rfc1987.txt

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Newman, et. al.              Informational                     [Page 15]

RFC 1987              GSMP Protocol Specification            August 1996


   If the virtual channel connection specified by the Input Port, Input
   VPI, and Input VCI fields already exists, but the output branch
   specified by the Old Output Port, Old Output VPI, and Old Output VCI
   fields does not exist as a branch on that connection, a failure
   response must be returned with the Code field indicating, "The
   specified branch does not exist." The connection state of the switch
   must not be modified in this case.

   If the virtual channel connection specified by the Input Port, Input
   VPI, and Input VCI fields does not exist, a failure response must be
   returned with the Code field indicating, "The specified connection
   does not exist." The connection state of the switch must not be
   modified in this case.

   The behavior is undefined if the output virtual channel specified by
   the New Output Port, New Output VPI, and New Output VCI fields is
   already in use by any connection.

   A failure response will be returned if the switch is unable to
   establish the specified branch or if there is an error in any of the
   fields of the request message. If a failure message is returned the
   state of the switch must not have been modified by the request
   message.

4. Port Management Message

   The Port Management message allows a port to be brought into service,
   taken out of service, looped back, or reset. Only the Bring Up and
   the Reset Input Port functions change the connection state
   (established connections) on the input port. Only the Bring Up
   function changes the value of the Port Session Number. If the Result
   field of the request message is "AckAll" a success response message
   must be sent upon successful completion of the operation. The success
   response message must not be sent until the operation has been
   completed. The Port Management Message is:

      Message Type = 32

   The Port Management message has the following format for the request
   and success response messages:











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RFC 1987              GSMP Protocol Specification            August 1996


    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Version    | Message Type  |    Result     |     Code      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Transaction Identifier                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                             Port                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Port Session Number                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Event Sequence Number                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Event Flags  |   Duration    |          Function             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Port
             Gives the port number of the port to which the message
             applies.

   Port Session Number
             Gives the current port session number for the port. If the
             Port Session Number in the request message does not match
             the current port session number of the port indicated by
             the Port field of the request message, a failure response
             must be returned with, "Invalid port session number,"
             indicated in the Code field. If the specified function
             requires a new Port Session Number to be generated the new
             Port Session Number must be given in the success response
             message.  The Port Session Number must be generated using
             some form of random number.

   Event Sequence Number
             In the success response message gives the current value of
             the Event Sequence Number of the switch port indicated by
             the Port field. The Event Sequence Number is set to zero
             when the port is initialized and is incremented by one each
             time an asynchronous event is detected on that port that
             the switch would normally report via an Event message. If
             the Event Sequence Number in the success response differs
             from the Event Sequence Number of the most recent Event
             message received for that port, events have occurred that
             were not reported via an Event message. This is most likely
             to be due to the flow control that restricts the rate at
             which a switch can send Event messages for each port. In
             the request message this field is not used and should be
             set to zero by the sender and ignored by the receiver.




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RFC 1987              GSMP Protocol Specification            August 1996


   Event Flags
             Field in the request message is used to reset the Event
             Flags in the switch port indicated by the Port field. Each
             Event Flag in a switch port corresponds to a type of Event
             message. When a switch port sends an Event message it sets
             the corresponding Event Flag on that port. The port is not
             permitted to send another Event message of the same type
             until the Event Flag has been reset. If the Function field
             in the request message is set to "Reset Event Flags," for
             each bit that is set in the Event Flags field, the
             corresponding Event Flag in the switch port is reset.

             The Event Flags field is only used in a request message
             with the Function field set to "Reset Event Flags." For all
             other values of the Function field, the Event Flags field
             should be set to zero in the request message and must be
             ignored by the receiver. In the success response message
             the Event Flags field must be set to the current value of
             the Event Flags for the port, after the completion of the
             operation specified by the request message, for all values
             of the Function field. Setting the Event Flags field to all
             zeros in a "Reset Event Flags" request message allows the
             controller to obtain the current state of the Event Flags
             and the current Event Sequence Number of the port without
             changing the state of the Event Flags.

             The correspondence between the types of Event message and
             the bits of the Event Flags field is as follows:

                Port Up:          Bit 0, (most significant bit)
                Port Down:        Bit 1,
                Invalid VPI/VCI:  Bit 2,
                New Port:         Bit 3,
                Dead Port:        Bit 4.

   Duration
             Is the length of time, in seconds, that any of the loopback
             states remain in operation. When the duration has expired
             the port will automatically be returned to service.  If
             another Port Management message is received for the same
             port before the duration has expired, the loopback will
             continue to remain in operation for the length of time
             specified by the Duration field in the new message. The
             Duration field is only used in request messages with the
             Function field set to Internal Loopback, External Loopback,
             or Bothway Loopback. In all other request messages it
             should be set to zero by the sender and ignored by the
             receiver.



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RFC 1987              GSMP Protocol Specification            August 1996


   Function
             Specifies the action to be taken. The specified action will
             be taken regardless of the current status of the port
             (Available, Unavailable, or any Loopback state). The
             defined values of the Function field are:

             Bring Up:
                  Function = 1. Bring the port into service. All
                  connections that arrive at the specified input port
                  must be deleted and a new Port Session Number must be
                  selected using some form of random number. On
                  completion of the operation all dynamically assigned
                  VPI/VCI values for the specified input port must be
                  unassigned, i.e. no virtual connections will be
                  established in the VPI/VCI space that GSMP controls on
                  this input port. The Port Status of the port
                  afterwards will be Available.

             Take Down:
                  Function = 2. Take the port out of service. Any cells
                  received at this port will be discarded. No cells will
                  be transmitted from this port. The Port Status of the
                  port afterwards will be Unavailable. The behavior is
                  undefined if the port over which the GSMP protocol is
                  running is taken down.

             Internal Loopback:
                  Function = 3. Cells arriving at the output port from
                  the switch fabric are looped through to the input port
                  to return to the switch fabric. All of the ATM
                  functions of the input port above the PHY layer, e.g.
                  header translation, are performed upon the looped back
                  cells. The Port Status of the port afterwards will be
                  Internal Loopback.

             External Loopback:
                  Function = 4. Cells arriving at the input port from
                  the external communications link are immediately
                  looped back to the communications link at the physical
                  layer without entering the input port. None of the ATM
                  functions of the input port above the PHY layer are
                  performed upon the looped back cells. The Port Status
                  of the port afterwards will be External Loopback.

             Bothway Loopback:
                  Function = 5. Both internal and external loopback are
                  performed. The Port Status of the port afterwards will
                  be Bothway Loopback.



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RFC 1987              GSMP Protocol Specification            August 1996


             Reset Input Port:
                  Function = 6. All connections that arrive at the
                  specified input port must be deleted and the input and
                  output port hardware re-initialized. On completion of
                  the operation all dynamically assigned VPI/VCI values
                  for the specified input port must be unassigned, i.e.
                  no virtual connections will be established in the
                  VPI/VCI space that GSMP controls on this input port.
                  The Port Session Number is not changed by the Reset
                  Input Port function.  The Port Status of the port
                  afterwards will be Unavailable.

             Reset Event Flags:
                  Function = 7. For each bit that is set in the Event
                  Flags field, the corresponding Event Flag in the
                  switch port must be reset. The Port Status of the port
                  is not changed by this function.


5. Statistics Messages

   The statistics messages permit the controller to request the values
   of various hardware counters associated with the switch input and
   output ports, and virtual channels. Two classes of statistics message
   are defined: the VC Activity Message, and the Port and VC Statistics
   Messages. The VC Activity message is used to determine whether one or
   more specific VCs have recently been carrying traffic.  The Port and
   VC Statistics message is used to query the various port and VC
   specific traffic and error counters.

5.1 VC Activity Message

   The VC Activity message is used to determine whether one or more
   specific VCs have recently been carrying traffic. The VC Activity
   message contains one or more VC Activity records. Each VC Activity
   record is used to request and return activity information concerning
   a single virtual connection. Each VC is specified by its input port,
   input VPI, and input VCI. These are specified in the Input Port,
   Input VPI, and Input VCI fields of each VC Activity record.  Two
   forms of activity detection are supported. If the switch supports per
   VC traffic accounting the current value of the traffic counter for
   each specified VC must be returned. The units of traffic counted are
   not specified but will typically be either cells or frames.  The
   controller must compare the traffic counts returned in the message
   with previous values for each of the specified VCs to determine
   whether each VC has been active in the intervening period.  If the
   switch does not support per VC traffic accounting, but is capable of
   detecting per-VC activity by some other unspecified means, the result