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Background

Application Co-existence and Integration Challenges

  • Partitioning of OpenFlow Resources

    1. Every application must have their private flow state space (on every switch)
      1. Flow tables, group table, meter table, cookies
  • Ingress demultiplexing (aka “Table 0 Problem”)
    1. Packets entering the switch have to be directed to the correct application pipeline
    2. Applications cannot simply write ingress flow entries into table 0 without coordination
    3. Need smaller granularity than OF port (e.g. VLAN, VNI, etc)? generalized interface concept
    4. Co-existence of multiple applications on the same interface
    5. Multi-tenancy: Several isolated service instances of the same application
  • Integration/Co-operation of different applications
    1. Control plane: Service APIs between applications
    2. Data plane: Transfer packets between the pipelines of different applications
      1. Take the use of various packet metadata into account!
    3. Each application comes with its own overlay solution

Case-by-Case Approach

  • Chosen approach in ODL Beryllium between SFC, GPB and Netvirt
    1. Partitioning of OpenFlow Resources
      1. Design time coordination between different applications
    2. Ingress demultiplexing (aka “Table 0 Problem”)
      1. All application write into table 0, but the flow entries and priorities have been agreed at design time to avoid unwanted interference
    3. Integration/Co-operation of different applications
      1. Control plane: MD-SAL service APIs between applications?
      2. Data plane: Direct GOTO Table to transfer the packet from one application pipeline to another
  • Analysis
    1. Can lead to an optimal solution for a group of specific applications
    2. Design time coordination needed for every detail
    3. Hard-coded dependencies between applications
    4. Does not scale to many applications

Ingress De-multiplexing

  • Multiple applications writing into table 0 (directly or through an Ingress Manager function)
  • Flow conflict detection mechanisms do not allow for any overlap between flows
  • Overlap (or rather refinement) should be allowed using priorities to disambiguate:
    1. e.g. packets on in_port with certain DMAC to application A, all the rest to application B
  • How can a generic Ingress Manager ensure that there is no semantic conflict between the flows if the simple non-overlap criterion is not sufficient?

Genius Proposal





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