SDN Introduces Choice To The Data Center

Three buzzwords commonly heard today in the world of data centers are scalability, flexibility and choice. Corporations seek solutions that allow them to expand their network easily and inexpensively, while maintaining the option to choose their equipment without being wedded to their previous or future vendors.

Traditionally, data center networks have comprised a large number of switches and routers that direct traffic based on the limited view of each device. The hardware was coupled with software to manage traffic flows within the small patch of connectivity that was in the purview of those specific devices.

Network limitations

This model for networking, while effective to the extent that it improved upon even more antiquated methods of passing data, cannot meet the flexibility required to deliver today's massive amounts of data. Moreover, when the hardware and software are coupled, the network becomes expensive to maintain, expensive to scale, and lacks the capability for users to innovate and administrators to tune applications.

Perhaps most troubling, such solutions are traditionally vendor-specific, locking companies into consuming not only the vendor's hardware, but also the vendor's predetermined configuration and routing protocol, its tools and training, and its feature roadmap. In many cases, a significant portion of these features might be intended for other markets and would normally not be used; but with vendor lock-in, customers must align to vendor plans.

This leaves corporations with gaping areas in need of improvement, most pressingly in their desire to properly leverage data and their need to optimize their data center to handle compute, storage and networking needs.

Leveraging SDN

To address these issues, companies are turning to software-defined networking (SDN). SDN services, typically controlled and monitored from centrally located sources, take a global view of the entire network. With SDN, traffic flow is managed with software applications, which are significantly more dynamic and allow optimization and tuning not available in locally managed switches and routers.

Scalability is easily achieved in SDN, since the software scales to as many switches or routers as there are in the network. Adding hardware simply creates new pathways for the software to manage, monitor, and use to create the most efficient traffic flow.

With a central SDN solution, the network routing can be customized more easily as well, shaping it to the specific interests and needs of that data center. Whether a company is seeking high-performance computing, Web 2.0 or cloud provisioning from its data center, SDN enables a tailored network experience that will increase speed and flexibility, thereby encouraging innovation.

SDN can be adapted to any equipment type, such that it is vendor-neutral. As long as there are common SDN interfaces to the devices in the network, it does not matter to your applications who provided the hardware or which operating system is being used. By using algorithms to create a solution, SDN relies on OpenFlow, Puppet, and other protocols to remain agile and flexible, as well as cost-efficient.

Filling the SDN "hole"

One of the "holes" in SDN is the ability to guarantee service delivery. While SDN tools can detect congestion, and in some cases can reduce congestion, they cannot prevent data loss. SDN applications can only report on data loss after it has happened. To address this, the network must be reliable and non-blocking, regardless of its management interfaces (SDN or other). Only networks that are comprised of non-blocking switches and routers are able to leverage all the SDN benefits.

These switches are usually designed around a main switching IC and inherit its features and limitations. Therefore, the switching IC in use should meet the full network line rate and should not unnecessarily store data in its internal buffers. If the switching IC fails to do so, it will create congestion and packet loss, which the SDN applications cannot resolve.

Opportunities with Open Ethernet

SDN is actually part of the Open Ethernet architecture, which separates hardware and software functions, establishing a common software interface between the two parts and enabling companies to select a hardware vendor separately from the software vendor. Open Ethernet enables greater flexibility and choice by providing the tools to alter the software that runs on the hardware, not simply the ability to control it remotely.

This separation of the software from the hardware enables a greater level of flexibility, providing the means to optimize the hardware for a specific deployment. Community-based collaboration, such as the Open Network Install environment (ONIE) and Switch Abstraction Interface (SAI), both driven in the Open Compute Project (OCP), are targeting the easy replacement of the switch and router OS while in-service and upon a change in the data center.

Open Ethernet (and SDN) restores control of the network to the data center owner, enabling the company to scale its network based on its own considerations, rather than based on existing vendor solutions. It provides more flexibility in configuring network traffic flow, better monitoring and smoother removal of inefficiencies and bottlenecks, and a more cost-effective answer for today's data centers than traditional networking solutions.