Many equipment vendors use the terms software-defined networking (SDN) and network functions virtualization (NFV) interchangeably. However, these technologies are different and are used in different parts of the network. NFV is virtualizing device functionality, while SDN is developing standard interfaces and orchestration between devices.
SDN was conceived in the campus network. Technology researchers wanted to be able to test applications without having to manually update software on every network device. So, they developed a “programmable” network by separating control and forwarding functions, centralizing control and using well-defined interfaces – application programming interfaces. This concept was then extended to the data center where server virtualization was already implemented. Installations of SDN-enabled equipment have started and are now becoming mainstream in local area networks (LANs).
NFV was developed by service providers in order to accelerate the introduction of new services on their networks. Traditionally, communications service providers (CSPs) have designed proprietary equipment, which has made it cumbersome to quickly provision new services. The ultimate goal of NFV for the transport network is to consolidate network equipment types into standard servers, switches and storage. This simpler equipment would run virtual functions (software) for routers, firewalls and other network functions.
NFV is being standardized in the European Telecommunications Standards Institute (ETSI), while SDN’s initial standardization efforts are in the Open Networking Forum (ONF). The Optical Internetworking Forum (OIF) is also currently standardizing a form of SDN – Transport SDN. These technologies will certainly work together to make an overall programmable network where SDN virtualizes the network and NFV virtualizes the appliances. It’s important to note that SDN really requires a totally new network configuration, while NFV can be implemented on top of existing networks.
The following diagram shows the power of implementing both:
Network structures like this help enable on-demand provisioning, bandwidth-on-demand and video streaming, as well as many other applications.
NFV Roadmap and Impact
The following diagram shows the most likely roadmap for NFV. We are currently in the development stages for migration to common-off-the-shelf (COTS) equipment and virtualized appliances. The next step is putting these functions in a network cloud along with orchestration with SDN and the final step is an agile, on-demand, scalable network:
With the adoption of standard servers, storage and switching that have traditionally been used in LANs, the wide area network (WAN) will transform into a highly available programmable one. Equipment manufacturers need to adjust their network interface devices to enable this functionality. This changes the overall market dynamics. No longer can WAN equipment providers count on getting and keeping customers because they provide a proprietary solution. Companies like HP, Intel and Brocade will now be vying for CSP business that was previously only available to companies like Alcatel-Lucent, Huawei, NEC and other traditional telecom-centric vendors. It’s very interesting to see all of these companies trying to determine where they fit in this new ecosystem. The bottom line is that it’s good for the entire value chain – from component supplier to end user – because services will now be faster, easier and less costly to deliver.