Subject: [Capwap] Proposed text for issue 245: State machine timeouts

From: "Pat Calhoun (pacalhou)" <[email-masked]>
Date: Tue, 20 Feb 2007 08:48:26 -0800

Peter pointed out a valid problem, which was introduced when DTLS was
added to the base draft. There must be a way for the AC to disconnect
the session if it does not receive a Join Request after the DTLS session
has been established. Please find the proposed text below.

<text>
2.3.1.  CAPWAP Protocol State Transitions
[...]
   DTLS Connect to Join (n):  This transition occurs when the DTLS
      Session is successfully established.

      WTP:  This state transition occurs when the WTP receives the
         DTLSEstablished notification (see Section 2.3.2.2), indicating
         that the DTLS session was successfully established.  When this
         notification is received, the FailedDTLSSessionCount counter is
         set to zero.

      AC:  This state transition occurs when the AC receives the
         DTLSEstablished notification (see Section 2.3.2.2), indicating
         that the DTLS session was successfully established.  When this
         notification is received, the FailedDTLSSessionCount counter is
         set to zero, and the WaitJoin timer is started (see
         Section 4.6).

   Join to DTLS Teardown (p):  This transition occurs when the join
      process failed.

      WTP:  This state transition occurs when the WTP receives a Join
         Response with a Result Code message element containing an
         error, if the Image Identifier provided by the AC in the Join
         Response differs from the WTP's currently running firmware
         version and the WTP has the requested image in its non-volatile
         memory, or if the WaitDTLS timer expires.  This causes the WTP
         to initiate the DTLSShutdown command (see Section 2.3.2.1).
         This transition also occurs if the WTP receives one of the
         following DTLS notifications: DTLSAborted,
         DTLSReassemblyFailure or DTLSPeerDisconnect.

      AC:  This state transition occurs either if the WaitJoin timer
         expires or if the AC transmits a Join Response with a Result
         Code message element containing an error.  This causes the AC
         to initiate the DTLSShutdown command (see Section 2.3.2.1).
         This transition also occurs if the AC receives one of the
         following DTLS notifications: DTLSAborted,
         DTLSReassemblyFailure or DTLSPeerDisconnect
 
[...]
4.6.17.  WaitJoin

   The maximum time, in seconds, after which the DTLS session has been
   established that the AC will wait before receiving a Join Request.
   This timer must be greater than 30 seconds.

   Default: 60
</text>

Pat Calhoun
CTO, Wireless Networking Business Unit
Cisco Systems
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