HP VAN SDN Controller Administrator Guide v3

multiple SDN applications attempting to act on the same packets. In addition, many environments

make it difficult to trace the origin of flow modification requests installed in switches.

The HP VAN SDN Controller uses OpenFlow classes to dynamically manage the priorities of the

OpenFlow rules being deployed to the network, thus enabling applications to execute their business

logic without impacting on each other.

1. For each class of flow modification message the application can send, the application must

of that class to the switches. The OpenFlow class must specify the types of match fields, types

of actions, and (optionally) the relative position (higher than or lower than) for this class with

respect to other flow classes.

2. The controller adds a unique base cookie to be used with each future flow modification to be

validated against this OpenFlow class, and assigns an actual priority for the OpenFlow class.

This actual priority is based on the logical priorities of all of the OpenFlow classes of all the

applications that are registered with the controller.

3. When the application sends a flow modification message, it associates the match and action

with an OpenFlow class and, instead of providing an actual priority, the application provides

a logical priority and a cookie that is derived from the base cookie of the OpenFlow class.

4. Before sending the flow table modification message to the switch, the controller evaluates the

requested flow modification against the registered OpenFlow classes and replaces the logical

priority provided by the application with an actual priority.

In addition to enabling the controller to manage priorities for multiple applications, OpenFlow

classes enable the controller to validate flow modification requests an application makes against

a set of expected flow modification requests. This capability means that the behavior of an

application must match the intent that the application disclosed when it registered with the controller:

• The flow match must contain exactly the fields and field types that were disclosed when the

application registered with the controller. The controller validates field types but not field value.

• The action or instruction must fall into the category that was disclosed during registration.

An action is classified into one of the following categories:

FORWARD

DROP

PROCESS

STEAL

COPY

• The upper 16 bits of the flow modification cookie must match the upper 16 bits of the base

cookie that was issued during registration.

50 SDN Controller Console