Software defined networking is generating lots of buzz these days as the next step in virtualization. Essentially, it’s a way to “virtualize” network infrastructure, in much the same way that most companies have already virtualized servers and perhaps storage and desktops. 
To get a handle on what SDNs are all about and the role they can play, we talked with Sameer Mohile, a senior product manager with Extreme Networks. Extreme is a network infrastructure vendor (and Carousel Industries partner) that in July announced some new initiatives relative to its own SDN strategy.
Explaining Software Defined Networking
SDNs bring to network infrastructure the kind of programmability that is common with software. Traditionally, every switch and router in a network has its own control and data plane, which means all routing decisions are made on the switch itself.
The idea behind SDNs is to abstract that control plane from the switches and routers and run it on a central controller. That leaves the switches with just the data plane that actually ships packets in and out; the decisions on where the packets will go is based on instructions coming from that central controller, Mohile says.
That setup gives you more control over data flows as well as multi-vendor support. Any switch that supports the OpenFlow protocol that is used to create SDNs will be able to work with an OpenFlow-compatible controller. “You can have a true multi-vendor deployment and interoperability,” he says.
The Role of SDNs in a Virtualized Environment
SDNs also play a key role in a highly virtualized environment, where it’s common for virtual machines to be added and moved regularly. Such an environment can be difficult to support with traditional network infrastructure, which relies on fairly static connections between switches and servers.
With SDNs, however, those connections can be made more dynamically, and with the proper level of security. It’s similar to the multi-tenant concept of server virtualization, where a single server can support multiple virtual machines, Mohile says. SDNs enable a single switch to have separate data planes, each with its own service level that is appropriate for each data flow. “You are giving resources to different tenants at different times,” he says. “Every tenant doesn’t get the same resources each time.”
SDNs Are All About the Applications
For its own SDN initiative, Extreme decided to focus on four areas, he said. First, it opted to support the OpenFlow protocol and associated APIs, as the company deemed it the most open, fully baked protocol for SDNs. Secondly, Extreme supports OpenStack, which is a set of services that essentially provides the orchestration on top of a controller that enables the controller to interact with various switches.
Extreme also decided to strictly follow the OpenFlow 1.0 specification. “We don’t want to restrict customers to using just one or two vendors, so we have to strictly follow the 1.0 spec,” Mohile says. That means Extreme won’t be adding any “special sauces” on top that might disrupt interoperability. “Any controller that’s compliant with the OpenFlow 1.0 spec will work with our switches.” Initially, Extreme has marketing relationships for controllers from NEC and Big Switch Networks.
But the real value-add with SDNs, he says, is the applications that run in the environment. It’s similar to the smartphone environment. While the phones themselves are nice, it’s the applications that run on them that make the phones truly useful. Just like Apple and Google, Extreme is taking an open approach to application development by launching xKIT, a new application and knowledge base portal for sharing applications. “Anyone can contribute applications and work with our infrastructure,” Mohile says.
A security application, for example, could help companies address the bring your own device trend. An OpenFlow application could identify a device when it connects to the network and immediately apply the appropriate security policy, and ensure the policy remains in place as the user moves about the network. “The central controller knows the device has moved and applies security policies on the fly,” he says.
Extreme will support OpenFlow and OpenStack across its entire line of switches, and Carousel will be on hand to help customers make the most of this exciting technology. To learn more, contact Carousel.
