Document difference between `port.created` and `interface.created` events

[cmagnobarbosa]

Today Kytos uses two events (port.created and interface.created) when a port on the switch is created, but the difference between these events is not clear.

• https://github.com/kytos/of_core/blob/master/main.py#L462L485

Therefore, additional research is needed.

Additional information from OpenFlow spec:

OpenFlow ports are the network interfaces for passing packets between OpenFlow processing and therest of the network. OpenFlow switches connect logically to each other via their OpenFlow ports. An OpenFlow switch makes a number of OpenFlow ports available for OpenFlow processing.

The set of OpenFlow ports may not be identical to the set of network interfaces provided by the switch hardware,some network interfaces may be disabled for OpenFlow, and the OpenFlow switch may define additional OpenFlow

[italovalcy]

Hi Carlos, for me, it looks like the proper name for the event would be "port.created" if we consider the OpenFlow specification. This way, whenever we have a logical port (e.g., link aggregation), which is not a physical network interface in the switch, Kytos will notify it properly. After saying that, from the Kytos modeling perspective, it looks like the event is referring to Internet kytos data model, and as so, IMHO, "interface.created" is the most appropriate one.

[italovalcy]

@cmagnobarbosa when you mentioned that kytos generate both port.created and interface.created was it because of handle_port_desc() call?

• https://github.com/kytos/of_core/blob/master/v0x04/utils.py#L101-L138

In my understanding, what happens is: when the switch first connects to Kytos, Kytos request the PORT_DESC, which generates the port.created event. Then, there is the asynchronous PORT_STATUS message, which of_core handles and generate a interface.created event. So far, they seems to be correct. I would only say that the PORT_DESC should also generate an interface.created event, even because it in fact calls the switch to create the interface (https://github.com/kytos/of_core/blob/master/v0x04/utils.py#L127)