Service Function Chains Using Virtual Networking

Document Type Replaced Internet-Draft (individual)
Last updated 2015-04-20 (latest revision 2014-10-17)
Replaced by draft-fm-bess-service-chaining
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


This document describes how service function chains (SFC) can be applied to traffic flows using routing in a virtual (overlay) network to steer traffic between service nodes. Chains can include services running in routers, on physical appliances or in virtual machines. Service chains have applicability at the subscriber edge, business edge and in multi-tenant datacenters. The routing function into SFCs and between service functions within an SFC can be performed by physical devices (routers), be virtualized inside hypervisors, or run as part of a host OS. The architecture uses a controller to calculate and install routes to implement an SFC, based on a topological model of the chain and knowledge of the network addresses that should pass through the chain. An advantage of the approach is that SFCs can be implemented without alteration to today's BGP standard, and without change to the current operation of routers. Service chains need to support load balancing between network functions, and symmetric forward and reverse paths are required when stateful services are involved. This document shows how these requirements can be met by using VRFs at the ingress and egress of each service instance and by performing load balancing after the egress of each service as part of the routing function.


Stuart Mackie (
Bruno Rijsman (
Maria Napierala (
Diego Daino (
Diego Lopez ( (
Walter Haeffner (

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)