Step-by-Step Migration To SDN...And Beyond
If 2012 was about establishing a foundation, then 2013 is about accelerating deployment, so that more businesses can achieve the advantages.
Software Defined Networking (SDN) is a disruptive development whose time has come. It breaks open the closed, proprietary world of networking hardware and replaces it with superior functionality enabled by software and managed by IT. Google has already implemented the technology over its intercontinental WAN.
There is a robust business case for migrating to SDN, detailed in an earlier article. In a nutshell, SDN takes networking out of the rigid, mainframe-computing model of the '60s and propels it into an era of network virtualization in which computing and storage resources can be orchestrated by IT. The introduction of a centralized controller allows a Web portal to provide a single logical view of the whole network and thereby a single point of management.
The question for enterprises is becoming when and how to move forward, not if. How to embrace this new technology and migrate seamlessly to a virtual network architecture?
It's clear that forklift upgrades are not an option: it is not feasible to migrate to a centralized SDN framework in one step. Instead, migration will normally entail transitioning to a hybrid architecture that enables a traditionally configured network to provide SDN features. Extreme Networks talks about segments or sections of the network moving to a model based on SDN "islands" that interoperate with traditional networks and indeed work in unison. Dell talks about a new type of network virtualization, one that delivers low-cost private cloud solutions to enterprise data centers. And they emphasize that SDN has the potential to drive the next generation of IT services.
Right now, IT departments are trying to understand how SDN can be deployed and used in conjunction with a traditional network. A key enabler to understanding this migration is for network switches to run in a hybrid mode, i.e. run in both OpenFlow and traditional mode. This can be realized by partitioning the switch so that certain traffic can be forwarded using traditional technologies and certain traffic is forwarded based on rules programmed using SDN technologies such as OpenFlow.
That view comes from Extreme, an Ethernet switch vendor, and there is nothing intrinsically wrong with vendor-centric strategies. The company is an established player that supports OpenFlow/OpenStack, which are de facto standards (see "How Software Defined Networking Will Change Communications"). Dell, on the other hand, is a relatively new player and therefore they do not come with any legacy routers and switches; this allowed them to start with a clean sheet of paper. And on yet another hand, Cisco is taking a defensive position against the possibility that SDN technology could disrupt their leading role in switching and routing.
It's clear that virtual network architectures (VNA) should have a network virtualization overlay--one that encompasses the hypervisor computer environment of major players like Microsoft, VMware and Citrix as well as OpenStack, the SDN open source cloud operating system. Figure 1 is a somewhat simplistic schematic, but it illustrates Dell's top-down, holistic approach. The idea is to deliver the networking benefits and features via modular building blocks, thereby making it easy to access the compelling business benefits without forklift upgrades or complex integration.
Figure 1. Dell's top-down holistic approach is enabled by a Virtual Network Architecture: a framework that provides an evolutionary path leading from legacy networking technologies to OpenFlow and beyond to next-generation SDN applications and services.
Next page: Google's SDN WAN