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How coordinator recognizes Router that rejoins network?

shahar shahar
Intellectual 620 points
Other Parts Discussed in Thread: CC2430

I had an experinent.
I'd just say for background that I own a CC2430 coordinator and routers.

I had a router to join for the first time to network, and then I only changed the router's MAC Address, and wanted to see if it will rejoin network or will need to join again like it was never on network before.

The router has rejoined network, meaning the Coordinator recognized the Router by another parameter instead of the its MAC Address.

What are the paramters which the coordinator uses to recognize router that has been once on network before?

Thank you very much.

  • 0
    Intellectual 620 points

    Could anyone help me please regarding this issue?

    Thank you very much.

  • 0
    Expert 1075 points

    Hello

    Let me try to understand your experiment by asking some questions:

    1) How do you change the MAC address? Do you change the code and re-program the device?

    2) Do you restart the device after changing the MAC address?

    3) Have you verified that the MAC address got changed; e.g. by reading it out again?

    4) Are you using the NV_init orNV_restore options (if you use them the relevant network information like short address will be saved and re-used when re-starting the device)?

    5) Did you look at a sniffer log to see the traffic in the air? Does the router send a new association request after restarting it? If yes what are the replies?

    6) What exactly do you mean with " Coordinator recognized the Router "?

    Normally a router that has a short address will not need/do a re-join. It can exist without a coordinator after it has joined a network and got determined a PAN ID and a short address.

    If you restart a router and it has nothing to send (or route from others or its children) it will not send anything, so I wonder why you say the coordinator "recognizes" the router. It will of course communicate with all devices that use the correct PAN ID (unless security is used).

    - LL -

  • 0
    Intellectual 905 points

    It joins the n/w with PAN ID and Channel also. After joining it'll get a short address. How did u change it's MAC address? I think  its not possible change and assign a new address for the end devices. I'm also getting the questions like Lucky Luke!! Let me know how u r changing the mac address.

    Pandit

  • 0 in reply to Pandit
    Intellectual 620 points

    I changed the MAC address of the device using the Flash programmer SW which enables to READ the MAC address and WRITE a new MAC address into the device.

    Could you ellaborate please about the PAN ID?

    1. How many bytes is this ID?

    2. Who gives the router its PAN ID? is the the COORD which gives it to the router?

    3. Once the router receive its PAN ID, does it stay permanent, or can this value change each time the router rejoins network?

    4. How can I know what is the PAN ID of the router?

    Thank you very much.

  • 0 in reply to LuckyLuke
    Intellectual 620 points

    To LuckyLuke:

    1. I use the flash programmer SW.

    2. Yes I do.

    3. Yes I read it again.

    4. Yes I use them so when router has a reset, it remembers its network he has joined before the reset occured and therefore it rejoins it after reset.

    5. There is a CLUSTER that is sent from router to COORD every time interval in order to let the COORD know that the router is still connected.

    6. I meant that after the router has joined for the first time to COORD's network, than each time the router is rising again (after reset or power-up), the COORD lets the router to rejoin automatically to network.

  • 0 in reply to shahar shahar
    Expert 1075 points

    Howdy!

    Sorry for the delay! I had to chase the Dalton brothers! To compensate I use some more time in the following....

    Thanks for the additional information.

    It looks to me like you still are missing some details about how ZigBee works. Have a look at the ZigBee material on the following page, which I find very useful:

    http://tiexpressdsp.com/index.php?title=Low_Power_RF_Solutions_Workshop#Workshop_Contents

    especially:  http://tiexpressdsp.com/images/8/8a/08_-_ZigBee_Stack.pdf pages 12-18.

    PAN ID

    The PAN ID is the identifier of the network that you are establishing; i.e. all nodes that are communicating in a ZigBee network use the same PAN ID. If you follow a sniffer log (e.g. using the http://focus.ti.com/docs/toolsw/folders/print/packet-sniffer.html) you can see that the packets flying by always have a destination PAN ID, destination short address, and a source short address.

     

    The PAN is as mentioned above identifying the Network the message is sent in. The destination is the source address of the node that should receive the message and the source address is the address of the sender.

    The PAN ID is set by the coordinator when starting up the network (see f8wconfig.cfg file):

    /* Define the default PAN ID.
     *
     * Setting this to a value other than 0xFFFF causes
     * ZDO_COORD to use this value as its PAN ID and
     * Routers and end devices to join PAN with this ID
     */
    -DZDAPP_CONFIG_PAN_ID=0xFFFF

     

     Answer to what you are seeing (if I understand your info correctly):

    When you establish your network with a coordinator and a router the following happens:

    The coordinator determines the PAN ID and uses the short address 0x0000. Then the router is turned on and joins the network and receives a short address (assigned by the coordinator); e.g. 0x0001. Then your application starts sending periodic messages to the coordinator (I guess you program it to send to 0x0000?).

    If you now turn off the router and only change its IEEE address it will at power on use the NV restore functionality (as you wrote that you use it); i.e. it will remember the network (PAN ID) it was on and it will use again the same short address; i.e. it does no new association and hence, the coordinator does not know about the changed IEEE address. If you do not use the NV restore functionality it will join the network as a new device and get a new short address (as it has a different IEEE address, which is sent in the association request, hence the coordinator knows about the change). However, if you again send messages to the short address 0x000 periodically they should also arrive.

    Hope you now manage to resolve your questions.

    -LL-