Overview of OpenFlow 1.3

An OpenFlow switch maintains one or more flow tables, which are used for packet processing. The switch performs the actions listed in the table entry corresponding to the matched flow.

The OpenFlow Controller manages the OpenFlow switch using the OpenFlow Protocol. The OpenFlow Controller can add, delete, or modify flows by getting statistics for ports and flows and other information using the OpenFlow Protocol.

OpenFlow 1.3 architecture

Each flow table maintained in a switch, consists of flow entries sorted by the flow priority. Highest priority flows are at the top of the flow table. Incoming packets are matched against the flow entries starting from the highest priority flow. If there is a match, then flow matching stops, and the set of actions for that flow entry performed. The packets that don't match any flow entry, are either dropped, or sent to the controller.

OpenFlow 1.3 defines three tables:

  • Flow tables
  • Group table
  • Meter table

OpenFlow 1.3 flow table entries

The incoming packets are matched against the multiple tables in the pipeline.

Pipeline processing

In this section:

  1. Flow table entries
    Each flow table entry contains the fields described in the following table.
  2. OpenFlow instructions
    Each flow entry has a set of instructions that are executed when the packet matches the entry.
  3. OpenFlow actions
    Each flow has a set of instructions that are executed when the packet matches the flow as per OpenFlow 1.3 specifications. Each flow can have a maximum of one instruction of each type.
  4. Scaling considerations
    These are the scaling considerations and limitations for the flows and CAM partitions. These considerations are for ICX 6610 and ICX 6450 in mixed stack only.
  5. Multiple controller connections
    An OpenFlow switch may be connected to multiple controllers for reliability. It allows the switch to continue to operate in OpenFlow mode if a controller or controller connection fails. The controllers coordinate the management of the switch amongst themselves to help synchronize controller handoffs.
  6. Asynchronous configuration
    Asynchronous messages may need to be sent to multiple controllers. An asynchronous message is duplicated for each eligible OpenFlow channel, and each message is sent when the respective controller connection allows it.
  7. Supported OpenFlow messages
    The following OpenFlow messages are supported on the Brocade devices.
  8. Output port Normal action
    Output port Normal is a reserved action. Normal action represents the traditional non-OpenFlow pipeline of the device. Normal is a special type of output port included in the actions associated with a flow. When a flow is received from the controller with output port as Normal, the switch processes the matched incoming packet using the local switching or routing.
Parent topic: OpenFlow 1.3