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RFC 3332

 
 
 

Signaling System 7 (SS7) Message Transfer Part 3 (MTP3) - User Adaptation Layer (M3UA)

Part 2 of 4, p. 25 to 58
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3. M3UA Protocol Elements

   The general M3UA message format includes a Common Message Header
   followed by zero or more parameters as defined by the Message Type.
   For forward compatibility, all Message Types may have attached
   parameters even if none are specified in this version.

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3.1 Common Message Header

   The protocol messages for MTP3-User Adaptation require a message
   header which contains the adaptation layer version, the message type,
   and message length.

      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    |   Reserved    | Message Class | Message Type  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Message Length                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                                                               /

   All fields in an M3UA message MUST be transmitted in the network byte
   order, unless otherwise stated.

3.1.1 M3UA Protocol Version: 8 bits (unsigned integer)

   The version field contains the version of the M3UA adaptation layer.

   The supported versions are the following:

         1      Release 1.0

3.1.2  Message Classes and Types

   The following list contains the valid Message Classes:

   Message Class: 8 bits (unsigned integer)

   The following list contains the valid Message Type Classes:

        0     Management (MGMT) Messages
        1     Transfer Messages
        2     SS7 Signalling Network Management (SSNM) Messages
        3     ASP State Maintenance (ASPSM) Messages
        4     ASP Traffic Maintenance (ASPTM) Messages
        5     Reserved for Other Sigtran Adaptation Layers
        6     Reserved for Other Sigtran Adaptation Layers
        7     Reserved for Other Sigtran Adaptation Layers
        8     Reserved for Other Sigtran Adaptation Layers
        9     Routing Key Management (RKM) Messages
       10 to 127 Reserved by the IETF
      128 to 255 Reserved for IETF-Defined Message Class extensions

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      Message Type: 8 bits (unsigned integer)

      The following list contains the message types for the defined
      messages.

      Management (MGMT) Messages (See Section 3.8)

        0        Error (ERR)
        1        Notify (NTFY)
     2 to 127    Reserved by the IETF
   128 to 255    Reserved for IETF-Defined MGMT extensions

      Transfer Messages (See Section 3.3)

        0        Reserved
        1        Payload Data (DATA)
     2 to 127    Reserved by the IETF
   128 to 255    Reserved for IETF-Defined Transfer extensions

      SS7 Signalling Network Management (SSNM) Messages (See Section
      3.4)

        0        Reserved
        1        Destination Unavailable (DUNA)
        2        Destination Available (DAVA)
        3        Destination State Audit (DAUD)
        4        Signalling Congestion (SCON)
        5        Destination User Part Unavailable (DUPU)
        6        Destination Restricted (DRST)
     7 to 127    Reserved by the IETF
   128 to 255    Reserved for IETF-Defined SSNM extensions

      ASP State Maintenance (ASPSM) Messages (See Section 3.5)

        0        Reserved
        1        ASP Up (ASPUP)
        2        ASP Down (ASPDN)
        3        Heartbeat (BEAT)
        4        ASP Up Acknowledgement (ASPUP ACK)
        5        ASP Down Acknowledgement (ASPDN ACK)
        6        Heartbeat Acknowledgement (BEAT ACK)
     7 to 127    Reserved by the IETF
   128 to 255    Reserved for IETF-Defined ASPSM extensions

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      ASP Traffic Maintenance (ASPTM) Messages (See Section 3.7)

        0        Reserved
        1        ASP Active (ASPAC)
        2        ASP Inactive (ASPIA)
        3        ASP Active Acknowledgement (ASPAC ACK)
        4        ASP Inactive Acknowledgement (ASPIA ACK)
     5 to 127    Reserved by the IETF
   128 to 255    Reserved for IETF-Defined ASPTM extensions

      Routing Key Management (RKM) Messages (See Section 3.6)

        0        Reserved
        1        Registration Request (REG REQ)
        2        Registration Response (REG RSP)
        3        Deregistration Request (DEREG REQ)
        4        Deregistration Response (DEREG RSP)
     5 to 127    Reserved by the IETF
   128 to 255    Reserved for IETF-Defined RKM extensions

3.1.3  Reserved: 8 bits

   The Reserved field SHOULD be set to all '0's and ignored by the
   receiver.

3.1.4  Message Length: 32-bits (unsigned integer)

   The Message Length defines the length of the message in octets,
   including the Common Header.  The Message Length MUST include
   parameter padding bytes, if any.

   Note: A receiver SHOULD accept the message whether or not the final
   parameter padding is included in the message length.

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3.2 Variable Length Parameter Format

   M3UA messages consist of a Common Header followed by zero or more
   variable length parameters, as defined by the message type.  All the
   parameters contained in a message are defined in a Tag Length-Value
   format as shown below.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Parameter Tag        |       Parameter Length        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                       Parameter Value                         /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Where more than one parameter is included in a message, the
   parameters may be in any order, except where explicitly mandated.  A
   receiver SHOULD accept the parameters in any order.

   Parameter Tag: 16 bits (unsigned integer)

      The Tag field is a 16-bit identifier of the type of parameter. It
      takes a value of 0 to 65534.  Common parameters used by adaptation
      layers are in the range of 0x00 to 0x3f.   M3UA-specific
      parameters have Tags in the range 0x0200 to 0x02ff.  The parameter
      Tags defined are as follows:

      Common Parameters.  These TLV parameters are common across the
      different adaptation layers:

        Parameter Name                     Parameter ID
        ==============                     ============
        Reserved                              0x0000
        Not Used in M3UA                      0x0001
        Not Used in M3UA                      0x0002
        Not Used in M3UA                      0x0003
        INFO String                           0x0004
        Not Used in M3UA                      0x0005
        Routing Context                       0x0006
        Diagnostic Information                0x0007
        Not Used in M3UA                      0x0008
        Heartbeat Data                        0x0009
        Not Used in M3UA                      0x000a
        Traffic Mode Type                     0x000b
        Error Code                            0x000c
        Status                                0x000d

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        Not Used in M3UA                      0x000e
        Not Used in M3UA                      0x000f
        Not Used in M3UA                      0x0010
        ASP Identifier                        0x0011
        Affected Point Code                   0x0012
        Correlation ID                        0x0013

      M3UA-Specific parameters.  These TLV parameters are specific to
      the M3UA protocol:

        Network Appearance                    0x0200
        Reserved                              0x0201
        Reserved                              0x0202
        Reserved                              0x0203
        User/Cause                            0x0204
        Congestion Indications                0x0205
        Concerned Destination                 0x0206
        Routing Key                           0x0207
        Registration Result                   0x0208
        Deregistration Result                 0x0209
        Local_Routing Key Identifier          0x020a
        Destination Point Code                0x020b
        Service Indicators                    0x020c
        Reserved                              0x020d
        Originating Point Code List           0x020e
        Circuit Range                         0x020f
        Protocol Data                         0x0210
        Reserved                              0x0211
        Registration Status                   0x0212
        Deregistration Status                 0x0213

        Reserved by the IETF             0x0214 to 0xffff

      The value of 65535 is reserved for IETF-defined extensions.
      Values other than those defined in specific parameter description
      are reserved for use by the IETF.

   Parameter Length: 16 bits (unsigned integer)

      The Parameter Length field contains the size of the parameter in
      bytes, including the Parameter Tag, Parameter Length, and
      Parameter Value fields.  Thus, a parameter with a zero-length
      Parameter Value field would have a Length field of 4.  The
      Parameter Length does not include any padding bytes.

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   Parameter Value: variable length.

      The Parameter Value field contains the actual information to be
      transferred in the parameter.

      The total length of a parameter (including Tag, Parameter Length
      and Value fields) MUST be a multiple of 4 bytes.  If the length of
      the parameter is not a multiple of 4 bytes, the sender pads the
      Parameter at the end (i.e., after the Parameter Value field) with
      all zero bytes.  The length of the padding is NOT included in the
      parameter length field.  A sender SHOULD NOT pad with more than 3
      bytes.  The receiver MUST ignore the padding bytes.

3.3 Transfer Messages

   The following section describes the Transfer messages and parameter
   contents.

3.3.1 Payload Data Message (DATA)

   The DATA message contains the SS7 MTP3-User protocol data, which is
   an MTP-TRANSFER primitive, including the complete MTP3 Routing Label.
   The DATA message contains the following variable length parameters:

      Network Appearance       Optional
      Routing Context          Optional
      Protocol Data            Mandatory
      Correlation Id           Optional

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   The following format MUST be used for the Data Message:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Tag = 0x0200           |          Length = 8           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Network Appearance                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Tag = 0x0006           |          Length = 8           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Routing Context                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Tag = 0x0210           |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                        Protocol Data                          /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Tag = 0x0013           |          Length = 8           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Correlation Id                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Network Appearance: 32-bits (unsigned integer)

      The Network Appearance parameter identifies the SS7 network
      context for the message and implicitly identifies the SS7 Point
      Code format used, the SS7 Network Indicator value, and the MTP3
      and possibly the MTP3-User protocol type/variant/version used
      within the specific SS7 network.  Where an SG operates in the
      context of a single SS7 network, or individual SCTP associations
      are dedicated to each SS7 network context, the Network Appearance
      parameter is not required.  In other cases the parameter may be
      configured to be present for the use of the receiver.

      The Network Appearance parameter value is of local significance
      only, coordinated between the SGP and ASP. Therefore, in the case
      where an ASP is connected to more than one SGP, the same SS7
      network context may be identified by different Network Appearance
      values depending over which SGP a message is being
      transmitted/received.

      Where the optional Network Appearance parameter is present, it
      must be the first parameter in the message as it defines the
      format of the Protocol Data field.

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      IMPLEMENTATION NOTE: For simplicity of configuration it may be
      desirable to use the same NA value across all nodes sharing a
      particular network context.

   Routing Context: 32-bits (unsigned integer)

      The Routing Context parameter contains the Routing Context value
      associated with the DATA message.   Where a Routing Key has not
      been coordinated between the SGP and ASP, sending of Routing
      Context is not required.  Where multiple Routing Keys and Routing
      Contexts are used across a common association, the Routing Context
      MUST be sent to identify the traffic flow, assisting in the
      internal distribution of Data messages.

   Protocol Data: variable length

      The Protocol Data parameter contains the original SS7 MTP3
      message, including the Service Information Octet and Routing
      Label.

      The Protocol Data parameter contains the following fields:

         Service Indicator,
         Network Indicator,
         Message Priority.

         Destination Point Code,
         Originating Point Code,

         Signalling Link Selection Code (SLS).

         User Protocol Data.  Includes:

            MTP3-User protocol elements (e.g., ISUP, SCCP, or TUP
            parameters).

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   The Protocol Data parameter is encoded as follows:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     Originating Point Code                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     Destination Point Code                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       SI      |       NI      |      MP       |      SLS      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                     User Protocol Data                        /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Originating Point Code: 32 bits (unsigned integer)
   Destination Point Code: 32 bits (unsigned integer)

   The Originating and Destination Point Code fields contains the OPC
   and DPC from the routing label of the original SS7 message in Network
   Byte Order, justified to the least significant bit.  Unused bits are
   coded `0'.

   Service Indicator: 8 bits (unsigned integer)

   The Service Indicator field contains the SI field from the original
   SS7 message justified to the least significant bit.  Unused bits are
   coded `0'.

   Network Indicator: 8-bits (unsigned integer)

   The Network Indicator contains the NI field from the original SS7
   message justified to the least significant bit.  Unused bits are
   coded `0'.

   Message Priority: 8 bits (unsigned integer)

   The Message Priority field contains the MP bits (if any) from the
   original SS7 message, both for ANSI-style and TTC-style [29] message
   priority bits. The MP bits are aligned to the least significant bit.
   Unused bits are coded `0'.

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   Signalling Link Selection: 8 bits (unsigned integer)

   The Signalling Link Selection field contains the SLS bits from the
   routing label of the original SS7 message justified to the least
   significant bit and in Network Byte Order.  Unused bits are coded
   `0'.

   User Protocol Data: (byte string)

   The User Protocol Data field contains a byte string of MTP-User
   information from the original SS7 message starting with the first
   byte of the original SS7 message following the Routing Label.

   Correlation Id: 32-bits (unsigned integer)

   The Correlation Id parameter uniquely identifies the MSU carried in
   the Protocol Data within an AS.  This Correlation Id parameter is
   assigned by the sending M3UA.

3.4 SS7 Signalling Network Management (SSNM) Messages

3.4.1 Destination Unavailable (DUNA)

   The DUNA message is sent from an SGP in an SG to all concerned ASPs
   to indicate that the SG has determined that one or more SS7
   destinations are unreachable.  It is also sent by an SGP in response
   to a message from the ASP to an unreachable SS7 destination.  As an
   implementation option the SG may suppress the sending of subsequent
   "response" DUNA messages regarding a certain unreachable SS7
   destination for a certain period to give the remote side time to
   react.  If there is no alternate route via another SG, the MTP3-User
   at the ASP is expected to stop traffic to the affected destination
   via the SG as per the defined MTP3-User procedures.

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   The DUNA message contains the following parameters:

      Network Appearance      Optional
      Routing Context         Optional
      Affected Point Code     Mandatory
      INFO String             Optional

   The format for DUNA Message parameters is as follows:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0200          |          Length = 8           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      Network Appearance                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Tag = 0x0006           |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                       Routing Context                         /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0012          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Mask      |                 Affected PC 1                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                              ...                              /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Mask      |                 Affected PC n                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x0004         |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                          INFO String                          /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Network Appearance: 32-bit unsigned integer

      See Section 3.3.1

   Routing Context: n x 32-bits (unsigned integer)

      The optional Routing Context parameter contains the Routing
      Context values associated with the DUNA message.  Where a Routing
      Key has not been coordinated between the SGP and ASP, sending of

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      Routing Context is not required.  Where multiple Routing Keys and
      Routing Contexts are used across a common association, the Routing
      Context(s) MUST be sent to identify the concerned traffic flows
      for which the DUNA message applies, assisting in outgoing traffic
      management and internal distribution of MTP-PAUSE indications to
      MTP3-Users at the receiver.

   Affected Point Code: n x 32-bits

      The Affected Point Code parameter contains a list of Affected
      Destination Point Code fields, each a three-octet parameter to
      allow for 14-, 16- and 24-bit binary formatted SS7 Point Codes.
      Affected Point Codes that are less than 24-bits, are padded on the
      left to the 24-bit boundary.  The encoding is shown below for ANSI
      and ITU Point Code examples.

   ANSI 24-bit Point Code:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Mask      |    Network    |    Cluster    |     Member    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      |MSB-----------------------------------------LSB|

   ITU 14-bit Point Code:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Mask      |0 0 0 0 0 0 0 0 0 0|Zone |     Region    | SP  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                           |MSB--------------------LSB|

      It is optional to send an Affected Point Code parameter with more
      than one Affected PC but it is mandatory to receive it.  Including
      multiple Affected PCs may be useful when reception of an MTP3
      management message or a linkset event simultaneously affects the
      availability status of a list of destinations at an SG.

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   Mask: 8-bits (unsigned integer)

      The Mask field can be used to identify a contiguous range of
      Affected Destination Point Codes.  Identifying a contiguous range
      of Affected DPCs may be useful when reception of an MTP3
      management message or a linkset event simultaneously affects the
      availability status of a series of destinations at an SG.

      The Mask parameter is an integer representing a bit mask that can
      be applied to the related Affected PC field.  The bit mask
      identifies how many bits of the Affected PC field are significant
      and which are effectively "wildcarded".  For example, a mask of
      "8" indicates that the last eight bits of the PC is "wildcarded".
      For an ANSI 24-bit Affected PC, this is equivalent to signalling
      that all PCs in an ANSI Cluster are unavailable.  A mask of "3"
      indicates that the last three bits of the PC is "wildcarded".  For
      a 14-bit ITU Affected PC, this is equivalent to signaling that an
      ITU

      Region is unavailable.  A mask value equal (or greater than) the
      number of bits in the PC indicates that the entire network
      appearance is affected - this is used to indicate network
      isolation to the ASP.

   INFO String: variable length

      The optional INFO String parameter can carry any meaningful UTF-8
      [10] character string along with the message.  Length of the INFO
      String parameter is from 0 to 255 octets.  No procedures are
      presently identified for its use but the INFO String MAY be used
      for debugging purposes.

3.4.2 Destination Available (DAVA)

   The DAVA message is sent from an SGP to all concerned ASPs to
   indicate that the SG has determined that one or more SS7 destinations
   are now reachable (and not restricted), or in response to a DAUD
   message if appropriate. If the ASP M3UA layer previously had no
   routes to the affected destinations the ASP MTP3-User protocol is
   informed and may now resume traffic to the affected destination.  The
   ASP M3UA layer now routes the MTP3-user traffic through the SG
   initiating the DAVA message.

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   The DAVA message contains the following parameters:

      Network Appearance       Optional
      Routing Context          Optional
      Affected Point Code      Mandatory
      INFO String              Optional

   The format and description of the Network Appearance, Routing
   Context, Affected Point Code and INFO String parameters is the same
   as for the DUNA message (See Section 3.4.1).

3.4.3 Destination State Audit (DAUD)

   The DAUD message MAY be sent from the ASP to the SGP to audit the
   availability/congestion state of SS7 routes from the SG to one or
   more affected destinations.

   The DAUD message contains the following parameters:

      Network Appearance      Optional
      Routing Context         Optional
      Affected Point Code     Mandatory
      INFO String             Optional

   The format and description of DAUD Message parameters is the same as
   for the DUNA message (See Section 3.4.1).

3.4.4 Signalling Congestion (SCON)

   The SCON message can be sent from an SGP to all concerned ASPs to
   indicate that an SG has determined that there is congestion in the
   SS7 network to one or more destinations, or to an ASP in response to
   a DATA or DAUD message as appropriate.  For some MTP protocol
   variants (e.g., ANSI MTP) the SCON message may be sent when the SS7
   congestion level changes.  The SCON message MAY also be sent from the
   M3UA layer of an ASP to an M3UA peer indicating that the M3UA layer
   or the ASP is congested.

   The SCON message contains the following parameters:

      Network Appearance       Optional
      Routing Context          Optional
      Affected Point Code      Mandatory
      Concerned Destination    Optional
      Congestion Indications   Optional
      INFO String              Optional

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   The format for SCON Message parameters is as follows:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0200          |           Length = 8          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Network Appearance                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Tag = 0x0006           |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                       Routing Context                         /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0012          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Mask     |                 Affected PC 1                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                              ...                              /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Mask     |                 Affected PC n                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0206          |             Length = 8        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    reserved   |                 Concerned DPC                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0205          |             Length = 8        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Reserved                    |  Cong. Level  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            Tag = 0x0004       |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                         INFO String                           /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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   The format and description of the Network Appearance, Routing
   Context, Affected Point Code, and INFO String parameters is the same
   as for the DUNA message (See Section 3.4.1).

   The Affected Point Code parameter can be used to indicate congestion
   of multiple destinations or ranges of destinations.

   Concerned Destination: 32-bits

      The optional Concerned Destination parameter is only used if the
      SCON message is sent from an ASP to the SGP. It contains the point
      code of the originator of the message that triggered the SCON
      message. The Concerned Destination parameter contains one
      Concerned Destination Point Code field, a three-octet parameter to
      allow for 14-, 16- and 24-bit binary formatted SS7 Point Codes.  A
      Concerned Point Code that is less than 24-bits is padded on the
      left to the 24-bit boundary.  Any resulting Transfer Controlled
      (TFC) message from the SG is sent to the Concerned Point Code
      using the single Affected DPC contained in the SCON message to
      populate the (affected) Destination field of the TFC message

   Congested Indications: 32-bits

      The optional Congestion Indications parameter contains a
      Congestion Level field.  This optional parameter is used to
      communicate congestion levels in national MTP networks with
      multiple congestion thresholds, such as in ANSI MTP3.  For MTP
      congestion methods without multiple congestion levels (e.g., the
      ITU international method) the parameter is not included.

   Congestion Level field: 8-bits (unsigned integer)

      The Congestion Level field, associated with all of the Affected
      DPC(s) in the Affected Destinations parameter, contains one of the
      following values:

         0     No Congestion or Undefined
         1     Congestion Level 1
         2     Congestion Level 2
         3     Congestion Level 3

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      The congestion levels are defined in the congestion method in the
      appropriate national MTP recommendations [7,8].

3.4.5 Destination User Part Unavailable (DUPU)

   The DUPU message is used by an SGP to inform concerned ASPs that a
   remote peer MTP3-User Part (e.g., ISUP or SCCP) at an SS7 node is
   unavailable.

   The DUPU message contains the following parameters:

      Network Appearance       Optional
      Routing Context          Optional
      Affected Point Code      Mandatory
      User/Cause               Mandatory
      INFO String              Optional

   The format for DUPU message parameters is as follows:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0200          |             Length = 8        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      Network Appearance                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Tag = 0x0006           |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                       Routing Context                         /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0012          |          Length = 8           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   Mask = 0    |                  Affected PC                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0204          |          Length = 8           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Cause             |            User               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0004          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                          INFO String                          /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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   User/Cause: 32-bits

      The Unavailability Cause and MTP3-User Identity fields, associated
      with the Affected PC in the Affected Point Code parameter, are
      encoded as follows:

   Unavailability Cause field: 16-bits (unsigned integer)

      The Unavailability Cause parameter provides the reason for the
      unavailability of the MTP3-User.  The valid values for the
      Unavailability Cause parameter are shown in the following table.
      The values agree with those provided in the SS7 MTP3 User Part
      Unavailable message.  Depending on the MTP3 protocol used in the
      Network Appearance, additional values may be used - the
      specification of the relevant MTP3 protocol variant/version
      recommendation is definitive.

         0         Unknown
         1         Unequipped Remote User
         2         Inaccessible Remote User

   MTP3-User Identity field: 16-bits (unsigned integer)

      The MTP3-User Identity describes the specific MTP3-User that is
      unavailable (e.g., ISUP, SCCP, ...).  Some of the valid values for
      the MTP3-User Identity are shown below.  The values align with
      those provided in the SS7 MTP3 User Part Unavailable message and
      Service Indicator.  Depending on the MTP3 protocol variant/version
      used in the network appearance, additional values may be used.
      The relevant MTP3 protocol variant/version recommendation is
      definitive.

          0 to 2   Reserved
             3     SCCP
             4     TUP
             5     ISUP
          6 to 8  Reserved
             9     Broadband ISUP
            10     Satellite ISUP
            11     Reserved
            12     AAL type 2 Signalling
            13     Bearer Independent Call Control (BICC)
            14     Gateway Control Protocol
            15     Reserved

      The format and description of the Affected Point Code parameter is
      the same as for the DUNA message (See Section 3.4.1.) except that
      the Mask field is not used and only a single Affected DPC is

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      included.  Ranges and lists of Affected DPCs cannot be signaled in
      a DUPU message, but this is consistent with UPU operation in the
      SS7 network.  The Affected Destinations parameter in an MTP3 User
      Part Unavailable message (UPU) received by an SGP from the SS7
      network contains only one destination.

      The format and description of the Network Appearance, Routing
      Context, and INFO String parameters is the same as for the DUNA
      message (See Section 3.4.1).

3.4.6 Destination Restricted (DRST)

   The DRST message is optionally sent from the SGP to all concerned
   ASPs to indicate that the SG has determined that one or more SS7
   destinations are now restricted from the point of view of the SG, or
   in response to a DAUD message if appropriate.  The M3UA layer at the
   ASP is expected to send traffic to the affected destination via an
   alternate SG with route(s) of equal priority, but only if such an
   alternate route exists and is available.  If the affected destination
   is currently considered unavailable by the ASP, The MTP3-User should
   be informed that traffic to the affected destination can be resumed.
   In this case, the M3UA layer should route the traffic through the SG
   initiating the DRST message.

   This message is optional for the SG to send and it is optional for
   the ASP to act on any information received in the message.  It is for
   use in the "STP" case described in Section 1.4.1.

   The DRST message contains the following parameters:

      Network Appearance       Optional
      Routing Context          Optional
      Affected Point Code      Mandatory
      INFO String              Optional

   The format and description of the Network Appearance, Routing
   Context, Affected Point Code and INFO String parameters is the same
   as for the DUNA message (See Section 3.4.1).

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3.5 ASP State Maintenance (ASPSM) Messages

3.5.1 ASP Up

   The ASP Up message is used to indicate to a remote M3UA peer that the
   adaptation layer is ready to receive any ASPSM/ASPTM messages for all
   Routing Keys that the ASP is configured to serve.

   The ASP Up message contains the following parameters:

      ASP Identifier                Optional
      INFO String                   Optional

   The format for ASP Up message parameters is as follows:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0011          |           Length = 8          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         ASP Identifier                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0004          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                          INFO String                          /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   ASP Identifier: 32-bit unsigned integer

      The optional ASP Identifier parameter contains a unique value that
      is locally significant among the ASPs that support an AS.  The SGP
      should save the ASP Identifier to be used, if necessary, with the
      Notify message (see Section 3.8.2).

      The format and description of the optional INFO String parameter
      is the same as for the DUNA message (See Section 3.4.1).

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3.5.2 ASP Up Acknowledgement (ASP Up Ack)

   The ASP UP Ack message is used to acknowledge an ASP Up message
   received from a  remote M3UA peer.

   The ASP Up Ack message contains the following parameters:

   INFO String (optional)

   The format for ASP Up Ack message parameters is as follows:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag =0x0004             |             Length          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                          INFO String                          /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The format and description of the optional INFO String parameter is
   the same as for the DUNA message (See Section 3.4.1).  The INFO
   String in an ASP Up Ack message is independent from the INFO String
   in the ASP Up message (i.e., it does not have to echo back the INFO
   String received).

3.5.3 ASP Down

   The ASP Down message is used to indicate to a remote M3UA peer that
   the adaptation layer is NOT ready to receive DATA, SSNM, RKM or ASPTM
   messages.

   The ASP Down message contains the following parameters:

   INFO String    Optional

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   The format for the ASP Down message parameters is as follows:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag =0x0004           |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                         INFO String                           /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The format and description of the optional INFO String parameter is
   the same as for the DUNA message (See Section 3.4.1).

3.5.4 ASP Down Acknowledgement (ASP Down Ack)

   The ASP Down Ack message is used to acknowledge an ASP Down message
   received from a remote M3UA peer.

   The ASP Down Ack message contains the following parameters:

   INFO String     Optional

   The format for the ASP Down Ack message parameters is as follows:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0004          |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                         INFO String                           /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The format and description of the optional INFO String parameter is
   the same as for the DUNA message (See Section 3.4.1).

   The INFO String in an ASP Down Ack message is independent from the
   INFO String in the ASP Down message (i.e., it does not have to echo
   back the INFO String received).

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3.5.5 Heartbeat (BEAT)

   The BEAT message is optionally used to ensure that the M3UA peers are
   still available to each other.  It is recommended for use when the
   M3UA runs over a transport layer other than the SCTP, which has its
   own heartbeat.

   The BEAT message contains the following parameters:

   Heartbeat Data         Optional

   The format for the BEAT message is as follows:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0009          |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                       Heartbeat Data                          /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The Heartbeat Data parameter contents are defined by the sending
   node. The Heartbeat Data could include, for example, a Heartbeat
   Sequence Number and/or Timestamp.  The receiver of a BEAT message
   does not process this field as it is only of significance to the
   sender.  The receiver MUST respond with a BEAT Ack message.

3.5.6 Heartbeat Acknowledgement (BEAT Ack)

   The BEAT Ack message is sent in response to a received BEAT message.
   It includes all the parameters of the received BEAT message, without
   any change.

3.6 Routing Key Management (RKM) Messages [Optional]

3.6.1 Registration Request (REG REQ)

   The REG REQ message is sent by an ASP to indicate to a remote M3UA
   peer that it wishes to register one or more given Routing Keys with
   the remote peer.  Typically, an ASP would send this message to an
   SGP, and expects to receive a REG RSP message in return with an
   associated Routing Context value.

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   The REG REQ message contains the following parameters:

   Routing Key           Mandatory

   One or more Routing Key parameters MAY be included.  The format for
   the REG REQ message is as follows:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x0207         |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                         Routing Key 1                         /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                              ...                              /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x0207         |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                         Routing Key n                         /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Routing Key: variable length

      The Routing Key parameter is mandatory. The sender of this message
      expects that the receiver of this message will create a Routing
      Key entry and assign a unique Routing Context value to it, if the
      Routing Key entry does not already exist.

      The Routing Key parameter may be present multiple times in the
      same message. This is used to allow the registration of multiple
      Routing Keys in a single message.

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   The format of the Routing Key parameter is as follows.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Local-RK-Identifier                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Traffic Mode Type (optional)                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     Destination Point Code                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Network Appearance (optional)                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Service Indicators (optional)                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |              Originating Point Code List (optional)           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Circuit Range List (optional)               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                              ...                              /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     Destination Point Code                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Service Indicators (optional)                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |              Originating Point Code List (optional)           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Circuit Range List (optional)               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Note: The Destination Point Code, Service Indicators, Originating
      Point Code List and Circuit Range List parameters MAY be repeated
      as a grouping within the Routing Key parameter, in the structure
      shown above.

   Local-RK-Identifier: 32-bit unsigned integer

      The mandatory Local-RK-Identifier field is used to uniquely
      identify the registration request.  The Identifier value is
      assigned by the ASP, and is used to correlate the response in an
      REG RSP message with the original registration request.  The
      Identifier value must remain unique until the REG RSP message is
      received.

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   The format of the Local-RK-Identifier field is as follows:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x020a          |         Length = 8            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Local-RK-Identifier value                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Traffic Mode Type: 32-bit (unsigned integer)

   The optional Traffic Mode Type parameter identifies the traffic mode
   of operation of the ASP(s) within an Application Server.  The format
   of the Traffic Mode Type Identifier is as follows:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x000b          |         Length = 8            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Traffic Mode Type                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The valid values for Traffic Mode Type are shown in the following
   table:

         1     Override
         2     Loadshare
         3     Broadcast

   Destination Point Code:

      The Destination Point Code parameter is mandatory, and identifies
      the Destination Point Code of incoming SS7 traffic for which the
      ASP is registering.  The format is the same as described for the
      Affected Destination parameter in the DUNA message (See Section
      3.4.1).  Its format is:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x020b          |         Length = 8            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    Mask = 0   |            Destination Point Code             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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   Network Appearance:

      The optional Network Appearance parameter field identifies the SS7
      network context for the Routing Key, and has the same format as in
      the DATA message (See Section 3.3.1).  The absence of the Network
      Appearance parameter in the Routing Key indicates the use of any
      Network Appearance value.  Its format is:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0200          |         Length = 8            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     Network Appearance                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Service Indicators (SI): n X 8-bit integers

      The optional SI [7,8] field contains one or more Service
      Indicators from the values as described in the MTP3-User Identity
      field of the DUPU message.  The absence of the SI parameter in the
      Routing Key indicates the use of any SI value, excluding of course
      MTP management.  Where an SI parameter does not contain a multiple
      of four SIs, the parameter is padded out to 32-byte alignment.

      The SI format is:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x020c          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      SI #1    |     SI #2     |    SI #3      |    SI #4      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                              ...                              /
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      SI #n    |             0 Padding, if necessary           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   OPC List:

      The Originating Point Code List parameter contains one or more SS7
      OPC entries, and its format is the same as the Destination Point
      Code parameter.  The absence of the OPC List parameter in the
      Routing Key indicates the use of any OPC value,

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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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x020e          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    Mask = 0   |          Origination Point Code #1            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    Mask = 0   |          Origination Point Code #2            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                              ...                              /
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    Mask = 0   |          Origination Point Code #n            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Circuit Range:

      An ISUP controlled circuit is uniquely identified by the SS7 OPC,
      DPC and CIC value.  For the purposes of identifying Circuit Ranges
      in an M3UA Routing Key, the optional Circuit Range parameter
      includes one or more circuit ranges, each identified by an OPC and
      Upper/Lower CIC value.  The DPC is implicit as it is mandatory and
      already included in the DPC parameter of the Routing Key.  The
      absence of the Circuit Range parameter in the Routing Key
      indicates the use of any Circuit Range values, in the case of
      ISUP/TUP traffic.  The Origination Point Code is encoded the same
      as the Destination Point Code parameter, while the CIC values are
      16-bit integers.

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   The Circuit Range format is as follows:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Tag = 0x020f        |              Length           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    Mask = 0   |          Origination Point Code #1            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Lower CIC Value #1      |      Upper CIC Value #1       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    Mask = 0   |          Origination Point Code #2            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Lower CIC Value #2      |      Upper CIC Value #2       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                              ...                              /
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    Mask = 0   |          Origination Point Code #n            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Lower CIC Value #n      |      Upper CIC Value #n       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

3.6.2 Registration Response (REG RSP)

   The REG RSP message is used as a response to the REG REQ message from
   a remote M3UA peer.  It contains indications of success/failure for
   registration requests and returns a unique Routing Context value for
   successful registration requests, to be used in subsequent M3UA
   Traffic Management protocol.

   The REG RSP message contains the following parameters:

   Registration Result   Mandatory

   One or more Registration Result parameters MUST be included.  The
   format for the REG RSP message is as follows:

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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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x0208         |              Length           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Registration Result 1                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                              ...                              /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Tag = 0x0208        |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Registration Result n                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Registration Results:

      The Registration Result parameter contains the registration result
      for a single Routing Key in an REG REQ message.  The number of
      results in a single REG RSP message MUST be anywhere from one to
      the total number of number of Routing Key parameters found in the
      corresponding REG REQ message.  Where multiple REG RSP messages
      are used in reply to REG REQ message, a specific result SHOULD be
      in only one REG RSP message.  The format of each result is as
      follows:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x020a        |          Length = 8             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Local-RK-Identifier value                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Tag = 0x0212      |          Length = 8             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      Registration Status                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Tag = 0x0006      |          Length = 8             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Routing Context                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Local-RK-Identifier: 32-bit integer

      The Local-RK-Identifier contains the same value as found in the
      matching Routing Key parameter found in the REG REQ message (See
      Section 3.6.1).

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   Registration Status: 32-bit integer

      The Registration Result Status field indicates the success or the
      reason for failure of a registration request.

      Its values may be:

         0           Successfully Registered
         1           Error - Unknown
         2           Error - Invalid DPC
         3           Error - Invalid Network Appearance
         4           Error - Invalid Routing Key
         5           Error - Permission Denied
         6           Error - Cannot Support Unique Routing
         7           Error - Routing Key not Currently Provisioned
         8           Error - Insufficient Resources
         9           Error - Unsupported RK parameter Field
         10          Error - Unsupported/Invalid Traffic Handling Mode

   Routing Context: 32-bit integer

      The Routing Context field contains the Routing Context value for
      the associated Routing Key if the registration was successful.  It
      is set to "0" if the registration was not successful.

3.6.3 Deregistration Request (DEREG REQ)

   The DEREG REQ message is sent by an ASP to indicate to a remote M3UA
   peer that it wishes to deregister a given Routing Key.  Typically, an
   ASP would send this message to an SGP, and expects to receive a DEREG
   RSP message in return with the associated Routing Context value.

   The DEREG REQ message contains the following parameters:

      Routing Context       Mandatory

   The format for the DEREG REQ message is as follows:

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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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0006          |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                       Routing Context                         /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Routing Context: n X 32-bit integers

      The Routing Context parameter contains (a list of) integers
      indexing the Application Server traffic that the sending ASP is
      currently registered to receive from the SGP but now wishes to
      deregister.

3.6.4 Deregistration Response (DEREG RSP)

   The DEREG RSP message is used as a response to the DEREG REQ message
   from a remote M3UA peer.

   The DEREG RSP message contains the following parameters:

      Deregistration Result    Mandatory

   One or more Deregistration Result parameters MUST be included.  The
   format for the DEREG RSP message is as follows:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x0209         |               Length          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Deregistration Result 1                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                                                               \
      /                              ...                              /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Tag = 0x0209        |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Deregistration Result n                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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   Deregistration Results:

      The Deregistration Result parameter contains the deregistration
      status for a single Routing Context in a DEREG REQ message.  The
      number of results in a single DEREG RSP message MAY be anywhere
      from one to the total number of number of Routing Context values
      found in the corresponding DEREG REQ message.

      Where multiple DEREG RSP messages are used in reply to DEREG REQ
      message, a specific result SHOULD be in only one DEREG RSP
      message.  The format of each result is as follows:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0006          |          Length = 8           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Routing Context                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0213          |          Length = 8           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     Deregistration Status                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Routing Context: 32-bit integer

      The Routing Context field contains the Routing Context value of
      the matching Routing Key to deregister, as found in the DEREG REQ
      message.

      Deregistration Status: 32-bit integer

      The Deregistration Result Status field indicates the success or
      the reason for failure of the deregistration.

      Its values may be:

         0           Successfully Deregistered
         1           Error - Unknown
         2           Error - Invalid Routing Context
         3           Error - Permission Denied
         4           Error - Not Registered
         5           Error - ASP Currently Active for Routing Context


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