rfc3033.txt

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        |   Length of contents of information element   |  3-4
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |    Identifier related standard/application    |  5
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |                Identifier type                |  6
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |               Identifier length               |  7
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |                Identifier value               |  8-
        =                                               =
        +-----+-----+-----+-----+-----+-----+-----+-----+
        =                                               =
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |                Identifier type                |
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |               Identifier length               |
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |                Identifier value               |
        =                                               =
        +-----+-----+-----+-----+-----+-----+-----+-----+

      Fig. 3.1: Format of the Generic Identifier information element.

   The usage of the first 4 octets of fields is specified in section 4
   of the Q.2931.

   The Identifier related standard/application field identifies the
   standard or application that uses the identifier.  Assignment of the
   Identifier related standard/application field for the Internet
   protocol is as follows.  A leading 0x means hexadecimal.

     0x03: IPv4.

     0x04: ST2+.

     0x05: IPv6.

     0x06: MPLS.




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   Note: DSM-CC, H.310/H.321, MPOA, ATM VCC Trunking, AAL2, and
   H.323/H.245 are also supported.

   A transferred identifier is given by the combination of the
   Identifier type, length and value fields, and a Generic Identifier
   information element may contain multiple identifiers.

   Assignment of the Identifier type field for the Internet protocol is
   as follows.  A leading 0x means hexadecimal.

     0x01: Session.

     0x02: Resource.

     0x10-0xFD: Reserved for IANA assignment.

     0xFE: Experiment/Organization specific.

   The maximum length of the Generic Identifier information element is
   63 octets.

   See the Q.2941.1 and Draft Q.2941.2 for detailed protocol
   specifications of the Generic Identifier.

3.2 Overview of the User-to-user Signaling

   The User-to-user Signaling enables the transfer of information
   between end-to-end users in the ATM network, and it is defined in
   Q.2957 [5, 6] and in Q.2971 annex D [2] as an optional information
   element for the Q.2931 [1] and Q.2971 [2] UNI signaling protocol.
   The SETUP, ALERTING, CONNECT, RELEASE, RELEASE COMPLETE, PROGRESS,
   ADD PARTY, PARTY ALERTING, ADD PARTY ACK, ADD PARTY REJECT, DROP
   PARTY, and DROP PARTY ACK messages that are transferred between end-
   to-end users in the ATM network may contain a User-user information
   element.  The ATM network transfers the User-user information element
   transparently if it contains no coding rule errors.

   From the viewpoint of B-ISDN signaling applications, it seems the
   Generic Identifier and User-to-user Signaling are similar functions.
   But their rules for processing exceptions are not completely the
   same, because their purposes are different.  The Generic Identifier
   is designed for the transfer of identifiers between the c-planes,
   while the User-to-user Signaling is designed for the transfer of user
   data via the c-planes.  Another difference is that the latter
   supports interworking with the user-user information element in the






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   Q.931 N-ISDN signaling, but the Generic Identifier does not.  Note
   that the ATM network may check the contents of the Generic Identifier
   information element, but does not check the contents of the User-to-
   user information element.

   The format of the User-user information element is shown in Fig. 3.2.

                              Bits
           8     7     6     5     4     3     2     1    Octets
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |        Information element identifier         |
        |    = User-user information element (0x7E)     |  1
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |  1  |   Coding  |    IE instruction field     |
        | Ext |  standard |Flag |Res. |  IE action ind. |  2
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |   Length of contents of information element   |  3-4
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |             Protocol discriminator            |  5
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |               User information                |  6-
        =                                               =
        |                                               |
        +-----+-----+-----+-----+-----+-----+-----+-----+

      Fig. 3.2: Format of the User-user information element.

   The usage of the first 4 octets of fields is specified in section 4
   of the Q.2931.

   The Protocol discriminator field identifies the upper layer protocol
   that uses the user-user information.

   The User information field contains the user-user information to be
   transferred.

   The maximum length of the User-user information element is 133
   octets.

   See Q.2957, Draft Q.2957 amendment 1, and Q.2971 annex D for detailed
   protocol specifications of the User-to-user Signaling.










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4. Information Field and Protocol Identifier Assignment

4.1 Assignment in the Generic Identifier Information Element

4.1.1 Use of Generic Identifier

   The information field and protocol identifier assignment principle
   for the Internet protocol in the Generic Identifier information
   element is shown in Fig. 4.1.

                              Bits
           8     7     6     5     4     3     2     1    Octets
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |        Information element identifier         |
        |    = Generic identifier transport IE (0x7F)   |  1
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |  1  |   Coding  |    IE instruction field     |
        | Ext |  standard |Flag |Res. |  IE action ind. |  2
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |   Length of contents of information element   |  3-4
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |    Identifier related standard/application    |
        |          = IPv4, ST2+, IPv6, or MPLS          |  5
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |                Identifier type                |
        |       = Session, Resource, or Experiment   |  6
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |               Identifier length               |  7
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |                Identifier value               |  8-
        =                                               =
        +-----+-----+-----+-----+-----+-----+-----+-----+
        =                                               =
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |                Identifier type                |
        |       = Session, Resource, or Experiment   |
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |               Identifier length               |
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |                Identifier value               |
        =                                               =
        +-----+-----+-----+-----+-----+-----+-----+-----+

      Fig. 4.1: Principle of assignment in the Generic Identifier
                information element.

   The Identifier related standard/application field is the IPv4, ST2+,
   IPv6, or MPLS.



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   The Identifier type field is the Session, Resource, or
   Experiment/Organization specific.

   The Identifier value field is assigned to Internet protocol related
   information which is identified by the Identifier related
   standard/application field and Identifier type field.  The following
   identifiers are specified.

                                     Std./app.               Id type

     IPv4 session identifier         IPv4                    Session

     IPv6 session identifier         IPv6                    Session

     MPLS VCID                       MPLS                    Resource

     Exp./Org. specific              IPv4/ST2+/IPv6/MPLS     Experiment

   As described in section 3.1, the B-ISDN signaling message transferred
   between end-to-end users may contain up to three Generic Identifier
   information elements.  These elements may contain multiple
   identifiers.  This document does not specify the order of identifiers
   when multiple identifiers appear in a signaling message.

   This document also does not specify the semantics when multiple
   identifiers having the same Identifier type appear in a signaling
   message, or when a signaling message contains a Generic Identifier
   information element that does not contain identifiers.

   When a B-ISDN signaling message containing a Generic Identifier
   information element enters an ATM network that does not support the
   Generic Identifier, the network clears the call, discards the
   information element, or discards the signaling message.  (See
   sections 4.5.1 and 5.6.8.1 of Q.2931 and section 9.3 of Q.2941.1 for
   details.)

   To enable reliable Generic Identifier information element transfer,
   when the calling party sends a SETUP or ADD PARTY message with up to
   three Generic Identifier information elements, the CONNECT or ADD
   PARTY ACK message returned by the called party must contain at least
   one Generic Identifier information element.  The called party may not
   respond with the same identifiers received from the calling party.
   The calling party should confirm that the response message contains
   at least one Generic Identifier information element.  This rule
   enables identifier negotiation; this document does not specify the
   detailed procedure of this negotiation.





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4.1.2 IPv4 session identifier

   If the Identifier related standard/application field in the Generic
   Identifier information element is the IPv4, and the Identifier type
   field in the identifier is the Session, the identifier is the IPv4
   session identifier.  The format of the IPv4 session identifier is
   shown in Fig. 4.2.

                              Bits                         Octet
           8     7     6     5     4     3     2     1     length
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |                Identifier type                |
        |                = Session (0x01)               |  1
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |               Identifier length               |
        |               = 13 octets (0x0D)              |  1
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |              Source IPv4 address              |  4
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |           Destination IPv4 address            |  4
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |                   Protocol                    |  1
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |                  Source Port                  |  2
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |                Destination Port               |  2
        +-----+-----+-----+-----+-----+-----+-----+-----+

      Fig. 4.2: IPv4 session identifier.

   The Identifier type field is the Session (0x01).

   The Identifier length is 13 octets.

   The Source IPv4 address, Destination IPv4 address, Protocol, Source
   Port, and Destination Port [7, 9, 10] are assigned in that order to
   the Identifier value field.

   Note: This specific session identifier is intended for use only with
   the explicit reservation.  If wild card associations are needed at a
   later date, another identifier type will be used.

4.1.3 IPv6 session identifier

   If the Identifier related standard/application field in the Generic
   Identifier information element is the IPv6, and the Identifier type
   field in the identifier is the Session, the identifier is the IPv6
   session identifier.  The format of the IPv6 session identifier is



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   shown in Fig. 4.3.

                              Bits                         Octet
           8     7     6     5     4     3     2     1     length
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |                Identifier type                |
        |                = Session (0x01)               |  1
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |               Identifier length               |
        |               = 37 octets (0x25)              |  1
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |              Source IPv6 address              |  16
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |           Destination IPv6 address            |  16
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |                   Protocol                    |  1
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |                  Source Port                  |  2
        +-----+-----+-----+-----+-----+-----+-----+-----+
        |                Destination Port               |  2
        +-----+-----+-----+-----+-----+-----+-----+-----+

      Fig. 4.3: IPv6 session identifier.