Like other software defined initiatives, software defined networking (SDN) abstracts the networking operating environment from the hardware switches and controller. The SDN promise is to reduce costs and improve operational efficiency by managing a set of physical top of rack switches and higher density spine switches with a single controller, treating the entire network as one logical switch. It advances network operations from a proprietary and command line driven environment that network administrators have to manage on a per switch, CLI based approach, to a nimble, agile network that is open and can evolve at the pace of the modern data center.
Comparing SDS and Virtualization
For IT professionals that are unfamiliar with SDN, it is best to compare it to software-defined storage (SDS) and/or hyper-converged infrastructure (HCI). SDS abstracts the storage software from the physical storage hardware so that the same storage operating environment can work across multiple vendor’s storage systems or can cluster dissimilar commodity storage servers into a single cluster. SDS promises the freedom to select hardware from whichever vendor the data center prefers, with dramatically simplified management of the storage infrastructure.
SDS also simplifies operations. Storage administrators can now use the same commands to mount storage volumes, assign those volumes and take snapshots of them, all from a single interface.
In the same way, HCI abstracts the operating system software as well as storage software from physical hardware. Once virtualized, servers and storage software can now run on almost any hardware platform and even move between servers within the cluster without change. Instead of administrators having to learn specific management solutions from the various server vendors, they can manage servers and provision compute and storage resources on a per VM basis from a single console.
In both cases, the eventual outcome is the use of highly commoditized, often referred to as white box, server hardware, which drives down the acquisition costs of both servers and storage, significantly. The result is that software defined servers and storage provide an ROI in multiple ways, better utilization of the hardware, improved operational efficiency and specific hard cost reductions.
SDN creates a very similar scenario for the network. SDN enables the organization to use white box network switches (or branded white box switches from Dell EMC or HPE), which are essentially switches without any networking software based on industry standard hardware specifications. The SDN solution then controls these various switches creating a scale-out architecture in which it manages many small switches as one logical switch. The result is dramatically simplified network operations, automation and reduced costs.
What is a White Box Switch?
A key aspect of SDN is its ability to leverage white box (industry-standard) switches. When most IT professionals think of network switches, one or two of the tier one vendors come to mind. The hardware from these vendors includes custom hardware and ASICs, which those vendors claim gives them a unique value in the market. It also enables them to charge a premium for their hardware. White box switches are at the opposite end of the spectrum. They are inexpensive switches with very basic networking features built in and are an ideal candidate for SDN software. Hyperscale players like Facebook, Google, Amazon and others have proven that white box based networks can scale, as long as intelligent control software is deployed on each switch. Adding SDN software to white box switches gives all of the capabilities of their name brand competitors, often at half the cost. Established system vendors including Dell EMC and HPE now offer disaggregated switching solutions – industry standard switch hardware, with a choice of SDN software solutions that meet different customer environments / needs.
How Does SDN Reduce Hard Costs?
The ability to leverage white box switches is a big reason that SDN becomes a less expensive alternative to name brand switches. The combination of the SDN software and the white box switch hardware is considerably less expensive than the turnkey name brand solutions.
A potential concern that may be brought up is that the organization may have to deal with two support organizations, one for the switch hardware and one for the SDN software. The reality is that Dell EMC and HPE offer first line of support for the joint SDN / industry standard solutions. Even turnkey, proprietary networking vendors will admit that the large majority of their support questions are related to software.
SDN is also less expensive to upgrade. First, the next switch can come from any white box switch vendor; the customer is not locked into the first switch they bought from vendor X. That means that pricing remains competitive throughout the upgrade process. Second, upgrades are really just expansions to the original design. Network administrators just add one more switch that is added to the logical management pod automatically. It becomes part of the switch cluster all managed by the SDN Software.
How Does SDN Reduce Operational Costs?
Eliminating the upgrade process is one way that SDN reduces operation costs in addition to hardware costs. SDN also makes the process of provisioning that new switch much easier, as it has every switch under its control. Some SDN solutions can also provide workflow automation so the newly provisioned virtual machines and applications can automatically and programmatically get their port assignments and port configurations. Lastly, since SDN is controlling the switch fabric it has deep insight into what is going on in the network. An SDN can provide detailed telemetry on network events so that IT can fine tune to make sure it eliminates problems before they cause work stoppages.
Every data center should, at a minimum, be exploring SDN. It has a role to play in almost every virtualized and hyper-converged environment. It can drive down the cost of network infrastructure, integrates into leading HCI solutions like Nutanix, Scale IO and VMware VSAN to automate and simplify network provisioning, which enables faster adoption of next generation networking technology while at the same time increase IT efficiency.