rfc1934.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

   +---------------+---------------+
   |      array of characters      |
   |               .               |
   |               .               |
   |               .               |
   +---------------+---------------+

   Figure 18: Remote Management Transmit Request

   A message sent from slave to master, conveying output to be output on
   the master's display.

   Character count:
           Number of characters to process.
           2 octets fixed length

   array of characters:
           Array of characters to process.

3.3.15. REMOTE_MGMT_TX_RSP Message Format

   This message is used to acknowledge remote management transmit
   requests.  The slave may send the next transmit request once this
   message has been received.

   +---------------+---------------+
   |         Message type          |
   |          0x0000000f           |
   +---------------+---------------+

   Figure 19: Remote Management Transmit Response

   There are no data fields associated with this message.






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3.3.16. CLEAR_REQ Message Format

   A message sent to initiate a friendly shutdown of an  MP+ link.  The
   sender will stop sending data immediately.  The receiver of the
   message will also stop sending user data and start a clean shutdown
   of all NCPs and the LCP of each member link of the bundle.  When the
   last member link terminates, the session is completely closed.

   +---------------+---------------+
   |         Message type          |
   |          0x00000010           |
   +---------------+---------------+

   Figure 20: Clear Request

   There are no data fields associated with this message.

3.4. Events

   The MP+ state machine is event driven. Reception of an event triggers
   an action and possibly a state change. The events processed by the
   MP+ state machine can be roughly classed into two types:

      Events that originate within the unit, e.g. notification that a
      call has cleared, an  MP+ session may be started, etc.

      Events that originate with the reception of an  MP+ control
      message from the peer unit.

   Both types are processed by the state machine in the sequence they
   occurred. The events processed are:

   MP+START_SESSION:    Notification from PPP/MP that an
                        MP+ session is starting.

   MP+SESSION_DOWN:     Notification from the error-control
                        layer that end-to-end connectivity
                        has been lost and control messages can
                        not be delivered.

   MP+SESSION_TERM:     Session termination notification from
                        PPP/MP.  This event is not sent until
                        the last channel of a multi-channel
                        session is cleared.

   MP+TIMER_EXPIRED:    Timers are used in various states and
                        sub-states.  This event is signaled whenever
                        a timer expires.



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   MP+CALL_COMPLETE:    A call placed during an add request has
                        completed.  The call may have succeeded or
                        failed.

   MP+UTILIZATION:      Notification from MP/PPP that link
                        utilization has crossed a threshold and that
                        channels may need to be added/removed.
                        (The number of channels to add/remove will be
                         passed with the notification).

   MP+RX_VERSION_REQ:   A Version Exchange request message has
                        been received from the peer.

   MP+RX_VERSION_RSP:   A Version Exchange response message has
                        been received from the peer.

   MP+ADD_REQ:          An Add request message has been received
                        from the peer.

   MP+ADD_RSP:          An Add response message has been received
                        from the peer.

   MP+ADD_COMP:         An Add Complete message has been received
                        from the peer.


   MP+REMOVE_REQ:       A Remove request message has been received
                        from the peer.

   MP+REMOVE_RSP:       A Remove response message has been
                        received from the peer.

   MP+REMOVE_COMP:      A Remove Complete message has been received
                        from the peer.

   MP+RX_RM_REQ:        A Remote Management request has been received
                        from the peer.

   MP+RX_RM_RSP:        A Remote Management response has been received
                        from the peer.

   MP+RX_RM_RX_REQ:     A Remote Management Receive Request has been
                        received from the far end.

   MP+RX_RM_TX_REQ:     A Remote Management Transmit Request has
                        been received from the peer.




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RFC 1934                Multilink Protocol Plus               April 1996


   MP+RX_RM_TX_RSP:     A Remote Management Transmit Response has
                        been received from the peer.

   MP+RX_CLEAR:         A request to shut down the session has been
                        received from the peer.

   MP+CLOSE_REQ:        A Close Request message has been received
                        from the peer.

   MP+CLOSE_RSP:        A Close Response message has been received
                        from the peer.

   MP+START_RM          Request to start a remote management session
                        with this station being the master.

   MP+SEND_RMS:         Request to send data to a remote management
                        master from a slave.

   MP+SEND_RMM:         Request to send data to a remote management
                        slave from a master.

   MP+RECV_RMM:         Request to send an ack to a remote management
                        slave for data received from the slave.

   MP+STOP_RM:          Request to stop a remote management session.

3.5. State Machine

3.5.1 States

   To ease readability and understanding the major states are considered
   as separate state machines, each having two to four sub-states. The
   sub-states are named by the letters, A, B, C, and D. State
   information is maintained for every interface.

   The major states are:

   MP+STATE_INITIAL: The state of an unused session. Session table
                     entries are intialized to this state at startup
                     and return to this state when sessions are
                     terminated.

   MP+STATE_IDLE:    The state of an active session that is not
                     performing any MP+ function.

   MP+STATE_ADD:     The state of a session when an add transaction is
                     in progress.




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   MP+STATE_REMOVE:  The state of a session when a remove transaction is
                     in progress.

   MP+STATE_CLOSE:   The state of a session that is in the process of
                     being closed.

   State transitions are triggered by the reception of an event.  Tables
   2 through 6 contain the state tables for the major states.  All state
   tables use the following symbols.

        -       No action

        *       Stay in same state

        +       Target state is defined by the action taken

        **      An error has occurred, log an error message but no
                state change.

   States and sub-state transitions are noted as state:sub-state, e.g.,
   initial:A.  Alternative transitions are listed on separate lines.

3.5.2 Common Actions

   Some actions are common to all states, they are defined here.

Error Close Action

        Called to close a session when an error occurs. Actions are:

        [1]  Stop timer if running.

        [2]  Log an error message.

        [3]  Close the MP+EC layer for this session.

        [4]  Close MP for this session

        [5]  Clean up, restore state variables to their initial state.

Term Action

        Processed when a MP+SESSION_TERM event occurs in most states.
        Actions are:

        [1]  Stop timer if running.

        [2]  Close the  MP+EC layer for this session.



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RFC 1934                Multilink Protocol Plus               April 1996


        [3]  Call the passed termination callback function if not null.

        [4]  Clean up, restore state variables to their initial state.

Ignore Action

        We don't care about this event in this state.  Do nothing.

Timer Action

        This action is called when a timer expires in one of the on-line
        states. The timer is used to implement add and remove locks.  A
        lock is set when an add or remove fails and is not cleared until
        a bandwidth change or the timer expires. This keeps us from
        retrying add's and subtracts until there is a likelyhood that it
        will succeed.

        [1]  Check add lock flag.

                [1] If set an add lock occured last timeout period so
                triple the timeout value (to a max of 81 minutes).

                [2] If not set restore the timeout value to its initial
                value of one minute.

        [2]  Clear the add lock flag.

        [3]  Clear the remove lock flag.

        [4]  Restart the retry timer.

Enter Remove [local] Action

        The local unit is initiating a remove transaction. The desired
        bandwidth is given.

        [1]  Restart the idle timer.

        [2]  Calculate number of channels to remove (difference between
        number in use and number in desired).

        [3]  Build and send a remove request and send to remote.

        [4]  Go to REMOVE:A.







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Enter Remove [remote] Action

        The remote unit is initiating a remove transaction. The incoming
        message contains the number of channels to remove.

        [1]  Restart the idle timer.

        [2]  Request the number of channels required. If greater than the
        number available after removing the number of channels indicated
        in the incoming message reduce the number of channels to remove
        and set a remove lock.

        [3] Build a remove response message indicating the number of
        channels we will allow the requester to remove and send to the
        remote.

        [4]  Go to  REMOVE:B.

Enter Add [local] Action

        The local unit is initiating an add transaction.  We are given
        the number of channels desired.  The steps are:

        [1]  Restart the idle timer.

        [2]  Calculate number of channels to add (difference between
        number desired and number in use).

        [3]  Reserve number of channels, retrieving their phone numbers.

        [4]  If number of channels reserved less than the number desired
        set an add lock.

        [5]  If number of channels reserved greater than zero.

                [1] Build an add request. If the answerer the request
                includes the phone numbers for the caller to dial.

                [2] If caller, go to ADD:A.

                [3] If answerer, go to ADD:C.

        [6]  Go to  IDLE state.








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RFC 1934                Multilink Protocol Plus               April 1996


Enter Remove [remote] Action

        The remote unit is initiating a remove transaction.  The
        incoming  message contains the number of channels to remove.

        [1]  Clear the remove lock.

        [2]  Restart the idle timer.

        [3]  Request the number of channels required.   If  greater
        than the number available after removing the number of
        channels indicated in the incoming message reduce  the
        number of channels to remove.

        [4]  Build  a remove response message indicating the number
        of channels we will allow the requester to remove  and
        send to the remote.