difference between NFV and SDN

Network Functions Virtualisation aims to transform the way that network operators architect
networks by evolving standard IT virtualisation technology to consolidate many network equipment
types onto industry standard high volume servers, switches and storage, which could be located in
Datacentres, Network Nodes and in the end user premises, as illustrated in Figure 1. It involves the
implementation of network functions in software that can run on a range of industry standard server
hardware, and that can be moved to, or instantiated in, various locations in the network as required,
without the need for installation of new equipment.

As shown in Figure 1, Network Functions Virtualisation is highly complementary to Software Defined Networking (SDN), but not dependent on it (or vice-versa). Network Functions Virtualisation can be implemented without a SDN being required, although the two concepts and solutions can be combined and potentially greater value accrued.

Figure 1. Network Functions Virtualisation Relationship with SDN

Network Functions Virtualisation goals can be achieved using non-SDN mechanisms, relying on the techniques currently in use in many datacentres. But approaches relying on the separation of the control and data forwarding planes as proposed by SDN can enhance performance, simplify compatibility with existing deployments, and facilitate operation and maintenance procedures. Network Functions Virtualisation is able to support SDN by providing the infrastructure upon which the SDN software can be run. Furthermore, Network Functions Virtualisation aligns closely with the SDN objectives to use commodity servers and switches.

NFV is about the virtualization of function box, like router, firewall, etc; Just put those functions in VMs, but control and data are still together in one box; SDN is about the separation of control plan and data plane of one node.

NFV covers all L2-L7 function boxes; while SDN focus on L2-L3 switches/routers;

SDN and NFV – Working Together?

Let’s look at an example of how SDN and NFV could work together. First, Figure 2 shows how a managed router service is implemented today, using a router at the customer site.

Figure 2: Managed Router Service Today

NFV would be applied to this situation by virtualizing the router function, as shown in Figure 3. All that is left at the customer site is a Network Interface Device (NID) for providing a point of demarcation as well as for measuring performance.

Figure 3: Managed Router Service Using NFV

Finally, SDN is introduced to separate the control and data, as shown in Figure 4. Now, the data packets are forwarded by an optimized data plane, while the routing (control plane) function is running in a virtual machine running in a rack mount server.

Figure 4: Managed Router Service Using NFV and SDN

The combination of SDN and NFV shown in Figure 4 provides an optimum solution:

• An expensive and dedicated appliance is replaced by generic hardware and advanced software.
• The software control plane is moved from an expensive location (in dedicated platform) to an optimized location (server in a data center or POP).
• The control of the data plane has been abstracted and standardized, allowing for network and application evolution without the need for upgrades of network devices.

1, SDN & NFV concept is from SS;

2, map has a summary of key involvers wihtin;