Orphan scans

When an end device comes up from a power cycle, it performs an orphan scan to verify it still has a valid parent. The device sends the orphan scan as a broadcast transmission and contains the 64-bit address of the end device. Nearby routers and coordinator devices that receive the broadcast check their child tables for an entry that contains the end device's 64-bit address. If the devices find an entry with a matching 64-bit address, they send a coordinator realignment command to the end device that includes the 16-bit address of the end device, 16-bit PAN ID, operating channel, and the parent's 64-bit and 16-bit addresses.

If the orphaned end device receives a coordinator realignment command, it joins the network. Otherwise, it attempts to discover and join a valid network.