Making the Business Case for SDN - Page 2
What are the capital and operational benefits of software defined networking, and how is the enterprise to know if it's getting its money's worth?
Overlay, White Box or Custom Hardware: The Three Routes to SDN
In the software-defined world, network architectures will be about as diverse as today's physical infrastructure. Every enterprise will have a unique set of requirements that calls for custom solutions. The difference is that these idiosyncrasies will be much easier to implement in software than in hardware.
For the moment, there are three distinct deployment models on which these software architectures will be built: overlay technologies on existing infrastructure, vendor-specific solutions using customized ASICs, and white box deployment on commodity hardware.
Selecting one of these options will require a thorough evaluation of current network capabilities and future goals, and it isn't entirely clear whether any of them will provide optimal service, given that all we have to go on at this point is vendor claims.
VMware, for instance, views SDN from an all-software perspective, which means it can inhabit a wide range of hardware configurations and allow policies and services to extend all the way to the hypervisor, which the company says provides a high degree of operational flexibility.
"We call it 'microsegmentation,'" said Rod Stuhlmuller, director of product marketing at VMware's Network and Security unit. "We can segment [network control] all the way down to the virtual interface on the app, which allows us to make changes centrally and push them out to whatever virtual instances they are associated with."
Naturally, a company like Cisco says there are holes in this approach.
"There are much greater opportunities once you have hardware and software working together," said Cisco Distinguished Engineer Jon Woolwine. "Eventually, I'm going to want to have control of the network infrastructure that supports SDN, and to do that you'll need visibility and the ability to troubleshoot. If you are blind to that piece of the infrastructure and you are unable to control it, not only won't you be able to overcome things like hardware dependencies, but there might be opportunities for efficiency and optimization you might miss."
The question, though, is whether you need a customized ASIC found in hardware like that offered by Cisco and Juniper. If you don't, you might instead adopt the lower-cost solution of white box hardware for simple packet forwarding so that performance issues can be addressed through automated load balancing and other functions. In the latter case, expect to see a high degree of standardization emerge across a range of hardware and software systems. This standardization will be needed not only to simplify the deployment process, but also to ensure that network changes can be implemented immediately across the now highly integrated infrastructure.
In all likelihood, it's a debate that won't be settled until the enterprise gets some real SDN experience under its belt.
Arthur Cole covers networking and the data center for IT Business Edge. He has served as editor of numerous publications covering everything from audio/video production and distribution, multimedia and the Internet to video gaming.