Recently, network operators and data centres have moved towards virtualization of network functions. The partial reason for it goes to their low maintenance and high flexibility when compared to dedicated hardware, which is prone to failures. Moreover, VNFs guarantee savings in CAPEX and OPEX, while running in the fashion of Software as a Service.
When several network functions are chained together to perform some service, they form an SFC. In service function chains, traffic is required to pass through VNFs in a sequential manner only. For instance, if a service deployed by an operator requires traffic to pass through the firewall, load balancer and then WAN acceleration, an SFC will be formed if and only if the flow of traffic happens in such a manner. In a data centre/ telecom network, the same types of VNFs are deployed at different servers, which might be placed in different locations.
Network slicing runs on the principles of SFC, where multiple logical networks are run on top of a single shared physical network. N/W slicing is expected to play a vital role in 5G, where services are divided into logical slices(depending on their requirements) -