Network operators are working on a new initiative called Network Functions Virtualization (NFV) to reduce their costs while accelerating new service deployments. Instead of buying a proprietary network appliance to run each new task, they want to launch applications (called virtual network functions or VNFs) to run on virtual machines on standard servers.
The ETSI ISG launched an NFV group to foster interoperable products for a broad number of use cases. It has three teams working on the three broad areas: management and orchestration of network services on an NFV infrastructure; the software architecture of the new VNF apps; and the hardware requirements NFV for compute, hypervisors, and networks.
ETSI broke down the job of defining NFV into three areas.
Meanwhile, software defined networking (SDN) is another networking initiative in the works and in early deployment. While NFV is about network equipment virtualization, SDN is about network virtualization. SDN calls for the separation of the control plane from the data plane, making the latter simple and fast, dealing mostly with the media access control and Internet Protocol layers.
An SDN controller has a bird's-eye view of the whole network and can dynamically steer traffic based on statistics gathered from the network. In addition, third-party apps and management tools can run above the SDN controller. In SDN, these applications are network-aware and can communicate their requirements policies to the network.
It remains to be seen how SDN will be integrated into the NFV model (below). Some believe that the orchestration and the management applications can themselves be a VNF, running on one or more VMs. In this case, the OpenFlow protocol is part of the Nf-Vi interface or it can be part of the Vn-Nf interface.
The NFV framework shows interfaces between various functional blocks.
Click here to enlarge.
(Source: ISG NFV)
As a result, both NFV and SDN are synergistic and complementary. When deployed together, network equipment can be built using virtualized servers while the overall network controlled through SDN. The resulting network of NFV equipment can be dynamically reconfigured for different applications and traffic patterns. In addition, the SDN controller can steer traffic from one system to another as needed. A legacy firewall, for example, can be dynamically inserted in the traffic path when network monitoring and statistics show abnormal traffic.
As NFV group develops its specs, it will need to focus on interfaces between functional blocks (shown in the top diagram), as well as interfaces between the hypervisors and computers. The group also must identify gaps that need to be addressed by appropriate standards bodies. Finally, it needs to make a special effort to identify open-source projects for NFV.
Future blogs will discuss the latest efforts to draft NFV requirements, implementation concepts with and without SDN, and challenges in scalability and reliability.
ó Nabil Damouny is Vice Chair of the Market Education Committee at the Open Networking Foundation that manages SDN, and the editor of the compute-storage domain for ETSI NFV. He is also Senior Director of Strategic Marketing at Netronome.