IBM X.25 NPSI V3R9 -- Currency Support

Software Announcement
September 22, 1998
Announcement Letter Number: 298-336

Table of Contents:

At a Glance

New for V3R9:

  • Concurrent support for ACF/NCP V7R7

  • New generation support using the IBM High Level Assembler

  • New Flow Control Mechanism for X.25 APPN Inbound Traffic

  • Improved Session Management for PVC LLC0 PCNE Sessions

  • New use of the LLC4 GATE Error/Information Report

  • Enhanced Flow Control for FTPI (GATE) Connections
For ordering, contact:
  Your IBM representative, an IBM
  Business Partner, or IBM North America
  Sales Centers at
    800-IBM-CALL  Reference: LE010


New X.25 Network Control Program Packet Switching Interface (NPSI) continues to:

  • Protect your investment in the 3745 Communications Controller.

  • Maintain the quality and dependability of this critical network component.
New for V3R9:
  • Concurrent support for ACF/NCP V7R7.

  • New X.25 NPSI support for the new High Level Assembler (5696-234) requirements implemented in ACF/SSP V4R7.

    Refer to the Description and Software Requirements sections. Also, read the ACF/SSP V4R7 Software Announcement 298-334 dated September 22, 1998.

  • New flow control mechanism for X.25 APPN (R) inbound traffic improves management of traffic flow between host and downstream sessions.

  • X.25 NPSI improves session management on Permanent Virtual Circuit (PVC) LLC0 sessions by providing the downstream devices the status of the LU session between NPSI and the host application.

  • The LLC4 GATE Error/Information Report allows the network manager to control whether or not an invalid GATE (General Access to X.25 Transport Extension) command should take down the LU session between NPSI and the host GATE application.

  • Enhanced flow control for Fast Transaction Processing Interface (FTPI) GATE connections by monitoring outbound traffic congestion and disconnecting the session if appropriate.

Intended Customers

  • Customers running X.25 NPSI V1 through V3 migrating to ACF/NCP V7R7

  • Customers with 3745 and 3746 Model 900 Communications Controllers

Key Prerequisites

  • IBM ACF/NCP V7R7 for OS/390 (R) (MVS/ESA (TM)), VM/ESA (R), VSE/ESA (5648-063)

  • IBM ACF/SSP V4R7 for OS/390 (MVS/ESA) (5655-041)

  • IBM ACF/SSP V4R7 for VM/ESA (5654-009)

  • IBM ACF/SSP V4R7 for VSE/ESA (5686-064)

Planned Availability Date

  • September 25, 1998, for OS/390 (MVS/ESA)

  • October 30, 1998, for VM/ESA and VSE/ESA


This announcement is provided for your information only. For additional information, contact your IBM representative, call 800-IBM-4YOU, or visit the IBM home page at:


Currency for ACF/NCP V7R7

In addition to the changes listed below, X.25 NPSI allows concurrent operation with ACF/NCP V7R7 and ACF/SSP V4R7.

New NCP Generation Assembler Support

Starting with X.25 NPSI V3R9, important changes have been made to the X.25 NPSI generation assembler support.

Beginning with ACF/SSP V4R7, the Network Definition Facility (NDF) requires the corequisite support of the IBM High Level Assembler (HLAS) program product (5696-234). You will now be required to use the HLAS for generating X.25 NPSI load modules.

Prior to ACF/SSP V4R7, two different assemblers (IFZ assembler for VSE and IHR90 assembler for MVS (TM) and VM) were shipped with ACF/SSP. These two assemblers (IFZ and IHR90) will continued to be shipped with ACF/SSP V4R7 to support load module generations on X.25 NPSI releases prior to V3R9.

IBM's HLAS program product provides increased generation reliability for growing network definitions in addition to service support into the Year 2000.

Refer to the ACF/SSP V4R7 Software Announcement 298-334 (RFA30840), dated September 22, 1998, for details of this new support and information on prerequisites.

X.25 APPN Inbound Data Flow Control

NPSI now monitors inbound PIU accumulation to detect a simulated Virtual Route (VR) Held condition and transmits an outbound Receiver Not Ready (RNR) packet during this condition, pausing the exchange of data traffic. After the conditions clear, NPSI responds by transmitting a Receiver Ready packet to restart the exchange of data. This new enhancement provides improved flow control over end-to-end X.25 lines reducing congestion conditions caused by intermittent line outages.

New LLC0 (GATE) PVC Reset Support

This new release of NPSI offers additional PVC Reset packet support. A new keyword (RESETUNB=YES) causes NPSI to transmit a RESET packet on a Logical Link Control (LLC0) when a BIND or UNBIND event occurs on the session between VTAM (R) and NPSI, disconnecting the session.

Sending a reset packet to a downstream terminal when the NPSI host session is disconnected and then reconnected prevents the downstream terminal from flooding the network with packets that could congest traffic and increase network line costs.

New Use of LLC4 (GATE) Error/Information Report

NPSI is prevented from transmitting a negative sense response to the host Communications Transport Control Program (CTCP) application by sending a GATE Error/Information Report

The network managers can manage and prevent unnecessary outages on NPSI sessions.

Enhanced Flow Control for FTPI (GATE) Connections

Two new keywords (FTPITH and FTPITHTO) on the X25.MCH statement allow you to reset an FTPI GATE virtual circuit when outbound traffic threshold limits are exceeded.

You can determine the amount of downstream congestion in the network and then disconnect the session to prevent unnecessary retransmission of data.

Year 2000

This product is Year 2000 ready. When used in accordance with its associated documentation, it is capable of correctly processing, providing, and/or receiving date data within and between the twentieth and twenty-first centuries, provided all other products (for example, software, hardware, and firmware) used with the product properly exchange accurate date data with it.


SmoothStart (TM)/Installation Services

IBM Installation Services or Installation Services are not provided for X.25 NPSI.

Your country may offer NCP installation and customization through fee-based Country Specific Offerings. Contact IBM for further information on what is available in your country.

If you migrate to APPN, IBM can provide APPN Migration Services. These flexible services are designed around your specific migration. Our project management team helps ensure that all the pieces of your network fall into place when migration is finished. Details are on the Web:


Software Announcements dated September 22, 1998:

      MVS/ESA, MVS, and SmoothStart are trademarks of International
      Business Machines Corporation in the United States or other
      countries or both.
      APPN, OS/390, VM/ESA, and VTAM are registered trademarks of
      International Business Machines Corporation in the United
      States or other countries or both.
      Other company, product, and service names may be trademarks or
      service marks of others.



X.25 NPSI Version 3 supports attachment of the 3745 and 3746 Model 900 Communication Controller to X.25 data transmission services that comply with CCITT Recommendation X.25 (Melbourne 1988, Malag-Torremolinos 1984, or Geneva 1980). X.25 NPSI also complies with International Organization for Standardization (ISO) standards 7776 and 8208.


Specified Operating Environment

Hardware Requirements

  • X.25 NPSI V3R9 runs concurrently on the 3745 Communication Controller

  • Microcode engineering change level D22512, or higher, is required to support the 3746 Model 900 using X.25 protocol on communication lines with X.25 NPSI V3R8, or later, control.
Software Requirements
  • X.25 NPSI V3R9 runs concurrently with ACF/NCP V7R7 (5648-063)

  • X.25 NPSI V3R9 is generated using the following ACF/SSP programs:
    • ACF/SSP V4R7 for OS/390 (R) (MVS/ESA (TM)) (5655-041)

    • ACF/SSP V4R7 for VM/ESA (R) (5654-009)

    • ACF/SSP V4R7 for VSE/ESA (5686-064)
If the HLAS does not come installed on your operating system, you need to order it. The following table can help you determine if the High Level Assembler is integrated with your operating system.
                                           High Level
                              Program      Assembler
Operating System              Number       V1R2 (5696-234)

MVS/ESA V5R1 5655-068, Order separately and later 5655-069 VSE/ESA V1R4.3 5750-ACD Order separately and V1R4.4 VM/ESA V2R2 5654-030 Order separately and V2R3 OS/390 R1, R2, R3 5645-001 Integrated OS/390 R4, R5 5647-A01 Integrated VSE/ESA V2R2 5690-VSE Integrated and V2R3

In addition to the High Level Assembler requirements the following APARs are required:

  • DFSMS/MVS (R) OW26738 for the binder
  • DFSMS/MVS OW27802 for the linkage editor
  • VM/ESA VM61534 for the linkage editor
In addition to providing the generation function for this release, ACF/SSP provides utilities for loading, dumping, and trace formatting for X.25 NPSI when used with these operating systems.

Compatibility: X.25 NPSI V3R9 operates concurrently with ACF/NCP V7R7. Refer to the Hardware Requirements, Software Requirements, and Compatibility sections of ACF/NCP Software Announcement 298-332 for additional operating system dependencies.

The following NetView (R) Performance Monitor APARs are required for compatibility with V3R9 operating on 3746 Model 900 lines.

  • Version 2 Release 1 MVS (TM) -- OW10583
  • Version 2 Release 2 MVS -- OW10583
X.25 NPSI V3R9 is compatible with the 1988 and 1984 version of the CCITT X.25 recommendation, as defined in The X.25 1984/1988 Interface For Attaching IBM SNA Nodes To Packet Switched Data Networks General Information (GA27-3761). X.25 NPSI V3R9 remains compatible with the 1980 version of the CCITT X.25 recommendation, as defined in The X.25 Interface For Attaching IBM SNA Nodes to Packet Switched Data Networks General Information (GA27-3345). X.25 NPSI V3R9 is intended to attach to packet-switched networks conforming to these recommendations.

X.25 NPSI V3R9 connection to a private network or direct X.25 device connection to NPSI is supported if these connections conform to the above CCITT recommendations. Service support for these connections will be under the terms of the Multiple Supplier Systems Bulletin (G120-6648). The licensee is responsible for verifying conformance, and for understanding the limitations of these connections.

If the network supplier requires certification of network connection, the customer or network supplier is responsible for obtaining the necessary certification.

Performance Considerations: Performance levels will vary, depending on the machine and configuration in which the program is operating. IBM aids, such as the 3745 Configurator, should be used to assess performance capabilities and storage estimates. Attaching X.25 lines to the 3746 Model 900 provides increased configuration flexibility while providing current 3745 performance results. There are no significant performance improvements on X.25 3746 Model 900 lines.

Planning Information

Customer Responsibilities: X.25 NPSI V3R9 will replace X.25 NPSI V3R8 on the following dates:

  • X.25 NPSI for OS/390 (MVS/ESA) -- September 25, 1998

  • X.25 NPSI for VM/ESA and VSE/ESA -- October 30, 1998
X.25 NPSI V3R9 will be shipped from IBM Software Manufacturing Solutions (SMS) after availability.

To install and use X.25 NPSI V3R9:

  • Ensure that the X.25 network conforms to CCITT Recommendation X.25 (Melbourne 1988, Malaga-Torremolinos 1984, or Geneva 1980).

  • Obtain necessary certification if the supplier requires network connection certification. Contact your IBM representative to determine specific network support.

  • Provide at least the minimum machine and programming environments in which X.25 NPSI V3R9 will operate.
Packaging: X.25 NPSI V3R9 will be shipped on a 6250 BPI magnetic tape reel, on a 3480 cartridge, or on a 4-mm DAT tape.

Security, Auditability, and Control

If sensitive data is sent over external communications facilities, user management may wish to pursue the application of cryptography. The customer is responsible for evaluation, selection, and implementation of security features, administrative procedures, and appropriate controls in application systems and communication facilities.


Current Licensees

Current licensees of X.25 NPSI for OS/390 (MVS/ESA), VM/ESA, and VSE/ESA (5688-035) will be sent a program reorder form that may be returned directly to IBM SMS.

Reorder forms are scheduled to be mailed by:

  • October 9, 1998, for IBM X.25 NPSI for OS/390 (MVS/ESA)

  • November 13 1998, for IBM X.25 NPSI for VM/ESA and VSE/ESA
Reorder forms returned to SMS will be processed within 10 work days of receipt.

New Licensees

Orders for new licenses will be accepted now.

For ordering information on the base program, X.25 V3R9, refer to Software Announcement 296-040 dated February 27, 1996.

Shipment will begin on the planned availability date. Orders that ship:

  • Before the planned availability date will receive X.25 NPSI V3R8.

  • After the planned availability date will receive X.25 NPSI V3R9.
New users of X.25 NPSI V3R9 should specify:
               Type             Model

5688 035


Terms and conditions announced in Software Announcement 293-637 dated October 28, 1993, are unaffected by this announcement.

Support Line: S/390 (R)


The charges provided in this announcement are suggested retail prices for the U.S. only and are provided for your information only. Dealer prices may vary, and prices may also vary by country. Prices are subject to change without notice. For additional information and current prices, contact your local IBM representative.

Charges are unaffected by this announcement.

One-Time Charge (OTC): Customers who pay an OTC for a licensed program receive enhancements and future releases, if any, at no additional charge. Significant new function may be offered as an optional feature and charged for separately. If a replacement program is announced and the customer elects to license the replacement program, a time-based upgrade credit may apply.

Usage Charge: Charges for this program are based on usage levels. When a customer upgrades to a higher level of usage, a usage upgrade charge will apply, equal to the difference between the charge for the current level of usage and the higher level of usage.


To order, contact the IBM North America Sales Centers, your local IBM representative, or your IBM Business Partner.

IBM North America Sales Centers, our national direct marketing organization, can add your name to the mailing list for catalogs of IBM products.

 Phone:     800-IBM-CALL
 Fax:       800-2IBM-FAX
 Mail:      IBM North America Sales Centers
            Dept. LE010
            P.O. Box 2690
            Atlanta, GA  30301-2690
 Reference: LE010

To identify your local IBM Business Partner or IBM representative, call 800-IBM-4YOU.

Note: Shipments will begin after the planned availability date.


      MVS/ESA and MVS are trademarks of International Business
      Machines Corporation in the United States or other countries or
      OS/390, VM/ESA, DFSMS/MVS, NetView, and S/390 are registered
      trademarks of International Business Machines Corporation in
      the United States or other countries or both.
      Other company, product, and service names may be trademarks or
      service marks of others.

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