Service Function Chaining Extension for OpenStack Networking

Service Function Chaining Extension for OpenStack Networking

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Service Function Chaining API

This project provides APIs and implementations to support Service Function Chaining in Neutron.

Service Function Chaining is a mechanism for overriding the basic destination based forwarding that is typical of IP networks. It is conceptually related to Policy Based Routing in physical networks but it is typically thought of as a Software Defined Networking technology. It is often used in conjunction with security functions although it may be used for a broader range of features. Fundamentally SFC is the ability to cause network packet flows to route through a network via a path other than the one that would be chosen by routing table lookups on the packet’s destination IP address. It is most commonly used in conjunction with Network Function Virtualization when recreating in a virtual environment a series of network functions that would have traditionally been implemented as a collection of physical network devices connected in series by cables.

A very simple example of a service chain would be one that forces all traffic from point A to point B to go through a firewall even though the firewall is not literally between point A and B from a routing table perspective.

A more complex example is an ordered series of functions, each implemented in multiple VMs, such that traffic must flow through one VM at each hop in the chain but the network uses a hashing algorithm to distribute different flows across multiple VMs at each hop.

This is an initial release, feedback is requested from users and the API may evolve based on that feedback.


  • Creation of Service Function Chains consisting of an ordered sequence of Service Functions. SFs are virtual machines (or potentially physical devices) that perform a network function such as firewall, content cache, packet inspection, or any other function that requires processing of packets in a flow from point A to point B.
  • Reference implementation with Open vSwitch
  • Flow classification mechanism (ability to select and act on traffic)
  • Vendor neutral API
  • Modular plugin driver architecture
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