Subject: [Capwap] Issue 122: Editorial Issues in CAPWAP-01

From: "Pat Calhoun (pacalhou)" <[email-masked]>
Date: Fri, 26 Jan 2007 05:33:48 -0800

Please see the proposed text for the various issues listed below.
Thanks for the comments.

> (1)
> Section: 2.3.1
> Join to Configure (g): 
> 
>  The WTP also starts the ResponseTimeout timer
>          (see ).  (Section 4.5) 
> >>
>  The WTP also starts the ResponseTimeout timer
>          (see Section 4.5).
<PRC> This was fixed a long time ago.

> (2)
> Section: 2.3.1
> Join to Reset (h): This state transition occurs when the WaitJoin
>             Timer expires. 
>       WTP: The state transition occurs when the WTP WaitJoin timer
>          expires, or upon DTLS negotiation failure.
> 
>       AC: Thise state transition occurs when the AC WaitJoin timer
>          expires, or or upon DTLS negotiation failure.
> >>
> contradicts with statement in section 6.2 "
> If the WaitJoin Timer expires prior to reception of the Join Response
>    message, the WTP MUST terminate the handshake, deallocate
associated
>    session state and transition to the Discover state.
> "
<PRC> The WaitJoin timer no longer exists. With the introduction of
DTLS,
the timer was changed to WaitDTLS. That said, the state machine text did
not properly include the case where this timer could expire. The
following
change has been made:
<text>
   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.
</text>

> (3)
> Section 8.6.
>   Change State Event Request
> 
>    The Change State Event Request message is used by the WTP to inform
>    the AC of a change in the operational state.
> 
>    The Change State Event Request message is sent by the WTP when it
>    receives a Configuration Response message that includes a Change
>    State Event message element. 
> 
> >>
> "   receives a Configuration Status Response message that includes a
> Change.."
<PRC> This was fixed a while ago since I can no longer find it.

> (4)
> Section 2.3.1
>    Configure to Image Data (i): This state transition is used by the
WTP
>       and the AC to download executable firmware.
> 
>       WTP: The WTP enters the Image Data state when it successfully
>          comletes DTLS session establishment, and determines that its
>          version number and the version number advertised by the AC
are
>          different.  The WTP transmits the Image Data Request (see
>          Section 9.1) message requesting that a download of the AC's
>          latest firmware be initiated.
> >>
> "download of the AP's latest firmware.." looks better !
> 
<PRC> I have just sent text that included new text to clean this up.
However,
the sentence you are refering to is still problematic. I have made the
following
change (last sentence):
<text>
   Join to Image Data (r):  This state transition is used by the WTP and
      the AC to download executable firmware.

      WTP:  The WTP enters the Image Data state when it receives a
         successful Join Response and determines and the included Image
         Identifier message element is not the same as its currently
         running image.  Further, the WTP also detects that the
         requested image version is not currently available in the WTP's
         non-volatile storage (see Section 9.1 for a full description on
         the firmware download process.  The WTP transmits the Image
         Data Request (see Section 9.1.1) message requesting the start
         of the firwware download.
</text>

> (5)
> Section 2.3.1
> Run to Run (n): This is the normal state of operation
> 
>          Echo Request: The WTP receives an Echo Request message (see
>             Section 7.1), to which it MUST respond with an Echo
Response
>             message(see Section 7.2).
> >>
> "The WTP receives an Echo Response message ..."
> 
>          Echo: The AC sends an Echo Request message Section 7.1 or
>             receives the corresponding Echo Response message, see
>             Section 7.2 from the WTP.
> >>
" The AC sends an Echo Response.."
<PRC> Yes, this was a problem. Find the new text below:
<text>
   Run to Run (5):  This is the normal state of operation.
[...]
      WTP:  This is the WTP's normal state of operation.  There are many
         events that result this state transition:
[...]
         Echo Request:  The WTP sends an Echo Request message
            Section 7.1 or receives the corresponding Echo Response
            message, see Section 7.2 from the AC.
[...]
      AC:  This is the AC's normal state of operation:
[...]
         Echo:  The AC receives an Echo Request message (see
            Section 7.1), to which it MUST respond with an Echo Response
            message(see Section 7.2).

> (6)
>  Run to Reset(o): 
> 
> WTP: The WTP enters the Reset state when it initiates orderly
>          termination of the DTLS connection, or when the underlying
>          reliable transport is unable to transmit a message within the
>          RetransmitInterval timer, see Section 4.5 
> >>
> ".. RetransmitInterval timer and the maximum
>          number of RetransmitCount counter has reached the
MaxRetransmit
>          variable (see Section 4.6).   "
> 
> 
> or;
> 
> " ..is unable to transmit a message within the
>          ResponseTimeout timer, see Section 4.5 " 

Given the new state machine, this is now considerably different.
However,
the text you are referring to had disappeared, and was needed. Please
find the text below:
<text>
   Run to DTLS Teardown (u):  This state transition occurs when an error
      has occured in the DTLS stack, causing the DTLS session to be
      torndown.

      WTP:  The WTP enters this state when it receives one of the
         following DTLS notifications: DTLSAborted,
         DTLSReassemblyFailure or DTLSPeerDisconnect (see
         Section 2.3.2.2).  The WTP MAY decide to tear down the DTLS
         session if it receives frequent DTLSDecapFailure notifications.
         The WTP also transitions to this state if the underlying
         reliable transport's RetransmitCount counter has reached the
         MaxRetransmit variable (see Section 4.6).

      AC:  The AC enters this state when it receives one of the
         following DTLS notifications: DTLSAborted,
         DTLSReassemblyFailure or DTLSPeerDisconnect (see
         Section 2.3.2.2).  The WTP MAY decide to tear down the DTLS
         session if it receives frequent DTLSDecapFailure notifications.
         The WTP also transitions to this state if the underlying
         reliable transport's RetransmitCount counter has reached the
         MaxRetransmit variable (see Section 4.6).
</text> 

Pat Calhoun
CTO, Wireless Networking Business Unit
Cisco Systems
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