The latest network buzz-phrase, "software-defined network" has been bandied about a great deal in techie circles lately. We asked Dan Pitt, executive director at the Open Networking Foundation in San Francisco, to explain to us what this new evolution in network technology is and where it might make sense for banks.

What is a software-defined network?

Software-defined networking is a disruptive technology that is making networks programmable by ordinary programmers using ordinary software running on ordinary operating systems in ordinary servers. With SDN, the introduction of new features becomes less manual, less prone to error and faster to implement. The OpenFlow standard - a communications protocol that allows the path of network packets through a network of switches to be determined by software running on multiple routers - provides the fundamental foundation for a software-defined network by giving a remote, logically centralized controller with a global view of the network and a consistent, system-wide programming interface the power to modify the behavior of network devices through a well-defined "forwarding instruction set." Instead of having each switch and router determine paths through the network independently based only on a destination address, the controller determines the optimal path for each flow based on a multitude of criteria determined by the network operator or user, and it conveys this information to the switches and routers using the OpenFlow protocol.

What can it do that a regular network can't do?

Software-defined networking and OpenFlow create the ability to program the network using ordinary software as rapidly and in as customized a fashion as you wish, meaning enterprises no longer have to rely on a vendor for updates. These new programmable networks enable new initiatives through flexibility, agility and virtualization, and the introduction of new features becomes less manual, less prone to error and faster to implement. Additionally, OpenFlow-based SDN lowers operating expenses and has fewer errors because of the reduction in manual configuration. It enables virtualization of the network and therefore the integration of the network with computing and storage so the entire IT operation can be governed more sleekly with a single suite of tools. This allows for better alignment of the network - and all of IT - to directly meet business objectives.

Can high performance be achieved in a software-defined network?

Using SDN, customers can determine and effect their own performance criteria of the network. Moreover, the independence of control and forwarding with SDN allows the technologies for each to develop independently and allows network operators to adopt new, high-performance technologies without requiring changes to the software and control investments they have already made. OpenFlow-based SDN fosters network virtualization and enables network operation to be governed by the user's requirements for security, policy, access control, load balancing, traffic engineering, and energy management as well as performance.

Can an existing network be made software-defined or is this only for new installations?

Yes it can, and we are seeing it coexist already. Numerous organizations introduce OpenFlow capability one device at a time into an existing network with convenient, logical separation of traffic and control. Ironically, OpenFlow-based SDN emerged from the Clean Slate Internet Design research program but does not require starting with a clean slate or with forklift upgrades.

What do Cisco, Juniper and the other traditional network providers think of this?

We cannot speak for any of our members. Cisco and Juniper are active member companies within the Foundation, and all members are seeing that their customers welcome open networking and network programmability, and are asking for standards-based approaches.




Your next network upgrade may include software-defined components.