SDN may not be a fit for everyone, but it's definitely going to play a big role in the networks of the future.
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While there are a few minor issues around process and SDN maturity, these are quickly being sorted out since there is so much potential for efficiency gains.
What's a hybrid network?
Your next network will be a hybrid. Physical hardware isn't going anywhere in the near term, but the odds of encountering SDN technologies in production in the next three years are very high. The rollout of virtualization concepts to both the network control and data planes is a dramatic shift, but they also align well with virtualization concepts already in use.
If you run a network, chances are you support multiple vendors in the infrastructure. For every network maintenance or upgrade, you can end up with downtime, rollbacks and general "unhappiness" -- whether you are a service provider supporting enterprise customers or a medium-sized enterprise with a distributed workforce across multiple data centers.
SDN acknowledges the reality of networks today; administrators are dealing with multiple vendors and technologies with multiple layers. With the "new reality" of dynamic virtual workloads and networks that shuttle traffic between data centers, something has to change.
Ten years ago, cloud talk resulted in combining components of the data center, such as networking, computing and storage. As anyone who has built these solutions can attest, the networking component relied on a combination of hardware and software, along with expertise and nerves of steel for configuration.
SDN aims to update that in a big way, but not without problems. The issue is that there are different visions of SDN, since network evokes different concepts. The focus of SDN is on combining concepts of virtualization to the network stack. In theory, this approach should simplify network architectures and permit dynamic workloads to behave consistently across hypervisors, data centers, and the like. Vendors use different approaches; some use software plug-ins with existing technologies, some use proprietary hardware, but all promise to ease the pain of network provisioning.
How does SDN work?
There are two functional areas at the core of SDN: the control plane and the data plane. The control plane is the control layer on top of the network elements of hardware and software running downstream (similar to how a hypervisor interacts with the server environment under its control, while still working alongside a centralized management layer). The data plane is everything else -- what we would imagine as the tangle of network wires and cross-connects. It catalogs and assigns relevant metadata so that the control layer can manage the architecture and configuration elements without getting in the way. Of course, since these control elements can now see the entire picture of the network and the typical configuration risks are mitigated, new opportunities for efficiency open up.
While the concepts and use cases for SDN look very promising for a service provider or an enterprise, network configuration continues to be a hassle for administrators.
SDN is still maturing. Since networks and backbones are mission critical in any business, adoption is going to take time. But in the same way that mission-critical applications were eventually virtualized on servers, data centers will see new and exciting opportunities in SDN.
One of the significant upsides of SDN is the drive to application programming interface (API). Hardware and software vendors that have relied on secure shell and command line interfaces (CLIs), and/or bolt-on APIs, are now putting significant effort into conventional Web service APIs. With a surge of attention, the integration of SDN technologies is easier, and also provides a reasonable upgrade path. OpenFlow is a key technology that is helping to unify SDN technology around functionality versus vendor agendas.
Another trend is service providers driving some SDN technologies with their enterprise customers. Whether it is with the API or a manifestation of the software-defined data center, expect to see service providers use SDN downstream to further differentiate themselves. As enterprises look to selectively move workloads around, service providers have a great opportunity to keep the process simple and to leverage various virtualization platforms.
How to manage SDN in your environment
One of the misconceptions about the phrase network provisioning is that infrastructure is included. If you are still using spreadsheets and CLIs to manage your IP addresses and DNS zones, then SDN implementation will be more complex. Having automation or APIs in place prior to SDN ensures that even a pilot can be met with success and show value across the complete resource provisioning process.
Given SDN's roots in virtualization, it would make sense to look at doing a test deployment in that arena first to see how it might have a broader fit in your organization.
SDN is not a replacement for sound business processes. Identify the issues that you would like to address with regards to network management and establish how this relates to your virtualization strategy. This will help align your technical options with your implementation goals. There is still no "magic button" to configure the information, but this gets you pretty close, with little preparation.
Understand how your current automation platforms (network, hypervisor, configuration) are going to work together with SDN. Some platforms have more robust APIs than others, which will impact development and integration requirements. If you have holes in your provisioning process, SDN will make them more obvious.
Pete Sclafani is chief information officer with 6connect, a provider of network automation services. Contact him at firstname.lastname@example.org.