Forwarding Abstractions

CHAIR: Curt Beckmann
VICE CHAIR: Johann Tonsing
EDITOR: Ben Mack-Crane

forwarding-abstractionOpenFlow® Standard versions up through 1.3 describe a framework in which controllers request switch forwarding behavior step-by-step (flowmod-by-flowmod) at runtime. The Hardware Abstraction Layer (HAL) must be capable of mapping individual flowmods on-the-fly to the underlying hardware platform.

The Forwarding Abstractions working group (FAWG) is evolving the HAL specifications to enable pre-run time description of switch-level behavioral abstraction to simplify the implementation process of the OpenFlow® Standard and improve the flexibility of target HALs.

Recent achievements and new goals include:


  • Wrote a draft architecture document, “published” on the ONF wiki.
  • Developed a detailed example of a specific TTP that supports basic switching and routing, as well as L2 and L3 multicast and Layer 3 ECMP.
  • Developed a draft negotiation protocol for incorporation into the OF-Config 1.2 protocol. We have worked with members of CMWG to develop a Yang data model to be compatible with the NETCONF-oriented OF-Config protocol.
  • Worked with the Testing and Interoperability work group to confirm that TTPs will add significant value toward ensuring interoperability between devices that are compatible with the OpenFlow® Standard.
  • Now documenting the details of our example TTP, along with the “methodology” (rules) that will enable any ONF member to create additional TTPs. In addition, we have begun to investigate how we will prototype our framework as part of open source projects.
  • Drafted Table Type Pattern (TTP) Framework, including:
    • TTP language specification
    • Sample TTPs
    • NDM negotiation scheme based on OF-Config1.2
    • Initiated at TTP project as part of OpenDaylight controller
  • The TTP framework adheres to the following principles:
    • “Traditional” OpenFlow® still available within TTP framework
    • OpenFlow® adoption on software forwarding targets not impacted
    • TTPs simplify assessment of product interoperability
    • Support for Member-owned TTPs to speed adoption
  • Publish TTP Spec

Goals for 2014

  • Draft White Papers with the help of the MEC (target)
  • Develop additional TTP development aids (ongoing)
    • Technical Recommendations for TTP development
    • Suggested TTP development tools
    • Sample TTPs
  • Work with other WGs to define TTPs (ongoing)
  • Revise and update charter