at ways to connect cloud resources to their existing infrastructure from day one. In contrast, companies that were looking to completely off-load services to the cloud probably have only seen very basic cloud connection tools from their providers, such as simple IPsec or SSL VPN tunnels that allow the customers to securely transfer virtual machines and storage to the provider network. The whole connect your cloud market, much like other data center markets such application delivery or integrated storage, is one that you either know well or you don’t know at all, depending on your particular cloud needs and your maturity level for how you’re using the cloud.

There are more than a handful of true cloud interconnect solutions available – not counting the more basic transport-only solutions available from just about every cloud provider – but the two most well known technologies unsurprisingly come from the two big platform players: VMware and Citrix. That’s not to say that other advanced cloud interconnect tools don’t exist, but these two players seem to be getting the most attention with their branded solutions. The architectures of each option are completely different, but ultimately each delivers on the same overall promise of seamlessly connecting off-premises resources to on-premises data center management.

There’s no question that VMware’s vCloud Connector is the most well-known cloud interconnect solution, but it’s one of the most specific implementations available as well. vCloud Connector is explicitly tied to VMware products, linking multiple VMware cloud installations together through vSphere and vCloud Director so that they all appear as a single cloud instance. vCloud Connector is more of a lock-in solution as it requires other VMware’s virtual platform products. If you’ve already standardized on VMware then vCloud Connector is a logical choice for cloud interconnect, ease of management of off-premises resources, and for transparent migration for virtual machines; however, non-VMware shops will need to look elsewhere for a cloud interconnect solutions.

Cloud Bridge from Citrix isn’t as tied to the virtual platform like VMware’s vCloud Connector, but it’s also arguably the most convoluted of the big-name solutions. It’s a classic trade-off: You can do more with Cloud Bridge, but it takes more work and requires IT to make choices up front, such as deploying Cloud Bridge as a physical, virtual, or integrated solution. As of its release, Cloud Bridge is also limited to securing the connection to the cloud using IPsec, a very limiting networking option that may not be available from many external cloud providers. For bridging heterogeneous private clouds in different data centers, though, Cloud Bridge may be a good option for enterprises that have total and complete control over their own internal cloud environments and prefer flexibility over turnkey.

Although it is technically possible to achieve a hybrid computing model or to build an architecture that supports cloud bursting without using a cloud interconnection tool, much of the benefits from elastic computing are lost when the elasticity can’t span on- and off-premises resources. The importance of linking an external cloud platform to the internal data center fabric can’t be overstated. Technologies that bridge the external cloud environment with the internal data center will become a requirement in short order, and in a few years we’ll be looking back wondering how we ever lived with, and trusted, our apps in an unmanaged cloud. Regardless of the pros and cons of each, or the reasons for choosing one over the other, it’s important that IT start integrating and using one of these technologies today so that future cloud growth can be build around a connected network.

Alan Murphy is technical marketing manager of management and virtualization solutions with F5 Networks (News - Alert) (www.f5.com).