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RFC 3292

 
 
 

General Switch Management Protocol (GSMP) V3

Part 3 of 5, p. 47 to 73
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6.  Management Messages

6.1  Port Management Message

   The Port Management message allows a port to be brought into service,
   to be taken out of service, to be set to loop back, reset, or to
   change the transmit data rate.  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.  The Port Management message MAY also be
   used for enabling the replace connection mechanism.  The Port
   Management message is also used as part of the Event Message flow
   control mechanism.

   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

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

    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      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Partition ID  |            Transaction Identifier             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |I|      SubMessage Number      |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                             Port                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Port Session Number                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Event Sequence Number                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |R|x|x|x|x|x|x|x|   Duration    |          Function             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Event Flags         |        Flow Control Flags     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Transmit Data Rate                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Note: Fields and Parameters that have been explained in the
         description of the general messages will not be explained in
         this section.  Please refer to section 3.1 for details.

      Event Sequence Number
         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 initialised.  It is incremented by one each time the port
         detects an asynchronous event 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.

      R: Connection Replace
         The R flag shall only be checked when the Function field = 1
         (Bring Up).  If the R flag is set in the Port Management
         request message, it indicates that a switch controller requests
         the switch port to support the Connection Replace mechanism.

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         Connection Replace behaviour is described in chapter 4.2.  If a
         switch does not support the Connection Replace mechanism, it
         MUST reply with the failure response:  "45: Connection Replace
         mechanism not supported on switch" and reset the R-flag.  Upon
         successful response, the R flag SHOULD remain set in the
         response message.

      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.

      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).  If the specified function
         requires a new Port Session Number to be generated, the new
         Port Session Number MUST be returned in the success response
         message.  The defined values of the Function field are:

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

         Take Down:
            Function = 2.  Take the port out of service.  Any data
            received at this port will be discarded.  No data will be
            transmitted from this port.  Afterwards, the Port Status of
            the port will be Unavailable.

            The behaviour is undefined if the port is taken down over
            which the GSMP session that controls the switch is running.
            (In this case the most probable behaviour would be for the
            switch either to ignore the message or to terminate the
            current GSMP session and to initiate another session,

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            possibly with the backup controller, if any.)  The correct
            method to reset the link over which GSMP is running is to
            issue an RSTACK message in the adjacency protocol.

         Internal Loopback:
            Function = 3.  Data 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 functions of the input
            port above the physical layer, e.g., header translation, are
            performed upon the looped back data.  Afterwards, the Port
            Status of the port will be Internal Loopback.

         External Loopback:
            Function = 4.  Data 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 functions of the input
            port, above the physical layer are performed upon the looped
            back data.  Afterwards, the Port Status of the port will be
            External Loopback.

         Bothway Loopback:
            Function = 5.  Both internal and external loopbacks are
            performed.  Afterwards, the Port Status of the port will be
            Bothway Loopback.

         Reset Input Port:
            Function = 6.  All connections that originate at the
            specified input port MUST be deleted and the input and
            output port hardware re-initialised.  On completion of the
            operation, all dynamically assigned Label values for the
            specified input port MUST be unassigned, i.e., no
            connections will be established in the Label space that GSMP
            controls on this input port.  The range of labels that may
            be controlled by GSMP on this port will be set to the
            default values specified in the Port Configuration message.
            The transmit data rate of the output port MUST be set to its
            default value.  The Port Session Number is not changed by
            the Reset Input Port function.  Afterwards, the Port Status
            of the port will be Unavailable.

         Reset Flags:
            Function = 7.  This function is used to reset the Event
            Flags and Flow Control Flags.  For each bit that is set in
            the Event Flags field, the corresponding Event Flag in the
            switch port MUST be reset to 0.  For each bit that is set in
            the Flow Control Flags field, the corresponding Flow Control
            Flag in the switch port MUST be toggled; i.e., flow control

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            for the corresponding event is turned off if is currently on
            and it is turned on if it is currently off.  The Port Status
            of the port is not changed by this function.

         Set Transmit Data Rate:
            Function = 8.  Sets the transmit data rate of the output
            port as close as possible to the rate specified in the
            Transmit Data Rate field.  In the success response message,
            the Transmit Data Rate MUST indicate the actual transmit
            data rate of the output port.  If the transmit data rate of
            the requested output port cannot be changed a failure
            response MUST be returned with the Code field indicating:
            "43: The transmit data rate of this output port cannot be
            changed".  If the transmit data rate of the requested output
            port can be changed, but the value of the Transmit Data Rate
            field is beyond the range of acceptable values, a failure
            response MUST be returned with the Code field indicating:
            "44: Requested transmit data rate out of range for this
            output port".  In the failure response message, the Transmit
            Data Rate MUST contain the same value as contained in the
            request message that caused the failure.  The transmit data
            rate of the output port is not changed by the Bring Up, Take
            Down, or any of the Loopback functions.  It is returned to
            the default value by the Reset Input Port function.

      Transmit Data Rate
         This field is only used in request and success response
         messages with the Function field set to "Set Transmit Data
         Rate".  It is used to set the output data rate of the output
         port.  It is specified in cells/s and bytes/s.  If the Transmit
         Data Rate field contains the value 0xFFFFFFFF the transmit data
         rate of the output port SHOULD be set to the highest valid
         value.

      Event Flags
         Field in the request message that 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.  Depending on the
         setting in the Flow Control Flag, a port is either subject to
         flow control or not.  If it is subject to flow control, then it
         is not permitted to send another Event message of the same type
         before the Event Flag has been reset.  To reset an event flag,
         the Function field in the request message is set to "Reset
         Flags".  For each bit that is set in the Event Flags field, the
         corresponding Event Flag in the switch port is reset.

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         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 is not
         used.  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 messages and the
         bits of the Event Flags field is as follows:

                                    1
                0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
               |U|D|I|N|Z|A|x|x|x|x|x|x|x|x|x|x|
               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               U: Port Up          Bit  0, (most significant bit)
               D: Port Down        Bit  1,
               I: Invalid Label    Bit  2,
               N: New Port         Bit  3,
               Z: Dead Port        Bit  4,
               A: Adjacency Event  Bit  5,
               x: Unused           Bits 6-15.

      Flow Control Flags Field
         The flags in this field are used to indicate whether the flow
         control mechanism described in the Events Flag field is turned
         on or not.  If the Flow Control Flag is set, then the flow
         control mechanism for that event on that port is activated.  To
         toggle the flow control mechanism, the Function field in the
         request message is set to "Reset Flags".  When doing a reset,
         for each flag that is set in the Flow Control Flags field, the
         corresponding flow control mechanism MUST be toggled.

         The Flow Control Flags correspond to the same event definitions
         as defined for the Event Flag.

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6.2  Label Range Message

   The default label range, Min Label to Max Label, is specified for
   each port by the Port Configuration or the All Ports Configuration
   messages.  When the protocol is initialised, before the transmission
   of any Label Range messages, the label range of each port will be set
   to the default label range.  (The default label range is dependent
   upon the switch design and configuration and is not specified by the
   GSMP protocol.)  The Label Range message allows the range of labels
   supported by a specified port, to be changed.  Each switch port MUST
   declare whether it supports the Label Range message in the Port
   Configuration or the All Ports Configuration messages.  The Label
   Range message is:

      Message Type = 33

   The Label Range message has the following format for the request and
   success response messages:

    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      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Partition ID  |            Transaction Identifier             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |I|      SubMessage Number      |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                             Port                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Port Session Number                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Q|M|D|x|      Range Count      |          Range Length         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                       Label Range Block                       ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Note: Fields and Parameters that have been explained in the
         description of the general messages will not be explained in
         this section.  Please refer to section 3.1 for details.

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   Each element of the Label Range Block has the following format:

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|x|V|C|                                                       |
   +-+-+-+-+                   Min Label                           |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|x|x|x|                                                       |
   +-+-+-+-+                   Max Label                           |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Remaining Labels                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Flags

         Q: Query
            If the Query flag is set in a request message, the switch
            MUST respond with the current range of valid labels.  The
            current label range is not changed by a request message with
            the Query flag set.  If the Query flag is zero, the message
            is requesting a label change operation.

         M: Multipoint Query
            If the Multipoint Query flag is set the switch MUST respond
            with the current range of valid specialized multipoint
            labels.  The current label range is not changed by a request
            message with the Multipoint Query flag set.

         D: Non-contiguous Label Range Indicator
            This flag will be set in a Query response if the labels
            available for assignment belong to a non-contiguous set.

         V: Label
            The Label flag use is port type specific.

         C: Multipoint Capable
            Indicates label range that can be used for multipoint
            connections.

      Range Count
         Count of Label Range elements contained in the Label Range
         Block.

      Range Length
         Byte count in the Label Range Block.

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      Min Label
         The minimum label value in the range.

      Max Label
         The maximum label value in the range.

      Remaining Labels
         The maximum number of remaining labels that could be requested
         for allocation on the specified port.

   The success response to a Label Range message requesting a change of
   label range is a copy of the request message with the Remaining
   Labels field updated to the new values after the Label Range
   operation.

   If the switch is unable to satisfy a request to change the Label
   range, it MUST return a failure response message with the Code field
   set to: "40: Cannot support one or more requested label ranges".  In
   this failure response message, the switch MUST use the Min Label and
   Max Label fields to suggest a label range that it is able to satisfy.

   A Label Range request message may be issued regardless of the Port
   Status or the Line Status of the target switch port.  If the Port
   field of the request message contains an invalid port (a port that
   does not exist or a port that has been removed from the switch) a
   failure response message MUST be returned with the Code field set to,
   "4: One or more of the specified ports does not exist".

   If the Query flag is set in the request message, the switch MUST
   reply with a success response message containing the current range of
   valid labels that are supported by the port.  The Min Label and Max
   Label fields are not used in the request message.

   If the Multipoint Query flag is set in the request message and the
   switch does not support a range of valid multipoint labels, then the
   switch MUST reply with a failure response message with the Code field
   set to, "42: Specialised multipoint labels not supported".  The Min
   Label and Max Label fields are not used in the Multipoint request
   message.

   If a label range changes and there are extant connection states with
   labels used by the previous label range, a success response message
   MUST be returned with the Code field set to, "46: One or more labels
   are still used in the previous Label Range".  This action indicates
   that the label range has successfully changed but with a warning that
   there are extant connection states for the previous label range.

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6.2.1  Labels

6.2.1.1  ATM Labels

   If the Label Type = ATM Label, the labels range message MUST be
   interpreted as an ATM Label as shown:

   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|x|V|C|   ATM Label (0x100)   |          Label Length         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|x|x|x|        min VPI        |            min VCI            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|x|x|x|   ATM Label (0x100)   |          Label Length         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|x|x|x|        max VPI        |            max VCI            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Remaining VPI's         |        Remaining VCI's        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      V: Label
         If the Label flag is set, the message refers to a range of
         VPI's only.  The Min VCI and Max VCI fields are unused.  If the
         Label flag is zero the message refers to a range of VCI's on
         either one VPI or on a range of VPI's.

      Min VPI, Max VPI
         Specify a range of VPI values, Min VPI to Max VPI inclusive.  A
         single VPI may be specified with a Min VPI and a Max VPI having
         the same value.  In a request message, if the value of the Max
         VPI field is less than or equal to the value of the Min VPI
         field, the requested range is a single VPI with a value equal
         to the Min VPI field.  Zero is a valid value.  In a request
         message, if the Query flag is set, and the Label flag is zero,
         the Max VPI field specifies a single VPI and the Min VPI field
         is not used.  The maximum valid value of these fields for both
         request and response messages is 0xFFF.

      Min VCI, Max VCI
         Specify a range of VCI values, Min VCI to Max VCI inclusive.  A
         single VCI may be specified with a Min VCI and a Max VCI having
         the same value.  In a request message, if the value of the Max
         VCI field is less than or equal to the value of the Min VCI
         field, the requested range is a single VCI with a value equal
         to the Min VCI field.  Zero is a valid value.  (However, VPI=0,
         VCI=0 is not available as a virtual channel connection as it is
         used as a special value in ATM to indicate an unassigned cell.)

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      Remaining VPI's, Remaining VCI's
         These fields are unused in the request message.  In the success
         response message and in the failure response message these
         fields give the maximum number of remaining VPI's and VCI's
         that could be requested for allocation on the specified port
         (after completion of the requested operation in the case of the
         success response).  It gives the switch controller an idea of
         how many VPI's and VCI's it could request.  The number given is
         the maximum possible given the constraints of the switch
         hardware.  There is no implication that this number of VPI's
         and VCI's is available to every switch port.

   If the Query flag and the Label flag are set in the request message,
   the switch MUST reply with a success response message containing the
   current range of valid VPI's that are supported by the port.  The Min
   VPI and Max VPI fields are not used in the request message.

   If the Query flag is set and the Label flag is zero in the request
   message, the switch MUST reply with a success response message
   containing the current range of valid VCI's that are supported by the
   VPI specified by the Max VPI field.  If the requested VPI is invalid,
   a failure response MUST be returned indicating: "13: One or more of
   the specified Input Labels is invalid".  The Min VPI field is not
   used in either the request or success response messages.

   If the Query flag is zero and the Label flag is set in the request
   message, the Min VPI and Max VPI fields specify the new range of
   VPI's to be allocated to the input port specified by the Port field.
   The range of VPI's previously allocated to this port SHOULD be
   increased or decreased to the specified value.

   If the Query flag and the Label flag are zero in the request message,
   the Min VCI and Max VCI fields specify the range of VCI's to be
   allocated to each of the VPI's specified by the VPI range.  The range
   of VCI's previously allocated to each of the VPI's within the
   specified VPI range on this port, it SHOULD be increased or decreased
   to the specified value.  The allocated VCI range MUST be the same on
   each of the VPI's within the specified VPI range.

   If the switch is unable to satisfy a request to change the label
   range, it MUST return a failure response message with the Code field
   set to: "40: Cannot support one or more requested label ranges".  If
   the switch is unable to satisfy a request to change the VPI, the
   switch MUST use the Min VPI and Max VPI fields to suggest a VPI range
   that it would be able to satisfy and set the VCI fields to zero, or
   if the switch is unable to satisfy a request to change the VCI range

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   on all VPI's within the requested VPI range, the switch MUST use the
   Min VPI, Max VPI, Min VCI, and Max VCI fields to suggest a VPI and
   VCI range that it would be able to satisfy.

   In all other failure response messages for the label range operation,
   the switch MUST return the values of Min VPI, Max VPI, Min VCI, and
   Max VCI from the request message.

   While switches can typically support all 256 or 4096 VPI's, the VCI
   range that can be supported is often more constrained.  Often the Min
   VCI MUST be 0 or 32.  Typically all VCI's within a particular VPI
   MUST be contiguous.  The hint in the failure response message allows
   the switch to suggest a label range that it could satisfy in view of
   its particular architecture.

   While the Label Range message is defined to specify both a range of
   VPI's and a range of VCI's within each VPI, the most likely use is to
   change either the VPI range or the range of VCI's within a single
   VPI.  It is possible for a VPI to be valid but to be allocated no
   valid VCI's.  Such a VPI could be used for a virtual path connection,
   but to support virtual channel connections it would need to be
   allocated a range of VCI's.

6.2.1.2  Frame Relay Labels

   If the Label Type = FR Label, the labels range message MUST be
   interpreted as Frame Relay Labels as shown:

   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|x|V|C|    FR Label (0x101)   |          Label Length         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|x|x|x| Res |Len|                Min DLCI                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|x|x|x|    FR Label (0x101)   |          Label Length         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|x|x|x| Res |Len|                Max DLCI                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Remaining DLCI                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      V: Label
         The Label flag is not used.

      Res
         The Res field is reserved in [21], i.e., it is not explicitly
         reserved by GSMP.

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      Len
         The Len field specifies the number of bits of the DLCI.  The
         following values are supported:

         Len  DLCI bits
         0    10
         2    23

      Min DLCI, Max DLCI
         Specify a range of DLCI values, Min DLCI to Max DLCI inclusive.
         The values SHOULD be right justified in the 23-bit fields and
         the preceding bits SHOULD be set to zero.  A single DLCI may be
         specified with a Min DLCI and a Max DLCI having the same value.
         In a request message, if the value of the Max DLCI field is
         less than or equal to the value of the Min DLCI field, the
         requested range is a single DLCI with a value equal to the Min
         DLCI field.  Zero is a valid value.

      Remaining DLCI's
         This field is unused in the request message.  In the success
         response message and in the failure response message, this
         field gives the maximum number of remaining DLCI's that could
         be requested for allocation on the specified port (after
         completion of the requested operation in the case of the
         success response).  It gives the switch controller an idea of
         how many DLCI's it could request.  The number given is the
         maximum possible given the constraints of the switch hardware.
         There is no implication that this number of DLCI's is available
         to every switch port.

6.2.1.3  MPLS Generic Labels

   The Label Range Block for PortTypes using MPLS labels.  These types
   of labels are for use on links for which label values are independent
   of the underlying link technology.  Examples of such links are PPP
   and Ethernet.  On such links the labels are carried in MPLS label
   stacks [14].  If Label Type = MPLS Gen Label, the labels range
   message MUST be interpreted as MPLS Generic Label as shown:

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   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|x|V|C| MPLS Gen Label (0x102)|          Label Length         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|x|x|x|x|x|x|x|x|x|x|x|          Min MPLS Label               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|x|x|x| MPLS Gen Label (0x102)|          Label Length         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|x|x|x|x|x|x|x|x|x|x|x|          Max MPLS Label               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Remaining Labels                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      V: Label
         The Label flag is not used.

      Min MPLS Label, Max MPLS Label
         Specify a range of MPLS label values, Min MPLS Label to Max
         MPLS Label inclusive.  The Max and Min MPLS label fields are 20
         bits each.

      Remaining MPLS Labels
         This field is unused in the request message.  In the success
         response message and in the failure response message this field
         gives the maximum number of remaining MPLS Labels that could be
         requested for allocation on the specified port (after
         completion of the requested operation in the case of the
         success response).  It gives the switch controller an idea of
         how many MPLS Labels it could request.  The number given is the
         maximum possible given the constraints of the switch hardware.
         There is no implication that this number of Labels is available
         to every switch port.

6.2.1.4  FEC Labels

   The Label Range message is not used for FEC Labels and is for further
   study.

7.  State and Statistics Messages

   The state and statistics messages permit the controller to request
   the values of various hardware counters associated with the switch
   input and output ports and connections.  They also permit the
   controller to request the connection state of a switch input port.
   The Connection Activity message is used to determine whether one or

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   more specific connections have recently been carrying traffic.  The
   Statistics message is used to query the various port and connection
   traffic and error counters.

   The Report Connection State message is used to request an input port
   to report the connection state for a single connection, a single ATM
   virtual path connection, or for the entire input port.

7.1  Connection Activity Message

   The Connection Activity message is used to determine whether one or
   more specific connections have recently been carrying traffic.  The
   Connection Activity message contains one or more Activity Records.
   Each Activity Record is used to request and return activity
   information concerning a single connection.  Each connection is
   specified by its input port and Input Label which are specified in
   the Input Port and Input Label fields of each Activity Record.

   Two forms of activity detection are supported.  If the switch
   supports per connection traffic accounting, the current value of the
   traffic counter for each specified connection 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 connections to determine whether each connection has been
   active in the intervening period.  If the switch does not support per
   connection traffic accounting, but is capable of detecting per
   connection activity by some other unspecified means, the result may
   be indicated for each connection using the Flags field.  The
   Connection Activity message is:

      Message Type = 48

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   The Connection Activity request and success response messages have
   the following format:

    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      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Partition ID  |            Transaction Identifier             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |I|      SubMessage Number      |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Number of Records       |x x x x x x x x x x x x x x x x|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                       Activity Records                        ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Note: Fields and Parameters that have been explained in the
         description of the general messages will not be explained in
         this section.  Please refer to section 3.1 for details.

      Number of Records
         Field specifies the number of Activity Records to follow.  The
         number of Activity records in a single Connection Activity
         message MUST NOT cause the packet length to exceed the maximum
         transmission unit defined by the encapsulation.

   Each Activity Record has the following format:

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |V|C|A|x|          TC Count     |        TC Block Length        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Input Port                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                         Traffic Count                         +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|S|x|x|                                                       |
   +-+-+-+-+                  Input Label                          |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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      Flags

         V: Valid Record
            In the success response message the Valid Record flag is
            used to indicate an invalid Activity Record.  The flag MUST
            be zero if any of the fields in this Activity Record are
            invalid, if the input port specified by the Input Port field
            does not exist, or if the specified connection does not
            exist.  If the Valid Record flag is zero in a success
            response message, the Counter flag, the Activity flag, and
            the Traffic Count field are undefined.  If the Valid Record
            flag is set, the Activity Record is valid, and the Counter
            and Activity flags are valid.  The Valid Record flag is not
            used in the request message.

         C: Counter
            In a success response message, if the Valid Record flag is
            set, the Counter flag, if zero, indicates that the value in
            the Traffic Count field is valid.  If set, it indicates that
            the value in the Activity flag is valid.  The Counter flag
            is not used in the request message.

         A: Activity
            In a success response message, if the Valid Record and
            Counter flags are set, the Activity flag, if set, indicates
            that there has been some activity on this connection since
            the last Connection Activity message for this connection.
            If zero, it indicates that there has been no activity on
            this connection since the last Connection Activity message
            for this connection.  The Activity flag is not used in the
            request message.

      TC Count
         In cases where per connection traffic counting is supported,
         this field contains the count of Traffic Count entries.

      TC Block Length
         In cases where per connection traffic counting is supported,
         this field contains the Traffic Count block size in bytes.

      Input Port
         Identifies the port number of the input port on which the
         connection of interest originates in order to identify the
         connection (regardless of whether the traffic count for the
         connection is maintained on the input port or the output port).

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      Input Label
         Fields identify the specific connection for which statistics
         are being requested.

      Traffic Count
         Field is not used in the request message.  In the success
         response message, if the switch supports per connection traffic
         counting, the Traffic Count field MUST be set to the value of a
         free running, connection specific, 64-bit traffic counter
         counting traffic flowing across the specified connection.  The
         value of the traffic counter is not modified by reading it.  If
         per connection traffic counting is supported, the switch MUST
         report the Connection Activity result using the traffic count
         rather than using the Activity flag.

   The format of the failure response is the same as the request message
   with the Number of Records field set to zero and no Connection
   Activity records returned in the message.  If the switch is incapable
   of detecting per connection activity, a failure response MUST be
   returned indicating, "3: The specified request is not implemented on
   this switch".

7.2  Statistics Messages

   The Statistics messages are used to query the various port,
   connection and error counters.

   The Statistics request messages have the following format:

    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      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Partition ID  |            Transaction Identifier             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |I|      SubMessage Number      |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                             Port                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|S|x|x|                                                       |
   +-+-+-+-+                     Label                             |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Note: Fields and Parameters that have been explained in the
         description of the general messages will not be explained in
         this section.  Please refer to section 3.1 for details.

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      Label
         The Label Fields identifies the specific connection for which
         statistics are being requested.

   The success response for the Statistics message has the following
   format:

    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      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Partition ID  |           Transaction Identifier              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |I|      SubMessage Number      |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                             Port                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|S|x|x|                                                       |
   +-+-+-+-+                     Label                             |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                       Input Cell Count                        +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                       Input Frame Count                       +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                    Input Cell Discard Count                   +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                   Input Frame Discard Count                   +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                  Header Checksum Error Count                  +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                   Input Invalid Label Count                   +
   |                                                               |

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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                       Output Cell Count                       +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                      Output Frame Count                       +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                   Output Cell Discard Count                   +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                  Output Frame Discard Count                   +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Note: Field and Parameters that have been explained in the
         description of the general messages will not be explained in
         this section.  Please refer to section 3.1 for details.

      Input Cell Count, Output Cell Count
         Give the value of a free running 64-bit counter counting cells
         arriving at the input or departing from the output
         respectively.  These fields are relevant for label type = ATM,
         for all other label types these fields SHOULD be set to zero by
         the sender and ignored by the receiver.

      Input Frame Count, Output Frame Count
         Give the value of a free running 64-bit counter counting frames
         (packets) arriving at the input or departing from the output
         respectively.  These fields are relevant for label types = FR
         and MPLS, for all other label types these fields SHOULD be set
         to zero by the sender and ignored by the receiver.

      Input Cell Discard Count, Output Cell Discard Count
         Give the value of a free running 64-bit counter counting cells
         discarded due to queue overflow on an input port or on an
         output port respectively.  These fields are relevant for label
         type = ATM, for all other label types these fields SHOULD be
         set to zero by the sender and ignored by the receiver.

      Input Frame Discard Count, Output Frame Discard Count
         Give the value of a free running 64-bit counter counting frames
         discarded due to congestion on an input port or on an output
         port respectively.  These fields are relevant for label

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         types = FR and MPLS, for all other label types these fields
         SHOULD be set to zero by the sender and ignored by the
         receiver.

      Header Checksum Error Count
         Gives the value of a free running 64-bit counter counting cells
         or frames discarded due to header checksum errors on arrival at
         an input port.  For an ATM switch this would be the HEC count.

      Invalid Label Count
         Gives the value of a free running 64-bit counter counting cells
         or frames discarded because their Label is invalid on arrival
         at an input port.

7.2.1  Port Statistics Message

   The Port Statistics message requests the statistics for the switch
   port specified in the Port field.  The contents of the Label field in
   the Port Statistics request message is ignored.  All of the count
   fields in the success response message refer to per-port counts
   regardless of the connection to which the cells or frames belong.
   Any of the count fields in the success response message not supported
   by the port MUST be set to zero.  The Port Statistics message is:

      Message Type = 49

7.2.2  Connection Statistics Message

   The Connection Statistics message requests the statistics for the
   connection specified in the Label field that originates on the switch
   input port specified in the Port field.  All of the count fields in
   the success response message refer only to the specified connection.
   The Header Checksum Error Count and Invalid Label Count fields are
   not connection specific and MUST be set to zero.  Any of the other
   count fields not supported on a per connection basis MUST be set to
   zero in the success response message.  The Connection Statistics
   message is:

      Message Type = 50

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7.2.3  QoS Class Statistics Message

   The QoS Class Statistics message is not supported in this version of
   GSMP.

      Message Type = 51 is reserved.

7.3  Report Connection State Message

   The Report Connection State message is used to request an input port
   to report the connection state for a single connection or for the
   entire input port.  The Report Connection State message is:

      Message Type = 52

   The Report Connection State request message has the following format:

    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      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Partition ID  |            Transaction Identifier             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |I|      SubMessage Number      |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Input Port                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|S|A|V|                                                       |
   +-+-+-+-+                  Input Label                          |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Note: Field and Parameters that have been explained in the
         description of the general messages will not be explained in
         this section.  Please refer to section 3.1 for details.

      Input Port
         Identifies the port number of the input port for which the
         connection state is being requested.

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      Flags

         A: All Connections
            If the All Connections flag is set, the message requests the
            connection state for all connections that originate at the
            input port specified by the Input Port field.  In this case
            the Input Label field and the Label flag are unused.

         V: ATM VPI
            The ATM VPI flag may only be set for ports with
            PortType=ATM.  If the switch receives a Report Connection
            State message in which the ATM VPI flag set and in which the
            input port specified by the Input Port field does not have
            PortType=ATM, the switch MUST return a Failure response "28:
            ATM Virtual Path switching is not supported on non-ATM
            ports".

            If the All Connections flag is zero and the ATM VPI flag is
            also zero, the message requests the connection state for the
            connection that originates at the input port specified by
            the Port and Input Label fields.

         ATM specific procedures:
            If the All Connections flag is zero and the ATM VPI flag is
            set and the input port specified by the Input Port field has
            LabelType=ATM, the message requests the connection state for
            the virtual path connection that originates at the input
            port specified by the Input Port and Input VPI fields.  If
            the specified Input VPI identifies an ATM virtual path
            connection (i.e., a single switched virtual path) the state
            for that connection is requested.  If the specified Input
            VPI identifies a virtual path containing virtual channel
            connections, the message requests the connection state for
            all virtual channel connections that belong to the specified
            virtual path.

      Input Label
         Field identifies the specific connection for which the
         connection state is being requested.  For requests that do not
         require a connection to be specified, the Input Label field is
         not used.

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   The Report Connection State success response message has the
   following format:

    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      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Partition ID  |            Transaction Identifier             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |I|      SubMessage Number      |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Input Port                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Sequence Number                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                       Connection Records                      ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Note: Fields and Parameters that have been explained in the
         description of the general messages will not be explained in
         this section.  Please refer to section 3.1 for details.

      Input Port
         Is the same as the Input Port field in the request message.  It
         identifies the port number of the input port for which the
         connection state is being reported.

      Sequence Number
         In the case that the requested connection state cannot be
         reported in a single success response message, each successive
         success response message, in reply to the same request message,
         MUST increment the Sequence Number.  The Sequence Number of the
         first success response message, in response to a new request
         message, MUST be zero.

      Connection Records
         Each success response message MUST contain one or more
         Connection Records.  Each Connection Record specifies a single
         point-to-point or point-to-multipoint connection.  The number
         of Connection Records in a single Report Connection State
         success response MUST NOT cause the packet length to exceed the
         maximum transmission unit defined by the encapsulation.  If the
         requested connection state cannot be reported in a single
         success response message, multiple success response messages
         MUST be sent.  All success response messages that are sent in

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         response to the same request message MUST have the same Input
         Port and Transaction Identifier fields as the request message.
         A single Connection Record MUST NOT be split across multiple
         success response messages.  "More" in the Result field of a
         response message indicates that one or more further success
         response messages should be expected in response to the same
         request message.  "Success" in the Result field indicates that
         the response to the request has been completed.  The Result
         values are defined in chapter 3.1.1.

   Each Connection Record has the following format:

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |A|V|P|     Record Count    |           Record Length           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|S|x|x|                                                       |
   +-+-+-+-+                    Input Label                        |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                   Output Branch Records                       ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Flags

         A: All Connections

         V: ATM VPI
            For the first Connection Record in each success response
            message, the All Connections and the ATM VPI flags MUST be
            the same as those of the request message.  For successive
            Connection Records in the same success response message,
            these flags are not used.

         P: ATM VPC
            The ATM VPC flag may only be set for ports with
            PortType=ATM.  The ATM VPC flag, if set and only if set,
            indicates that the Connection Record refers to an ATM
            virtual path connection.

      Input Label
         The input label of the connection specified in this Connection
         Record.

      Record Count
         Count of Output Branch Records included in a response message.

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      Record Length
         Length in bytes of Output Branch Records field

      Output Branch Records
         Each Connection Record MUST contain one or more Output Branch
         Records.  Each Output Branch Record specifies a single output
         branch belonging to the connection identified by the Input
         Label field of the Connection Record and the Input Port field
         of the Report Connection State message.  A point-to-point
         connection will require only a single Output Branch Record.  A
         point-to-multipoint connection will require multiple Output
         Branch Records.  If a point-to-multipoint connection has more
         output branches than can fit in a single Connection Record
         contained within a single success response message, that
         connection may be reported using multiple Connection Records in
         multiple success response messages.

   Each Output Branch Record has the following format:

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Output Port                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|S|x|x|                                                       |
   +-+-+-+-+                    Output Label                       |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Output Port
         The output port of the switch to which this output branch is
         routed.

      Output Label
         The output label of the output branch specified in this Output
         Branch Record.

         ATM specific procedures:
            If this Output Branch Record is part of a Connection Record
            that specifies a virtual path connection (the ATM VPC flag
            is set) the Output VCI field is unused.

   A Report Connection State request message may be issued regardless of
   the Port Status or the Line Status of the target switch port.

   If the Input Port of the request message is valid, and the All
   Connections flag is set, but there are no connections established on
   that port, a failure response message MUST be returned with the Code
   field set to, "10: General Message Failure".  For the Report
   Connection State message, this failure code indicates that no

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   connections matching the request message were found.  This failure
   message SHOULD also be returned if the Input Port of the request
   message is valid, the All Connections flag is zero, and no
   connections are found on that port matching the specified connection.



(page 73 continued on part 4)

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