How it works...

Once the request to connect a new NETCONF device is sent, OpenDaylight will set up the communication channel used for managing and interacting with the device. At first, the remote NETCONF device will send its hello-message defining all of the capabilities it has. Based on this, the netconf-connector will download all the YANG files provided by the device. All those YANG files will define the schema context of the device.

At the end of the process, some exposed capabilities might end up as unavailable, for two possible reasons:

1. The NETCONF device provided a capability in its hello-message, but hasn't provided the schema.
2. OpenDaylight failed to mount a given schema due to YANG violation(s).

OpenDaylight parses YANG models as per RFC 6020; if a schema is not respecting the RFC, it could end up as an unavailable-capability.

If you encounter one of these situations, looking at the logs will pinpoint the reason for such a failure.