Subject: [Capwap] Entering Image Data has no timeout

From: "Pat Calhoun (pacalhou)" <[email-masked]>
Date: Fri, 16 Nov 2007 15:21:18 -0800

All,

Another issue that I ran across when removing the NeighborDead timer was
that it was being incorrectly used during the transition from Join to
Image Data. It's intent was to allow the AC to timeout if the WTP never
started the image data process. This issue (now Issue 23) is fixed by
having the AC set a timer when it enters the state, and reset the timer
when it receivers the first Image Data Request from the WTP. If no such
packet is ever received, it would cause a failure that would reset the
state machine.

<proposed text>
2.3.  CAPWAP State Machine Definition
[...]

   Join to Image Data (r):  This state transition is used by the WTP and
      the AC to download executable firmware.
[...]

      AC:  This state transition occurs when the AC receives the Image
         Data Request message from the WTP.  The AC MUST transmit an
         Image Data Response message (see Section 9.1.2) to the WTP,
         which includes a portion of the firmware.  The AC MUST start
         the ImageDataStartTimer timer (see Section 4.7).

   Image Data to Image Data (4):  The Image Data state is used by the
      WTP and the AC during the firmware download phase.
[...]

      AC:  This state transition occurs when the AC receives the Image
         Data Request message from the WTP while already in the Image
         Data state, and it detects that the firmware download has not
         completed.  The AC disables the ImageDataStartTimer timer if it
         was enabled.
   Image Data to Reset (o):  This state transition is used to reset the
      DTLS connection prior to restarting the WTP after an image
      download.
[...]

      AC:  The AC enters the Reset state when the image download is
         complete, if an error occurs during the image download process
         or if the ImageDataStartTimer timer expires.

4.7.  CAPWAP Protocol Timers
[...]

4.7.8.  ImageDataStartTimer

   The number of seconds the AC will wait for the WTP to initiate the
   Image Data process.

   Default: 30

</proposed text>

PatC
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