Software Defined Network (SDN) Considerations for Commercial Network Service Providers

More than four years ago I wrote that carrier service providers must realize that they are in reality “application enablers” see (Going Horizontal on the Vertical) and that Service Providers needed to Virtualize the WAN.    These posts indicated two important areas that relevant to the discussion of Software Defined Networks (SDN) in the context of commercial services (A good summary of describing the SDN approach as compared to the prevalent distributed control model can be found at SDN A Backward Step Forward).

The two areas I described were that:

1. Network service providers have to provide an Application Programming Interface (API) for service requests and service status
2. Virtualization of the Core network enables customers to define what they want out of their network ensemble. 

It appears to me that the evolution of SDN technology needs to follow a similar path as virtual machine technologies.  That is the maturation of technology at the enterprise-level and then the transition to a commercial services provider’s infrastructure.  The first instantiation of virtual machine technology enabled the consolidation and increase in efficiency of an organization’s infrastructure.  The next steps were the development of multi-tenancy environments and transition into commercial “Cloud” services.

The successful public service provider SDN controller must be able to provide a user with the control needed by their application set, while at the same time enabling the service provider to optimize their network.  There are significant options about what the SDN concept means for a service provider and what it looks like to a customer:

1. Is the goal to provide “raw” virtualized standard router-type services? That is, does the customer select a router type and instantiate a set of virtual core routers to meet their requirements?
2. Is there a network equivalent of an x86_64 (i.e., Generic PC processor) virtual machine?  Do you provide a blank sheet and development environment for customers to create their own virtual network devices?
3. Is the goal to make it appear that the network is a single large “router” regardless of the number and physical locations of the actual network?  Wow, I get my own world-wide network that looks like a single router!  Can you also provide a “primary” and “backup” virtual router?
4. Do you provide a Plain Old IP VPN service for customers that just want the same-old-same-old basic service?
5. Do you provide multiple network personalities at the same time to a customer?  That is a network connection and control that enables both IP transport that appears as standard WAN VPN services (with traditional standard QoS – 99.9% packet delivery) as well as services that are more tailored data center operations such as moving Virtual Machines (with near Time Domain Multiplexed QoS – 100% packet delivery). 

As the “simplicity” increases from the customer perspective, the complexity for the service provider increases to manage the increasingly dynamic nature of the services offered and customer demands.

Finally, can we expect novel SDN-based capabilities to be provided by traditional network service providers, or do we need companies that “think outside the box” to move into this area?  If the introduction of large-scale Cloud services define the pattern, then companies like Google and Amazon may lead the network charge.