Other Changes

There is a complete list of other changes we have made to upgrade the base software switch from OpenFlow 1.1 to OpenFlow 1.3. Whereas these other changes are important, their implementation demanded less effort than the implementation of changes described in previous subsections. For this reason, we will list and comment on them briefly:

• Table Miss: Previous behavior of OpenFlow switches on non matching packets were defined by configuration flags. OpenFlow 1.3 removes these flags and defines table-miss flow entry. This entry is an all field matching with the lowest possible priority. Table miss support implementation required the removal of code to handle the old behavior. In addition, in the case of a table-miss entry with an action to output the packet for the controller, the switch sends the packet-in message with a reason of type OFPR_NO_MATCH.

• Rework Tag Order: The order of the supported protocols' tags, pushed by an OpenFlow action, was dictated by the specification. In OpenFlow 1.3, tags do not have a right order and should be pushed in the outermost possible position. In the code, these features were reflected by deletion of old restrictions and right adjustment of the tag order.

• Addition of MPLS BOS and PBB fields: The MPLS Bottom of the Stack (BOS) field and support for the Provider Backbone Bridge Protocol (PBB) was quite easy to implement thanks to the Packet Parser design, described in the subsection \ref{pktparser}. PBB support also included actions to push and to pop tags in a packet. These actions are similiar to MPLS and VLAN push and pop, thus implementation for PBB followed a workflow similar to the mentioned protocols.

• Duration for stats: Old versions included the time of existence only for flow entries statistics. OpenFlow 1.3 introduces a duration field for meter, port, queue and group statistics and they are supported by the software switch.