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draft-bidulock-sigtran-sginfo-01

Description: Request For Comments

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Listed below is the contents of file draft-bidulock-sigtran-sginfo-01.txt.




Network Working Group                                     Brian Bidulock
INTERNET-DRAFT                                       OpenSS7 Corporation

Expires in six months                                 September 15, 2002

          Signalling Gateway (SG) Information (SGINFO) Support
                                  for
                   Signalling User Adaptation Layers
                 <draft-bidulock-sigtran-sginfo-01.txt>

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 or RFC 2026.  Internet-Drafts are
   working documents of the Internet Engineering Task Force (IETF), its
   areas, and its working groups.  Note that other groups may also
   distribute working documents as Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as 'work in progress'.

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html

   To learn the current status of any Internet-Draft, please check the
   Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe),
   munnari.oz.au (Pacific Rim), ftp.ietf.org (US East Coast), or
   ftp.isi.edu (US West Coast).

Abstract

   This Internet-Draft describes Signalling Gateway (SG) Information
   (SGINFO) for Signalling User Adaptation Protocols [M2UA, M3UA, SUA,
   TUA], which permits supporting Signalling Gateways (SG) to convey
   additional Application Server (AS) support information to Application
   Server Processes (ASPs) activating for AS on the SG.  This additional
   AS support information consists of information pertaining to the
   underlying SS7 Signalling Provider that otherwise would have to be
   statically configured at the Application Server Process (ASP) or
   exchanged between SG and ASP using a non-IETF defined protocol.

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1.  Introduction

1.1.  Scope

   This Internet-Draft provides parameters and procedures in extension
   to the parameters and procedures of the Signalling User Adaptation
   Layers (UAs) [M2UA, M3UA, SUA, TUA], for the purpose of supporting
   the transfer of SG-specific information of interest to an Application
   Server during the ASP Active procedure.

   UA implementations with SGINFO are intended to be compatible with UA
   implementations not supporting this configuration.

1.2.  Terminology

   SGINFO adds the following terms to the terminology presented in the
   UA documents: [1]

   Signalling User Adaptation Layer (UA) - one or more of the Stream
         Control Transmission Protocol (SCTP) [RFC 2960] SS7 Signalling
         User Adaptation Layers [M2UA, M3UA, SUA, TUA] supporting the
         concept of a ASP Management.

1.3.  Overview

   There is a need to provide extensions for the Signalling User
   Adaptation Layer protocols to permit a Signalling Gateway (SG) to
   provide Application Server (AS) specific information pertaining to
   the SG's ability to support the Application Server.

   For example, the "Maximum SIF Length" of MTP3 [Q.704] is a value that
   an MTP-User at an AS needs to reference to avoid sending MSU data in
   excess of these MTP-PDU length restrictions.  The "Maximum SIF
   Length"; however, can change due to SS7 Network failures or
   reconfiguration at the SG that cannot be handled purely by static
   configuration information at an ASP.

   Additional examples exist for SCCP [Q.711] and TCAP [Q.771] and the
   need for these protocol limits at the Application Server is evidenced
   by the requirements for these values in the OSI/ISO NSD [X.213]
   Compliant NPI [NPI], and the OSI/ISO TSD [X.214] and the OSI/ISO ROSE
   [X.219] Compliant TPI [TPI], and the ACSE [ISO 8649, ISO 8650]
   compliant mOSI extensions to the XNS [XNS].

   SGINFO provides parameters and procedures that allow Signalling
   Gateway Processes (SGPs) to inform Application Server Processes
   (ASPs) of the SG parameters, as well as provides procedures to update
   these parameters in an active AS.

1.3.1.  Existing Information Management

   While there is a mandate to provide MIBs to support UA configuration,
   the existing UA procedures[2] and MIBs make no provisions for the
   management of dynamic operational information at a Signalling Gateway

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   that is of specific concern to a UA-User at an Application Server
   (AS).

   For example, if an Signalling Gateway changes an operation parameter
   of necessary to an UA-User at an Application Server (AS), such as the
   "Maximum SIF Length", there is no mechanism for the SG to communicate
   this information to the concerned Application Server (AS).

   While the existing UA procedures[2] provide for the SG giving an
   indication of a "Protocol Error" or "Invalid Parameter Value" as a
   result of an operational parameter being exceeded, there are no
   procedures for the Application Server to discover the operational
   parameters when they are dynamic.

   The lack of an IETF procedure for managing operational parameter
   information represents a deficiency of the existing UA procedures[2]
   that detracts from interoperability between separate implementations
   of SGP and ASP.

1.3.2.  SGINFO Information Management

   To remedy these deficiencies, SGINFO provides support for the
   following:

    - Support for an SG indicating operational parameters to an
      Application Server (AS).
    - Support for an SG changing operational parameter for an active
      Application Server (AS).
    - Support for interworking between SGPs supporting SGINFO and ASPs
      not supporting SGINFO.

2.  Conventions

   The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
   SHOULD NOT, RECOMMENDED, NOT RECOMMENDED, MAY, and OPTIONAL, when
   they appear in this document, are to be interpreted as described in
   [RFC 2119].

3.  Protocol Elements

   SGINFO provides the following parameters and the messages in which
   they are included in addition to the parameters of the UAs.[3]

3.1.  Parameters

   SGINFO provides the following parameters in addition to the
   parameters defined for the UAs.[3]

3.1.1.  Protocol Limits

   The Protocol Limits parameter is a common parameter used in the ASPAC
   ACK message to indicate the protocol data unit size limitations
   presented by a Signalling Gateway to an Application Server.

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   The Protocol Limits parameter is formatted 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 = 0xXXXX          |            Length             |
     +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
     |                        Maximum SDU Size                       |
     +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
     |                   Optimal SDU Size (optional)                 |
     +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
     |              Maximum Connect Data Size (optional)             |
     +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
     |             Maximum Disconnect Data Size (optional)           |
     +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
     |                  Maximum ESDU Size (optional)                 |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       EDITOR'S NOTE:-  The parameter tag values shown as 0xXXXX
       above will be assigned by IANA within the common parameter
       range of the SIGTRAN UAs and may change its value in further
       versions of this document.

   The Protocol Limits parameter contains the following fields:

   Maximum SDU Size field: 32-bits (signed integer)

     The Maximum SDU Size field contains the maximum number of bytes in
     the Protocol Data parameter that the Signalling Gateway can support
     to the specific Application Server.

     M2UA  For M2UA [M2UA] the Maximum SDU Size field provides the
           maximum size of the data payload of the Protocol Data field.
           The maximum size is the largest maximum data payload size
           that can be transferred across the SS7 network by the SG for
           the specified link.  For example, for an SG supporting an SIF
           Maximum Size [Q.704] of 3094 bytes on the link, this size
           would be 3094.  For an SG supporting 272 bytes, this size
           would be 272.

     M3UA  For M3UA [M3UA] the Maximum SDU Size field provides the limit
           on the maximum size of the data payload of the Protocol Data
           field.  The maximum size is the largest maximum data payload
           size that can be transferred across the SS7 network by the SG
           for the specific Application Server.  For example, for an SG
           supporting both an SIF Maximum Size [Q.704] of 3094 bytes on
           a primary links and 272 bytes on secondary links, this size
           would be 3094.

     SUA   For SUA [SUA] the Maximum SDU Size field provides the limit
           on the maximum size of the User Data field for a normal (non-
           expedited) data transfer.  The maximum size is the largest

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           data payload size that can be transferred across the SS7
           network for the specific Application Server (and associated
           Protocol Class) considering segmentation.  If there is no
           limit on the NSDU size for an SCCP provider at an SG, this
           field will be set to a value of -1.

     TUA   For TUA [TUA] the Maximum SDU Size field provide the limit on
           the maximum size of the Components field for a TC-CONTINUE
           data transfer.  The maximum size is the largest component
           size that can be transferred across the SS7 network for the
           specific Application Server (and associated Operation Class)
           considering segmentation.  If there is no limit on the
           component size for a TCAP provider at the SG, this field will
           be set to a value of -1.

   Optimal SDU Size field: 32-bits (signed integer)

     The Optimal SDU Size field contains the optimal number of bytes in
     the Protocol Data parameter that the Signalling Gateway can support
     to the specific Application Server.

     M2UA  For M2UA [M2UA] the Optimal SDU Size field does not apply and
           is not included in the Protocol Limits parameter.

     M3UA  For M3UA [M3UA] the Optimal SDU Size field provides the limit
           on the optimal size of the data payload of the Protocol Data
           field.  The optimal size is the smallest maximum data payload
           size that can be transferred across the SS7 network by the SG
           for the specific Application Server.  For example, for an SG
           supporting both an SIF Maximum Size [Q.704] of 3094 bytes on
           a primary links and 272 bytes on secondary links, this size
           would be 272.

     SUA   For SUA [SUA] the Optimal SDU Size field provides the limit
           on the optimal size of the User Data field for a normal (non-
           expedited) data transfer.  The optimal size is the largest
           data protocol size that can be transferred across the SS7
           network for the specific Application Server (and associated
           Protocol Class) without segmentation.

     TUA   For TUA [TUA] the Optimal SDU Size field provides the limit
           on the optimal size of the Components field for a TC-CONTINUE
           data transfer.  The optimal size is the largest component
           size that can be transferred across the SS7 network for the
           specific Application Server (and associated Operation Class)
           without segmentation.

   Maximum Connect Data Size field: 32-bits (signed integer)

     The Maximum Connect Data Size field contains the maximum number of
     bytes in the Data parameter that the Signalling Gateway can support
     to the specific Application Server upon connection or transaction
     dialogue establishment.

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     M2UA  For M2UA [M2UA] the Maximum Connect Data Size field does not
           apply and is not included in the Protocol Limits parameter.

     M3UA  For M3UA [M3UA] the Maximum Connect Data Size field does not
           apply and is not included in the Protocol Limits parameter.

     SUA   For SUA [SUA] the Maximum Connect Data Size field provides a
           limit on the maximum size of the User Data field that can be
           included in CORE and COAK messages.  For Connection-less
           operation, this field does not apply and is not included in
           the Protocol Limits parameter.

     TUA   For TUA [TUA] the Maximum Connect Data Size field provides
           the limit on the maximum size of the User Information and
           Components that can be included in a TQRY or initial TCNV
           message.  For Operation Class 4, this field does not apply
           and is not included in the Protocol Limits parameter.

   Maximum Disconnect Data Size field: 32-bits (signed integer)

     The Maximum Disconnect Data Size field contains the maximum number
     of bytes in the Data parameter that the Signalling Gateway can
     support to the specific Application Server upon disconnection or
     transaction dialogue abort.

     M2UA  For M2UA [M2UA] the Maximum Disconnect Data Size field deos
           not apply and is not included in the Protocol Limits
           parameter.

     M3UA  For M3UA [M3UA] the Maximum Disconnect Data Size field does
           not apply and is not included in the Protocol Limits
           parameter.

     SUA   For SUA [SUA] the Maximum Disconnect Data Size field provides
           a limit on the maximum size of the User Data field that can
           be included in a RELRE message.  For Connection-less
           operation, this field does not apply and is not included in
           the Protocol Limits parameter.

     TUA   For TUA [TUA] the Maximum Disconnect Data Size field provides
           the limit on the maximum size of the User Abort Information
           that can be included in a TUAB message.  For Operation Class
           4, this field does not apply and is not included in the
           Protocol Limits parameter.

   Maximum ESDU Size field: 32-bits (signed integer)

     The Maximum ESDU Size field contains the maximum number of bytes in
     the Data parameter that the Signalling Gateway can support to the
     specific Application Server when data is expedited on a connection.

     M2UA  For M2UA [M2UA] The Maximum ESDU Size field does not apply
           and is not included in the Protocol Limits parameter.

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     M3UA  For M3UA [M3UA] the Maximum ESDU Size field does not apply
           and is not included in the Protocol Limits parameter.

     SUA   For SUA [SUA] the Maximum ESDU Size field provides a maximum
           number of bytes in the User Data field for an expedited data
           transfer.  The maximum size is the largest expedited data
           payload size that can be transferred across the SS7 network
           for the specific Application Server.  For Connection-less or
           Protocol Class 2 operation, this field does not apply and is
           not included in the Protocol Limits parameter.

     TUA   For TUA [TUA] the Maximum ESDU Size field does not apply and
           is not included in the Protocol Limits parameter.

3.2.  Messages

   SGINFO extends the following messages defined for the UAs.[3]

3.2.1.  ASP Active Acknowledgment (ASPAC ACK)

   SGINFO supplements the ASPAC ACK message by permitting the following
   optional parameters to be included in the message:

       Extension Parameters
       -----------------------------------------
       Protocol Limits             Optional

   The format of the resulting ASP ACK message for M2UA 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 = 0xXXXX          |            Length             |
     +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
     \                                                               \
     /                        Protocol Limits                        /
     \                                                               \
     +-------------------------------+-------------------------------+
     |         Tag = 0x0004          |            Length             |
     +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
     \                                                               \
     /                           Info String                         /
     \                                                               \
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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       EDITOR'S NOTE:-  The parameter tag values shown as 0xXXXX
       above will be assigned by IANA within the common parameter
       range of the SIGTRAN UAs and may change its value in further
       versions of this document.

   The format of the resulting ASPAC ACK message for M3UA, SUA and TUA
   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 = 0x000b          |            Length = 8         |
     +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
     |                       Traffic Mode Type                       |
     +-------------------------------+-------------------------------+
     |         Tag = 0x0001          |            Length             |
     +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
     \                                                               \
     /                    Interface Identifiers                      /
     \                                                               \
     +-------------------------------+-------------------------------+
     |         Tag = 0x0008          |            Length             |
     +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
     |                  Interface Identifier Start1                  |
     +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
     |                   Interface Identifier Stop1                  |
     +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
     |                  Interface Identifier Start2                  |
     +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
     |                   Interface Identifier Stop2                  |
     +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
     \                               .                               \
     /                               .                               /
     \                               .                               \
     +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
     |                  Interface Identifier StartN                  |
     +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
     |                   Interface Identifier StopN                  |
     +---------------------------------------------------------------+
     /                                                               /
     \               Additional Interface Identifiers                \
     /                     of Tage Type 0x1 or 0x8                   /
     \                                                               \
     +-------------------------------+-------------------------------+
     |         Tag = 0xXXXX          |            Length             |
     +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
     \                                                               \
     /                        Protocol Limits                        /
     \                                                               \
     +-------------------------------+-------------------------------+
     |         Tag = 0x0004          |            Length             |
     +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
     \                                                               \
     /                           Info String                         /
     \                                                               \
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       EDITOR'S NOTE:-  The parameter tag values shown as 0xXXXX
       above will be assigned by IANA within the common parameter
       range of the SIGTRAN UAs and may change its value in further
       versions of this document.

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   No other changes to the ASPAC ACK message format are provided by this
   extension.

   To indicate restrictions on the maximum sizes for transfer of data,
   the SGP and IPSP MUST include the Protocol Limits parameter in the
   ASPAC ACK message.

4.  Procedures

   The following procedures are provided in extension to the UA
   procedures by SGINFO.

4.1.  ASP Management Procedures

4.1.1.  ASP Active Procedures

   In extension of the "ASP Active Procedures" of the UAs[2], SGINFO
   provides the following procedures:

   Whenever an SGP, as a part of the normal UA procedures, sends an ASP
   Active Acknowledgment (ASPAC ACK) to an ASP, it MAY include the
   Protocol Limits parameter indicating the protocol data size limits
   that apply to the Application Server associated with the Routing
   Context(s)/Interface Identifier(s) specified or implied in the ASPAC
   ACK message.  Where the protocol limits only apply to one Application
   Server, the SGP SHOULD NOT include more than one Routing
   Context/Interface Identifier in the ASPAC ACK response.  That is, in
   response to an ASPAC message containing multiple Routing
   Contexts/Interface Identifiers, the SGP SHOULD send a separate ASPAC
   ACK reply for each Routing Context/Interface Identifier for which it
   includes the Protocol Limits parameter.

   If an SG discovers that the protocol data size limits has changed due
   to an event, (such as a failure in the SS7 network), the SGP MAY send
   an unsolicited ASPAC ACK message containing the new protocol limits.

   Whenever an ASP receives an ASPAC ACK message as part of the normal
   UA procedures, or receives an unsolicited ASPAC ACK for an active
   Application Server (AS), the ASP will apply the new protocol data
   size limits to the Application Server.

4.2.  Interworking

   Whenever an SGP receives an ERR("Invalid Parameter") message
   indicating the Protocol Limits parameter in response to a sent ASPAC
   ACK message containing a Protocol Limits parameter, the SGP SHOULD
   re-attempt by sending the ASPAC ACK without a Protocol Limits
   parameter.

5.  Examples

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5.1.  ASP and SGP both supporting Protocol Limits

   An example of an ASP and SGP both supporting Protocol Limits is
   illustrated in Figure 1.

   As illustrated in Figure 1, the sequence of events for this example
   are as follows:

    (1)   An Application Server at an ASP begins in the AS-DOWN or AS-
          INACTIVE state.

    (2)   The ASP activates an Application Server by sending an ASPAC
          message.

    (3)   The SGP responds with an ASPAC ACK message containing the
          current protocol limits in the Protocol Limits parameter.  The
          ASP applies these protocol limits to the Application Server
          upon activation.

    (4)   Later, when the SGP notes a change to protocol limits, the SGP
          sends an unsolicited ASPAC ACK message containing the updated
          Protocol Limits.  The ASP applies these updated protocol
          limits to the Application Server upon receipt.

5.2.  SGP only supporting Protocol Limits

5.2.1.  ASP ignores Protocol Limits

   An example of an SGP only supporting Protocol Limits where the ASP
   ignores the Protocol Limits parameter is illustrated in Figure 2.

                       SGP                             ASP
                        |            ASPUP              |
                        |<------------------------------|
                        |          ASPUP ACK            |
                (1)     |------------------------------>|
                        |                               |
                        |            ASPAC              |
                (2)     |<------------------------------|
                        |                               |
                        |   ASPAC ACK(Protocol Limits)  |
                (3)     |------------------------------>|
                        |                               |
                        .                               .
                        .                               .
                        .                               .
                        |   ASPAC ACK(Protocol Limits)  |
                (4)     |------------------------------>|
                        |                               |

         Figure 1.  ASP and SGP both supporting Protocol Limits

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                       SGP                             ASP
                        |            ASPUP              |
                        |<------------------------------|
                        |          ASPUP ACK            |
                (1)     |------------------------------>|
                        |                               |
                        |            ASPAC              |
                (2)     |<------------------------------|
                        |                               |
                        |   ASPAC ACK(Protocol Limits)  |
                (3)     |------------------------------>|
                        |                               |
                        .                               .
                        .                               .
                        .                               .
                        |   ASPAC ACK(Protocol Limits)  |
                (4)     |------------------------------>|
                        |                               |

         Figure 2.  ASP and SGP both supporting Protocol Limits

   As illustrated in Figure 2, the sequence of events for this example
   are as follows:

    (1)   An Application Server at an ASP begins in the AS-DOWN or AS-
          INACTIVE state.

    (2)   The ASP activates an Application Server by sending an ASPAC
          message.

    (3)   The SGP responds with an ASPAC ACK message containing the
          current protocol limits in the Protocol Limits parameter.  The
          ASP ignores the Protocol Limits parameter and, instead, relies
          upon internal configuration data to determine protocol limits.

    (4)   Later, when the SGP notes a change to protocol limits, the SGP
          sends an unsolicited ASPAC ACK message containing the updated
          Protocol Limits.  The ASP ignores the Protocol Limits
          parameter and, instead, relies upon internal configuration
          data to determine protocol limits.

5.2.2.  ASP refuses Protocol Limits

   An example of an SGP only supporting Protocol Limits where the ASP
   refuses the Protocol Limits parameter is illustrated in Figure 3.

   As illustrated in Figure 3, the sequence of events for this example
   are as follows:

    (1)   An Application Server at an ASP begins in the AS-DOWN or AS-
          INACTIVE state.

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                       SGP                             ASP
                        |            ASPUP              |
                        |<------------------------------|
                        |          ASPUP ACK            |
                (1)     |------------------------------>|
                        |                               |
                        |            ASPAC              |
                (2)     |<------------------------------|
                        |                               |
                        |   ASPAC ACK(Protocol Limits)  |
                (3)     |------------------------------>|
                        |                               |
                        |    ERR("Invalid Parameter")   |
                (4)     |<------------------------------|
                        |                               |
                        |          ASPAC ACK            |
                (5)     |------------------------------>|
                        |                               |
                        .                               .
                        .                               .
                        .                               .
                        |                               |
                (6)     |                               |
                        |                               |

         Figure 3.  ASP and SGP both supporting Protocol Limits

    (2)   The ASP activates an Application Server by sending an ASPAC
          message.

    (3)   The SGP responds with an ASPAC ACK message containing the
          current protocol limits in the Protocol Limits parameter.

    (4)   The ASP refuses the ASPAC ACK message and responds with an
          ERR("Invalid Parameter") message indicating the Protocol
          Limits parameter as invalid.

    (5)   The SGP re-attempts and sends the ASPAC ACK message without
          the Protocol Limits parameter and marks the ASP as incapable
          of processing protocol limits.

    (6)   When a subsequent change in the protocol limits at the SGP
          occurs, the SGP does nothing (the ASP is marked as incapable
          of handling protocol limits).

5.3.  ASP only supporting Protocol Limits

   An example of an ASP only supporting Protocol Limits is illustrated
   in Figure 4.

   As illustrated in Figure 4, the sequence of events for this example
   are as follows:

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                       SGP                             ASP
                        |            ASPUP              |
                        |<------------------------------|
                        |          ASPUP ACK            |
                (1)     |------------------------------>|
                        |                               |
                        |            ASPAC              |
                (2)     |<------------------------------|
                        |                               |
                        |          ASPAC ACK            |
                (3)     |------------------------------>|
                        |                               |
                        |                               |
                (4)     |                               |
                        |                               |

         Figure 4.  ASP and SGP both supporting Protocol Limits

    (1)   An Application Server at an ASP begins in the AS-DOWN or AS-
          INACTIVE state.

    (2)   The ASP activates an Application Server by sending an ASPAC
          message.

    (3)   The SGP responds with an ASPAC ACK message not containing the
          Protocol Limits parameter.

    (4)   The ASP receiving the ASPAC ACK with no Protocol Limits
          parameter relies upon internal configuration data to determine
          protocol limits.

6.  Security

   SGINFO does not introduce any new security risks or considerations
   that are not already inherent in the UA [M2UA, M3UA, SUA, TUA] Please
   see the "Security" sections of M2UA [M2UA], M3UA [M3UA], SUA [SUA]
   and TUA [TUA], for security considerations and recommendations that
   are applicable to each of these UAs.

7.  IANA Considerations

7.1.  Protocol Extensions

   SGINFO provides an additional Protocol Limits message parameter to
   the common parameter range of the SIGTRAN UAs [M2UA, M3UA, SUA, TUA]:

    (a)   The parameter is named the Protocol Limits parameter.

    (b)   The structure of the Protocol Limits parameter field conforms
          to the UA general TLV format and is described in detail in
          Section 3.1.1.

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    (c)   The detailed definition of each component of the Protocol
          Limits parameter values is described in Section 3.1.1.

    (d)   This document also provides a detailed description of the
          intended use of the Protocol Limits parameter, and in which
          messages the Protocol Limits parameter should appear, how many
          times, and when.

       EDITOR'S NOTE:-  The Protocol Limits parameter tag value
       shown throughout this document as 0xXXXX will be assigned by
       IANA within the common parameter range of the SIGTRAN UAs and
       may change its value in further versions of this document.

End Notes

   [1]  See, for example, Section 1.2 of M2UA, M3UA, SUA or TUA [M2UA,
        M3UA, SUA, TUA].

   [2]  See, for example, Section 4 of M2UA, M3UA, SUA or TUA [M2UA,
        M3UA, SUA, TUA].

   [3]  See, for example, Section 3 of the M2UA, M3UA, SUA or TUA [M2UA,
        M3UA, SUA, TUA].

References

   M2UA.
        K. Morneault, R. Dantu, G. Sidebottom, B. Bidulock and J. Heitz,
        "Signaling System 7 (SS7) Message Transfer Part 2 (MTP2) - User
        Adaptation Layer," RFC 3331, Internet Engineering Task Force -
        Signalling Transport Working Group (September, 2002).

   M3UA.
        G. Sidebottom, K. Morneault and J. Pastor-Balbas, (eds),
        "Signaling System 7 (SS7) Message Transfer Part 3 (MTP3) - User
        Adaptation Layer (M3UA)," RFC 3332, Internet Engineering Task
        Force - Signalling Transport Working Group (September, 2002).

   SUA.
        J. Loughney, G. Sidebottom, L. Coene, G. Verwimp, J. Keller and
        B. Bidulock, "SS7 SCCP-User Adaptation Layer (SUA)," <draft-
        ietf-sigtran-sua-14.txt>, Internet Engineering Task Force -
        Signalling Transport Working Group (June 30, 2002).  Work In
        Progress.

   TUA.
        B. Bidulock, "SS7 TCAP-User Adaptation Layer (TUA)," <draft-
        bidulock-sigtran-tua-01.txt>, Internet Engineering Task Force -
        Signalling Transport Working Group (January 2, 2003).  Work In
        Progress.

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   RFC 2960.
        R. Stewart, Q. Xie, K. Morneault, C. Sharp, H. J. Schwarzbauer,
        T. Taylor, I. Rytina, H. Kalla, L. Zhang and V. Paxson, "Stream
        Control Transmission Protocol (SCTP)," RFC 2960, The Internet
        Society (February 2000).

   Q.704.
        ITU, "Message Transfer Part - Signalling Network Functions and
        Messages," ITU-T Recommendation Q.704, ITU-T Telecommunication
        Standardization Sector of ITU, Geneva (March 1993).  (Previously
        "CCITT Recommendation")

   Q.711.
        ITU, "Functional Description of Signalling Connection Control
        Part," ITU-T Recommendation Q.711, ITU-T Telecommunication
        Standardization Sector of ITU, Geneva (March 1993).  (Previously
        "CCITT Recommendation")

   Q.771.
        ITU, "Signalling System No. 7 - Functional Description of
        Transaction Capabilities," ITU-T Recommendation Q.771, ITU-T
        Telecommunication Standardization Sector of ITU, Geneva (March
        1993).  (Previously "CCITT Recommendation")

   X.213.
        ITU, "OSI - Network Service Definition," ITU-T Recommendation
        X.213 (ISO/IEC 8072), ITU-T Telecommunication Standardization
        Sector of ITU, Geneva (November, 1995).  (Previously "CCITT
        Recommendation")

   NPI.
        UNIX. International, "Network Provider Interface Specification,"
        NPI Revision 2.0.0, UNIX International Publication, Parsippany,
        New Jersey (August 17, 1992).
        http://www.openss7.org/doc/npi.pdf

   X.214.
        ITU, "Transport Service Definitions for Open Systems
        Interconnection (OSI) for CCITT Applications," ITU-T
        Recommendation X.214 (ISO/IEC 8072), ITU-T Telecommunication
        Standardization Sector of ITU, Geneva (November, 1995).
        (Previously "CCITT Recommendation")

   X.219.
        ITU, "Information processing systems - Text Communication,
        Remote Operations: Model, Notation and Service Definition," ITU-
        T Recommendation X.219 (ISO/IEC 9072-1), ITU-T Telecommunication
        Standardization Sector of ITU, Geneva (n.d.).  (Previously
        "CCITT Recommendation")

   TPI.
        Open Group, "Transport Provider Interface Specification," TPI
        Version 2, Draft 2, Open Group Publication (1999).
        http://www.opengroup.org/onlinepubs/

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   ISO 8649.
        International Standards Organization, "Information Processing
        Systems - Open Systems Interconnection - Service Definition for
        the Association Control Service Element," ISO 8649:1988,
        International Standards Organization (1988).

   ISO 8650.
        International Standards Organization, "Information Processing
        Systems - Open Systems Interconnection - Protocol Specification
        for the Association Control Service Element," ISO 8650:1988,
        International Standards Organization (1988).

   XNS.
        Open Group, "Technical Standard: Network Services (XNS)," XNS
        Issue 5.2 Draft 2.0 (ISBN: 1-85912-241-8), Open Group
        Publication (1999).  http://www.opengroup.org/onlinepubs/

   RFC 2119.
        S. Bradner, "Key words for use in RFCs to Indicate Requirement
        Levels," RFC 2119 - BCP 14 (ISBN: 1-85912-241-8), Internet
        Engineering Task Force (March 1997).

Author's Addresses

   Brian Bidulock                                 Phone: +1-780-490-1141
   OpenSS7 Corporation                       Email: [email protected]
   1469 Jeffreys Crescent                    URL: http//www.openss7.org/
   Edmonton, AB  T6J 6T1
   Canada

   This draft expires March, 2003.

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                       List of Illustrations

   Figure 1 ASP and SGP both supporting Protocol Limits .........   11
   Figure 2 ASP and SGP both supporting Protocol Limits .........   12
   Figure 3 ASP and SGP both supporting Protocol Limits .........   13
   Figure 4 ASP and SGP both supporting Protocol Limits .........   14

                         Table of Contents

   Status of this Memo ..........................................    1
   Abstract .....................................................    1
   1 Introduction ...............................................    2
   1.1 Scope ....................................................    2
   1.2 Terminology ..............................................    2
   1.3 Overview .................................................    2
   1.3.1 Existing Information Management ........................    2
   1.3.2 SGINFO Information Management ..........................    3
   2 Conventions ................................................    3
   3 Protocol Elements ..........................................    3
   3.1 Parameters ...............................................    3
   3.1.1 Protocol Limits ........................................    3
   3.2 Messages .................................................    7
   3.2.1 ASP Active Acknowledgment (ASPAC ACK) ..................    7
   4 Procedures .................................................   10
   4.1 ASP Management Procedures ................................   10
   4.1.1 ASP Active Procedures ..................................   10
   4.2 Interworking .............................................   10
   5 Examples ...................................................   10
   5.1 ASP and SGP both supporting Protocol Limits ..............   11
   5.2 SGP only supporting Protocol Limits ......................   11
   5.2.1 ASP ignores Protocol Limits ............................   11
   5.2.2 ASP refuses Protocol Limits ............................   12
   5.3 ASP only supporting Protocol Limits ......................   13
   6 Security ...................................................   14
   7 IANA Considerations ........................................   14
   7.1 Protocol Extensions ......................................   14
   End Notes ....................................................   15
   References ...................................................   15
   Author's Addresses ...........................................   17
   List of Illustrations ........................................   18

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Copyright Statement

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