An implicit assumption behind some of the Lowpan discussions is that, with many nodes, there will be little human interaction apart from an initial InstallationProcess.
This InstallationProcess may be a good time to create both application assocations and security associations. It may also be used for fixing link layer and network layer (IP) attributes, where this is necessary.
The InstallationProcess may use special installer devices, or the installation may be limited to something like a single button that can be pressed on the device to be installed. While the details of the installation UI don't matter to 6lowpan, the way that devices learn their parameters does have a bearing on the protocols we use to maintain their state, including NeighborDiscovery.