A Framework for NFV Applications

By moving network appliance functionality from proprietary hardware to software, Network Function Virtualization promises to bring the advantages of cloud computing to network packet processing. However, the evolution of cloud computing (particularly for data analytics) has greatly benefited from application-independent methods for scaling and placement that achieve high efficiency while relieving programmers of these burdens. NFV has no such general management solutions. To this end, we present E2 -- a scalable and application-agnostic scheduling framework for packet processing.

SOSP Paper Slides Source Code


E2 is made up of three main system components: the E2 Manager which orchestrates overall operation of the cluster, a Server Agent that manages operation within each server, and the E2 Dataplane (E2D) that acts as a software traffic processing layer beneath the NFs at each server. The E2 Manager interfaces with the hardware switch(es) through standard switch APIs and with the Server Agents.


E2 provides a declarative interface through which the global SDN controller tells each E2 cluster how traffic should be processed. It does so by specifying a set of policy statements that we call pipelets. Each pipelet defines a traffic class and a corresponding directed acyclic graph (DAG) that captures how this traffic class should be processed by NFs.

Dynamic Scaling

E2 provides hooks for NFs to report on their instantaneous load, and the E2D detects overloads based on queues and processing delays. When the E2D detects overload, it splits the overloaded NF instance to lighten the load. This involves placing the new instances, setting up new interconnection state, and considering the affinity requirements of flows, so it is not to be done lightly. Pictured above is the traffic load at an overloaded NF instance and its corresponding new instance with migration avoidance enabled (original NF splits at 2s).

Migration Avoidance

E2 employs a novel migration avoidance strategy in which the hardware and software switches act in concert to maintain flow affinity. This scheme does not require state migration and is designed to minimize the number of flow table entries used on the hardware switch to pass traffic to NF instances

The Team

  • Shoumik Palkar
  • Chang Lan
  • Sangjin Han
  • Keon Jang
  • Aurojit Panda
  • Melvin Walls
  • Christian Maciocco
  • Sylvia Ratnasamy
  • Joshua Reich
  • Luigi Rizzo
  • Scott Shenker