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draft-bidulock-sigtran-sginfo-02

Description: Request For Comments

You can download source copies of the file as follows:

draft-bidulock-sigtran-sginfo-02.txt in text format.
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Listed below is the contents of file draft-bidulock-sigtran-sginfo-02.txt.




Network Working Group                                     Brian Bidulock
INTERNET-DRAFT                                       OpenSS7 Corporation

Expires in six months                                    January 2, 2003

          Signalling Gateway (SG) Information (SGINFO) Support
                                  for
                   Signalling User Adaptation Layers
                 <draft-bidulock-sigtran-sginfo-02.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...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...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.  Change History

1.2.1.  Changes from Version 0.1 to Version 0.2

   - added this section,
   - updated references, release version and dates,
   - minor corrections,
   - updated postscript diagrams,
   - updated author's address.

1.3.  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...TUA] supporting ASP Management.

1.4.  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].

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     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.

1.4.1.  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 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 a 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.

1.4.2.  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]

B. Bidulock                    Version 0.2                        Page 3

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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.

     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 = 0x001b          |            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 0x001b
      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.

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    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 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 (0xFFFFFFFF).

    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
       (0xFFFFFFFF).

  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)

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       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.

    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 does 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.

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    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.

    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:

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      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 = 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 Tag Type 0x1 or 0x8                    /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x001b          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                        Protocol Limits                        /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0004          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                           Info String                         /

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    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      EDITOR'S NOTE:-  The parameter tag values shown as 0x001b
      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, ISUA, SUA
  and TUA 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 = 0x001b          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                        Protocol Limits                        /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0004          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                           Info String                         /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      EDITOR'S NOTE:-  The parameter tag values shown as 0x001b
      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.

     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.

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

4.  Procedures

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

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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
  Contexts (Interface Identifiers) 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

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.

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                      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

   (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.

     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.

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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

   (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.

   (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.

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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

   (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:

   (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.

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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

6.  Security

     SGINFO does not introduce any new security risks or considerations
  that are not already inherent in the UA [M2UA...TUA] Please see the
  "Security" sections of M2UA [M2UA], M3UA [M3UA], ISUA [ISUA], 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...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.

   (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 0x001b 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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End Notes

  [1]  See, for example, Section 1.2 of the specific UA document
       [M2UA...TUA].

  [2]  See, for example, Section 4 of the specific UA document
       [M2UA...TUA].

  [3]  See, for example, Section 3 of the specific UA document
       [M2UA...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).
       [Normative]

  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).
       [Normative]

  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.
       [Normative]

  ISUA.
       B. Bidulock, "SS7 ISUP-User Adaptation Layer (ISUA)," <draft-
       bidulock-sigtran-isua-00.txt>, Internet Engineering Task Force -
       Signalling Transport Working Group (January 5, 2003).  Work In
       Progress.  [Normative]

  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.  [Normative]

  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).  [Normative]

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  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).
       [Informative]

  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).
       [Informative]

  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).  [Informative]

  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).  [Informative]

  NPI.
       UNIX. International, "Network Provider Interface Specification,"
       NPI Revision 2.0.0, UNIX International Publication, Parsippany,
       New Jersey (August 17, 1992).  [Informative]

  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).
       [Informative]

  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.).  [Informative]

  TPI.
       Open Group, "Transport Provider Interface Specification," TPI
       Version 2, Draft 2, Open Group Publication (1999).  [Informative]

  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).  [Informative]

  ISO 8650.
       International Standards Organization, "Information Processing
       Systems - Open Systems Interconnection - Protocol Specification

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       for the Association Control Service Element," ISO 8650:1988,
       International Standards Organization (1988).  [Informative]

  XNS.
       Open Group, "Technical Standard: Network Services (XNS)," XNS
       Issue 5.2 Draft 2.0 (ISBN: 1-85912-241-8), Open Group Publication
       (1999).  [Informative]

  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).  [Normative]

Author's Addresses

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

  This draft expires July, 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 Change History ............................................    2
  1.2.1 Changes from Version 0.1 to Version 0.2 .................    2
  1.3 Terminology ...............................................    2
  1.4 Overview ..................................................    2
  1.4.1 Existing Information Management .........................    3
  1.4.2 SGINFO Information Management ...........................    3
  2 Conventions .................................................    3
  3 Protocol Elements ...........................................    3
  3.1 Parameters ................................................    4
  3.1.1 Protocol Limits .........................................    4
  3.2 Messages ..................................................    7
  3.2.1 ASP Active Acknowledgment (ASPAC ACK) ...................    7
  4 Procedures ..................................................    9
  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 ...............   10
  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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     This document and translations of it may be copied and furnished to
  others, and derivative works that comment on or otherwise explain it
  or assist in its implementation may be prepared, copied, published and
  distributed, in whole or in part, without restriction of any kind,
  provided that the above copyright notice and this paragraph are
  included on all such copies and derivative works.  However, this
  document itself may not be modified in any way, such as by removing
  the copyright notice or references to the Internet Society or other
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     The limited permission granted above are perpetual and will not be
  revoked by the Internet Society or its successors or assigns.

     This document and the information contained herein is provided on
  an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
  TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT
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  WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
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