Vice President of Solutions and Outbound Marketing
SDN is garnering a lot of media attention of late, but there are still many unknowns regarding how radical a change it will bring to existing network architectures. The very notion of separating the control and data planes opens up the possibility of highly dynamic network environments that can be instantly optimized for individual application and user requirements. But with much of the technology still on the drawing board, it can be difficult to separate fact from fiction. In a conversation with IT Business Edge’s Arthur Cole, Solarflare’s vice president of solutions and outbound marketing, Bruce Tolley, offers insight into what is real, and what is merely possible.
Cole: Software-defined networking is on a roll these days, but it has barely made an impact on production environments. What are the main challenges in bringing SDN to the mainstream?
Tolley: Software-defined networking (SDN) is an approach to building computer networks that separates and abstracts elements of the network systems into the control plane and the data plane. The control plane manages switch and routing tables while the forwarding plane performs the Layer 2 and 3 filtering, forwarding and routing. SDN decouples the system that makes decisions about where traffic is sent, the control plane, from the underlying system that forwards traffic to the selected destination, the data plane.
SDN promises to simplify networking and enable new applications, such as network virtualization, in which the control plane is separated from the data plane and implemented in a software application. While mainly driven by the data center architects at the big Web 2.0 companies, this architecture allows enterprise IT managers to have programmable central control of network traffic without requiring physical access to the network's hardware devices. Many SDN advocates look to the example of the Linux community and the open source movement as an example of how users and customers can drive software innovation on top of an ecosystem of merchant silicon. In the case of Linux, Intel, AMD, and customers of ARM deliver the merchant silicon.
A limitation of SDN solutions today is that they are switch-centric and do not extend to the server endpoints, let alone the application interface. Solarflare’s technology is capable of extending an SDN solution from the edge switch all the way to the application interface because we provide a unique server endpoint solution. Our server adapters include kernel bypass via our OpenOnload stack. OpenOnload provides direct access to the application and provides an open control plane that controls data flows directly to the application. This enables some truly unique capabilities in an SDN solution.
Cole: Is it crucial that the entire SDN universe revolve around a single standard like OpenFlow? How would a multi-protocol virtual network function?
Tolley: To mix metaphors, the brave new world of SDN will not be created in seven days and can only come into existence based on robust, open standards.
Arguably the first step toward SDN is the deployment of OpenFlow-enabled devices. OpenFlow is a communications protocol that gives access to the forwarding plane of a network switch or router over the network. Put simply, OpenFlow allows the path of network packets through the network of switches to be determined by software. This separation of the control intelligence from the forwarding allows for more sophisticated traffic management than is feasible using access control lists (ACLs) and routing protocols. This being said, there is more to SDN than just OpenFlow. The Open Networking Foundation has task groups working on the multiple projects such as extensibility, configuration and management, testing and interoperability, architecture and framework, and forwarding abstractions.
Networks of virtual switches are already being built today by customers using the various virtual operating systems on the market from VMware, Citrix, Redhat KVM, etc. The functionality of these networks is primarily packet forwarding and filtering. The promise of OpenFlow and SDN is that the control plane that manages virtual and bare metal switches can be distributed and the controller can be a standalone controller device, a virtual machine in a hypervisor, or embedded in the switch in the Ethernet NIC itself. Having an OpenFlow-capable server adapter and using OpenOnload can extend this capability to the application layer, enabling a true end-to-end SDN.
Cole: What, then, are the most crucial steps the enterprise needs to take now to lay the groundwork for SDN?
Tolley: The network architects at the big enterprises are invited to join the various groups driving standards for software-defined networking. There are also several efforts under way to show the beef. Today, technology leaders at customer and research consortia in the U.S., Europe and Asia are beginning to evaluate vendors in order to build OpenFlow networks for test beds and proof of concept (POC) testing. A key goal of these POCs is to demonstrate that a multivendor OpenFlow network can perform under typical business loads. For example, Solarflare partnered with NEC two years ago to demonstrate an OpenFlow SDN network using Solarflare’s server adapter and NEC’s network switch operating with a common control plane for all devices on the network. This was an early demonstration but showed the promise of this approach.
Therefore, these customers are looking for the tools often lumped in the category of network TAPs to provide precise visibility into network conditions without having to spend money on additional hardware infrastructure that often compromises performance. To put it simply, data center managers cannot improve the performance of systems they cannot measure and they need to prove the performance of these software-defined networks to start building the transition to this brave new world.
To point to some performance analysis tools that are available today, Solarflare has partnered with TS Associates to deliver a sophisticated application-level monitoring and analytics tool. The TS Associates Application Tap for Solarflare delivers insights into the performance dynamics of real-time applications. Solarflare has also partnered its SolarCapture software with Arista's DANZ technology to ensure fine-grained visibility and traffic monitoring across an SDN network. With SolarCapture, any server can be turned into a performance monitoring tool with very little capex investment.