What is Service Chaining?
Service chaining refers to the automated mechanism that enables various network functions (NF)—such as routers, firewalls, and load balancers—to interact and pass packets in the correct sequence. It is used in Software Defined Network (SDN) environments to provide orchestration of network functions. Although service chaining can apply to physical network appliances, the primary focus is on orchestrating Network Function Virtualization (NFV), which virtualizes network functions for greater flexibility.
The standard approach to implementing service chaining is under active discussion within the IETF (Internet Engineering Task Force), which has proposed the Service Function Chaining (SFC) methodology. In SFC, flow-specific tags are added to packets, and these tags dictate packet processing and routing through the network. These tags are referred to as NSH (Network Service Headers). Notably, a demonstration of this method was conducted in February 2015 by six companies, including NTT, Hitachi, and NEC. As of March 2016, however, this approach is still in the testing phase and not yet mature for practical use.
One practical, deployable service chaining solution is the combination of F5 BIG-IQ and an SDN controller. This integration allows for the configuration and automated placement of various network functions provided by F5 BIG-IP along the network path.