1) Send ZDO Leave to ZR parent with ZED's EUI as target
-Pros: Will always succeed (if ZED is still in the child table of ZR and ZR is reachable) with response status, regardless of what ZED's polling rate is.
-Cons: If ZED isn't polling parent regularly, parent's NWK Leave command to child could time out before child gets it, and child gets erased anyway. When child polls next time, parent will tell him to leave and rejoin because it's an non-child end device, so that gets you back to before the ZDO Leave.
2) Send ZDO Leave to ZED with ZED's EUI (or all-zero EUI) as target
-Pros: ZDO response clearly indicates whether ZED received the leave request. No confusion as above with ZED accidentally being told to rejoin.
-Cons: If ZED isn't polling parent regularly, it won't receive this request, so sender needs to be careful about timing of sending the request.
3) Send APS Remove Device command to ZR parent with ZED's EUI as deviceToRemove.
-Pros: APS-authenticated (unlike ZDO messages), so devices (even SE devices) can't choose to ignore this, and it is harder to spoof because it requires APS encryption.
-Cons: Need long address of child and parent for the command. No APS ACK available for APS commands, so can't confirm receipt by the parent. Still may encounter problem where parent deletes child before the child knows it was removed, causing child to rejoin on next poll attempt. Can only be sent by Trust Center. Frequency Agility essentially means a network channel change. The channel change process is governed by a Network Manager device (typically the Coordinator), which changes the channel as decided by the application in response to incoming channel quality notifications.
A node will automatically notify the network manager (NM) when enough of its unicasts fail. Per Zigbee specifications, a report will be sent to the NM if all of the following conditions are met:
- There have been at least 20 attempted transmissions
- One quarter or more have failed
- It has been at least 15 minutes since the last report
For the NM, the process is generally as follows:
- The child node's stack detects the unicast failure and scans and sends a notification to the network manager. This part happens automatically in the stack.
- Your network manager receives the notification in its network manager.
- NM decides whether to change channel and issue a network update.