Software defined networking FAQs: Gartner

Software defined networking (SDN) is creating a lot of excitement in data centREs, but current technology is still relatively immature. In the new research note "Ending The Confusion Around Software Defined Networking (SDN): A Taxonomy", Joe Skorupa, vice president and distinguished analyst at Gartner, explains that SDN is not only limited to data center and service provider networks.

Skorupa answered some questions around the current state of SDN and how it will evolve:

Q - What is Software Defined Networking?

A - (SDN is a new approach to designing, building and operating networks that supports business agility. SDN brings a similar degree of agility to networks that abstraction, virtualization and orchestration have brought to server infrastructure.

In the SDN architecture, the control and data planes are decoupled, network intelligence and state are logically centralized, and the underlying network infrastructure is abstracted from network applications and features. In addition, programmability enables external control and automation that allow for highly scalable, flexible networks that readily adapt to changing business needs.

While a great deal of attention has been directed toward SDN in data center networks and service provider networks, it can also be applied to campus networks and, enterprise WANs. The applicability and benefits will vary by use case.

Q - What Models Exist for SDN Deployment?

A - Three deployment approaches are possible - switched-based, overlay and hybrid. For greenfield deployments, particularly when the cost of physical infrastructure and multi-vendor options are important, a switch-based model will be common. The biggest limitation to this approach is that is currently does not leverage existing L2/3 network equipment.

When rapid deployment over an existing IP network, or when responsibility for the SDN environment is assigned to the server virtualization team, a tunnel-based overlay approach may be appropriate. With this approach the SDN endpoints are virtual devices that are part of the hypervisor environment. The greatest limitations of this approach are that it does not address the overhead of managing the underlying infrastructure, de-bugging problems in an overlay can be complex and it does not support bare metal hosts.

The third approach combines the first two into a hybrid deployment. This allows a non-disruptive migration with a path toward an eventual switch-based design. Gateways link devices that do not natively support overlay tunnels, such as bare metal servers.

Q - Where might SDN be Leveraged?

A - In a data center context, SDN is a component of the Policy Driven Data Center. It provides the programmable connectivity required to link the network to other components within the data center delivering a more integrated, functional system. For example, a provisioning application could specify that an instance of the CRM application must have certain services delivered in a specific sequence and would ensure that the traffic flows through the appropriate devices in the correct sequence.

In a service provider context SDN might be leveraged to provide a common control plane across multiple vendors equipment including SGSN/GGSN, PE router, session border controller, core router, optical transport/WDM nodes to build an agile, multi-tenant network that is a platform for value added services. Possible service offering could include flexible bandwidth on demand, patch protection/restoration and multi-casting. SDN promises easier integration with OSS/BSS to increase service agility while reducing CapEx and OpEx.

Q: How Can I Decide if SDN is Right for My Organization?

A: Begin to explore the potential benefits and risks that SDN will bring to your organization, but beware of SDN-washing which simply re-labels legacy approaches with the latest buzzwords.

Be aware that SDN has significant potential impacts on security. Your security strategy must evolve with the SDN strategy to incorporate new needs and opportunities brought on by SDN.

If you focus on the data center network first, be sure to involve server, virtualization, security and storage teams in the discussion to ensure a single approach is adopted.

The adoption of SDN requires a new way of thinking that may threaten existing network engineers. Identify members of your team with the skills and vision to lead the evaluation process.