

          Software
          Product
          Description

          ________________________________________________________________

          PRODUCT NAME:  VAX Packetnet System Interface      SPD 25.40.15
                         (P.S.I.), Version 4.3

          DESCRIPTION

          The VAX Packetnet System Interface (VAX P.S.I.) product allows
          suitably configured VAX systems to connect to Packet Switch-
          ing Data Networks (PSDNs) conforming to CCITT recommendation
          X.25 (1978, 1980 or 1984) and/or to International Standards
          (ISO) 7776 and 8208. VAX P.S.I. allows a VAX system to function
          as Data Terminal Equipment (DTE) or Data Circuit Terminating
          Equipment (DCE) as follows:

          o  A packet-mode DTE connected to a supported PSDN

          o  A packet-mode DTE connected to a DCE conforming to ISO 7776
             and 8208

          o  A packet-mode DCE connected to a DTE conforming to ISO 7776
             and 8208

          o  A combination of the above modes chosen on a per-line basis

          In this SPD, descriptions referring to PSDNs also apply to sup-
          ported ISO point-to-point connections unless otherwise stated.

          VAX P.S.I. can be configured for either Native or Multi-host
          mode operation:

          o  VAX P.S.I. Native mode supports direct connections from a VAX
             system to one or more PSDNs, each of which may have one or
             more DTEs.

                                       DIGITAL                   July 1990

                                                               AE-L066P-TE

 


          VAX Packetnet System Interface                 SPD 25.40.15
          (P.S.I), Version 4.3  


          o  VAX P.S.I. Multi-host mode provides the features offered by
             VAX P.S.I. Native and also allows VAX P.S.I. Access systems
             to connect to a PSDN as though directly connected.

          Features

          VAX P.S.I. is a VMS layered product and can be used in the
          following ways:

          o  Process-to-process (X.25) communication

          o  Process-to-terminal (X.29) communication

          o  Terminal-to-Process (X.29) communication

          o  DECnet communications

          o  Open System Interconnection

          Process-to-process (X.25) Communication

          VAX P.S.I. supports access for VMS user programs written in VAX
          MACRO and high-level languages such as VAX FORTRAN. Programs
          executing in PDP-11 compatibility mode cannot use VAX P.S.I.

          The VAX P.S.I. programming interface allows application pro-
          grams to access the service interface to the packet level via
          the standard VMS QIO interface. Functions include the setting
          up and breaking of network connections, data transmission and
          reception, sending and receiving of interrupt messages, and re-
          setting of virtual circuits. The interface also allows splitting
          and recombining of messages which are longer than the packet
          size selected for the circuit.

          The programming interface enables an application program using
          VMS System Services to communicate with complementary software
          on other systems (Digital or non-Digital DTEs) accessible via
          the X.25 connection.

          Process-to-terminal and Terminal-to-process (X.29) Communica-
          tion

                                          2

 

          VAX Packetnet System Interface                 SPD 25.40.15
          (P.S.I), Version 4.3  



          VAX P.S.I. supports terminal communications according to CCITT
          recommendations X.3, X.28, and X.29 for:

          o  Outgoing terminal traffic

             VAX P.S.I. host users may make outgoing calls to other Digi-
             tal or non-Digital CPUs, or suitable network PADs accessible
             via a PSDN, using the X.29 programming interface or by using
             the host-based Packet Assembly/Disassembly (PAD) supplied
             with VAX P.S.I. The PAD facility accepts DCL-style commands
             or CCITT X.28 commands.

          o  Incoming terminal traffic

             The X.29 Interactive Terminal Interface allows remote asyn-
             chronous terminals (character-mode DTEs) connected to the
             network to communicate with the VAX P.S.I. host in a manner
             similar to local terminals. Dissimilarities may appear as a
             result of delays caused by the PSDN(s) and various PAD param-
             eter settings chosen by the user or peculiar to the PSDN(s).
             In this case, the remote PAD must perform code conversions
             between ASCII and the code the terminal uses. Note that there
             may be some restrictions imposed by the PSDN(s).

          Terminal parameters defined in the X.3 recommendation are ex-
          plicitly supported. Network-specific enhancements or extensions
          to the X.3 parameters are available at both the X.29 programming
          interface and the host-based PAD user interface. Terminal pro-
          cesses that depend on these extensions may cause problems when
          used on other PSDNs or when accessing one PSDN via another (for
          example, international access).

          The X.29 terminal interface is compatible with the local termi-
          nal interface except for the facilities where the PSDN does not
          provide adequate support. The X.29 interface includes support
          for specific X.29 signaling. For example, the break key can be
          used to disable output and the interrupt message can be mapped
          directly to the VMS interrupt character.

                                          3

 
          VAX Packetnet System Interface                 SPD 25.40.15
          (P.S.I), Version 4.3  



          The host-based PAD employs a DCL-style command syntax offering
          the ability to reference the CCITT PAD parameters symbolically,
          as well as an interface that conforms to the standard CCITT
          command signals. The host-based PAD also offers the capability
          of running multiple X.29 sessions using the VMS SPAWN and ATTACH
          commands. The host-based PAD supports reception of reselection
          messages to allow X.29 calls to be redirected to another DTE.

          The X.29 programming interface is similar to the X.25 program-
          ming interface and allows a VMS process to control the virtual
          circuit (for example, to modify PAD parameters or clear a call).
          The X.29 programming interface can also be used to make an out-
          going call to a remote PAD. The programming interface allows
          generation of PAD reselection messages.

          The maximum number of terminals supported (both local and remote
          X.29) must not exceed the number supported by VMS. The use of
          PVCs for X.29 connections is not defined by the 1980 and 1984
          CCITT recommendations, and is not available with VAX P.S.I.




          DECnet Communication

          VAX P.S.I. allows the use of DECnet-VAX facilities over X.25
          circuits. This technique is known as Data Link Mapping (DLM). A
          DECnet-VAX license is required to communicate with other DECnet
          nodes via a PSDN(s). For details, refer to DECnet-VAX Software
          Product Description (SPD 25.03.xx).

          Open System Interconnection

          VAX P.S.I. may be used for Open System Interconnection (OSI)
          communication using the OSI Applications Kernel product (OSAK).
          Refer to the VAX OSI Applications Kernel Software Product De-
          scription (SPD 27.47.xx).


                                          4

 
          VAX Packetnet System Interface                 SPD 25.40.15
          (P.S.I), Version 4.3  



          VAX P.S.I may be used with VAX FTAM for managing files on open
          systems (refer to VAX FTAM Software Product Description SPD
          29.86.xx), and with VAX Message Router X.400 Gateway to enable
          message exchange with other X.400 systems in X.400 public or
          private networks (refer to the VAX Message Router X.400 Software
          Product Description SPD 27.50.xx).

          VAX P.S.I. also provides features of X.25 which permit a Connec-
          tion Oriented Network Service (CONS) over X.25 according to ISO
          8348.

          Virtual Circuits

          VAX P.S.I. (in Native or Multi-host mode) supports both Per-
          manent Virtual Circuits (PVCs) and Switched Virtual Circuits
          (SVCs), and supports up to 512 virtual circuits in total per
          host machine. One virtual circuit is used for each:

          o  Incoming or outgoing X.29 terminal connection

          o  X.25 call using either a SVC or PVC

          o  Active Data Link Mapping (DLM) circuit

          Configuration

          VAX P.S.I. provides a configuration procedure to configure a VAX
          P.S.I. system locally. This allows network managers to create a
          configuration after initial installation or subsequently when
          reconfiguration is necessary.

          Network Management

          VMS provides a Network Control Program (NCP) for management
          of both DECnet-VAX and VAX P.S.I. This program allows network
          managers to define the line(s) and PSDN(s) to which the system
          is connected, select the mode (DTE or DCE) of each, specify
          destinations for incoming calls, access counters, and perform
          other maintenance functions.

                                          5

 
          VAX Packetnet System Interface                 SPD 25.40.15
          (P.S.I), Version 4.3  



          Problem Solving

          The TRACE utility assists problem solving by tracing and analyz-
          ing information at various stages as it passes between the PSDN
          and the VAX P.S.I. node. Event logging is available by means of
          normal VMS mechanisms.

          P.S.I. Accounting

          The P.S.I. Accounting utility enables the system manager to
          obtain information on VAX P.S.I. and network usage. The P.S.I.
          Accounting utility can extract the information collected and
          display the information directly on a terminal, or write the
          information to a file. Information can be extracted for selected
          records or a summary produced. The P.S.I. Accounting utility
          product is compatible with the VMS Accounting utility.

          In the case of incoming X.29 calls, no information can be stored
          relating to the process/account on which a user is logged; this
          may be obtained through correlation with VMS accounting records.

          P.S.I. Security

          The P.S.I. Security utility allows control of both remote DTE
          access to VAX P.S.I. and access to the PSDN(s) by VMS processes.
          The Security utility allows for access control on the basis of:

          o  The remote DTE numbers involved either on the basis of in-
             dividual DTE numbers or groups of DTE numbers with common
             leading digits.

          o  The process making the outgoing call or the application
             handling the incoming call.

          o  Whether or not the call is normally or reverse charged.

          In addition, when configured in Multi-host mode, VAX P.S.I. can
          apply security checks to both incoming calls to and outgoing
          calls from any suitably configured VAX P.S.I. Access node.
          Security on both the VAX P.S.I. and the VAX P.S.I. Access node
          is required for comprehensive protection.

                                          6

 
          VAX Packetnet System Interface                 SPD 25.40.15
          (P.S.I), Version 4.3  



          P.S.I. Mail

          The P.S.I. Mail utility allows communication across a PSDN via
          electronic mail between two VMS systems running VAX P.S.I. or
          VAX P.S.I. Access, using the VMS Mail facility even in the absence
          of any DECnet communications between the two DTEs. Refer to the 
          VMS Operating System Software Product Description (SPD 25.01.xx)
          for more information about VMS Mail.


          Conformance to Standards

          VAX P.S.I. conforms to the following standards:

          o  CCITT Recommendation X.25 (1978, 1980, or 1984) and ISO 8208
             and 7776 using the LAPB or LAPBE variants of the data link
             level and X.25 packet level protocols.

          o  ISO 3309 - Frame generation and recognition (not protocol)
             using High-Level Data Link Control (HDLC). Bisynchronous
             (BSC) framing is not supported.

          Table 1 (Optional Facility Support) describes the particular
          aspects of the CCITT X.25 recommendation supported by VAX P.S.I.
          Note that actual support for any given feature depends on the
          PSDN used.

          Line Interface

          The electrical line interface used for PSDN communications
          depends on the hardware device used. VAX P.S.I. provides only
          the electrical interface of a DTE rather than a DCE and does
          not provide clock signals. Therefore, an external clock source
          (e.g., a modem) is required.


                                          7

 

          VAX Packetnet System Interface                 SPD 25.40.15
          (P.S.I), Version 4.3  



          The range of supported devices cover V.24, V.35, V.10, RS232,
          RS422 and RS423 over point-to-point, 4-wire, synchronous, full-
          duplex lines at transmission rates up to 256K bits per second,
          as well as ISDN Basic Rate Access at transmission rates up to
          64K bits per second.

          Synchronous Communications Devices

          The communications devices supported by VAX P.S.I. are dif-
          ferent, particularly in the amount of CPUs used. For optimum
          performance, customers are recommended to use a DMA device. Re-
          fer to the VAX P.S.I. System Support Addendum (25.40.15-x) for
          details of the hardware configurations supported by VAX P.S.I.,
          supported line-speeds, and information about the supported syn-
          chronous driver products.

          Prerequisite Support

          For new PSDNs, the customer and Digital must jointly prepare
          a Network Profile and Customer Support Plan covering all the
          intended network nodes, their usage of SVCs, PVCs, and other
          network facilities, and their support. Without this Network
          Profile and Customer Support Plan, Digital cannot support the
          network connections.















                                          8

 




          INSTALLATION

          Digital requires that a customer's first purchase of this soft-
          ware product include Digital Installation Services. These ser-
          vices provide for installation of the software product by an
          experienced Digital Software Specialist.

          Only customers experienced with Digital's X.25 products should
          attempt second or subsequent installations. Digital recommends
          that all other customers purchase Digital's Installation Ser-
          vices.

          Customer Responsibilities

          In some cases, the PSDN supplier (or PTT) may impose restric-
          tions, limitations, or requirements on the proposed Digital
          network configuration. The customer must ensure that they under-
          stand and adhere to these controls for each and every network.

          Before installation of the software, the customer must:

          o  Previously have installed all required software and hardware
             including terminals.

          o  Obtain, install and demonstrate that any modems and other
             equipment and facilities necessary to interface to Digital's
             communication equipment are operational.

          o  Demonstrate equivalence of operation for modems other than
             Bell[TM] 208A, 208B, 209, 212A synchronous modems, or in
             Europe, PTT approved modems.

          o  Demonstrate that, where necessary, modems used meet the
             appropriate interface standards.

          o  Subscribe to the Open User Group and to at least two SVCs
             to complete the product's installation checkout (this tests
             loops information from the VAX P.S.I. system to the PSDN
             and back to VAX P.S.I. system). Systems that use PVCs or
             Closed User Groups only, or where the PSDN does not support
             calls to the same DTE address, require specially negotiated
             arrangements for Digital installation of the product.

                                          9

 

          VAX Packetnet System Interface                 SPD 25.40.15
          (P.S.I), Version 4.3  



          o  Make available, for a reasonable period of time, as mutually
             agreed by Digital and the customer, all hardware, communi-
             cation facilities and terminals that are to be used during
             installation.

          Delays caused by any failure to meet the responsibilities will
          be charged, at the then prevailing rate, for time and materials.

          Courtesy Installation Service

          This software product will be installed by Digital at no addi-
          tional charge if purchased concurrently with a Startup Service
          Package that includes installation service. This service may not
          be available in all countries.

          This service is available for those configurations which comply
          with the restrictions described under the SOFTWARE WARRANTY
          section. Consult the System Support Addendum (SSA 25.40.15-x)
          for a list of countries and networks where this service is
          available.

          HARDWARE REQUIREMENTS

          VAX, MicroVAX, VAXstation or VAXserver configuration as speci-
          fied in the System Support Addendum (SSA 25.40.15-x).

          SOFTWARE REQUIREMENTS *

          VMS Operating System

          For use with the synchronous communications interfaces, the
          appropriate device driver in the VAX Wide Area Network Device
          Drivers software is required. Refer to the VAX Wide Area Network
          Device Drivers Software Product Description SPD 29.64.xx.

          For use with the ISDN Basic Rate Access communications device,
          VAX ISDN software and hardware is required. Refer to the VAX
          ISDN Software Product Description SPD 31.23.xx.

          ORDERING INFORMATION

                                         10

 
          VAX Packetnet System Interface                 SPD 25.40.15
          (P.S.I), Version 4.3  



          Software Licenses: QL-071A*-**
          Software Media: QA-071A*-**
          Software Documentation: QA-071AA-GZ
          Software Product Services: QT-071A*-**

          *  Denotes variant fields. For additional information on avail-
             able licenses, services and media, refer to the appropriate
             price book.

          SOFTWARE LICENSING

          This software is furnished under the licensing provisions of
          Digital Equipment Corporation's Standard Terms and Conditions.
          For more information about Digital's licensing terms and poli-
          cies, please contact your local Digital office.

          LICENSE MANAGEMENT FACILITY

          This layered product supports the VMS License Management Facil-
          ity.

          License units for this product are allocated on a CPU-capacity
          basis.

          For more information on the License Management Facility, refer
          to the VMS Operating System Software Product Description (SPD
          25.01.xx) or the VMS Operating System documentation set.

          For more information about Digital's licensing terms and poli-
          cies, contact your local Digital office.









                                         11

 



          SOFTWARE PRODUCT SERVICES

          A variety of service options are available. For more informa-
          tion, please contact your local Digital office.

          SOFTWARE WARRANTY

          Warranty for this software product is provided by Digital with
          the purchase of a license for the product as defined in the
          Software Warranty Addendum of this SPD.

          Digital has designed or adapted this software product to operate
          with equipment conforming to ISO 7776/8208 with the public
          networks in the countries listed in the System Support Addendum
          (SSA 25.40.15-x), and with certain private PSDNs that have been
          approved by Digital.

          Optional Facility Support

          VAX P.S.I. support for any given CCITT X.25 facility depends on
          support for it in the appropriate supported PSDN. Generally, VAX
          P.S.I. is designed to disallow use of facilities that the PSDN
          will not support. Table 1 shows what VAX P.S.I. is capable of
          doing, rather than what it will do when used on any particular
          PSDN. The product documentation describes specific facility
          availability for the supported public PSDNs.

          Note: Not all optional facilities are supported for use with
          VAX P.S.I. Mail, DECnet Data Link Mapping (DLM) and VAX OSI
          Transport (VOTS).









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          VAX Packetnet System Interface                 SPD 25.40.15
          (P.S.I), Version 4.3  



          ________________________________________________________________

                                  Table 1: 
                         Optional Facility Support

                                                       Paragraph
                                                       Number
                                                       in CCITT X.25  VAX P.S.I.
          Number  Description of the Option              (1984)       Support

          1.      Extended packet sequence numbering     6.2             Yes

          2.      Non-standard default window size       6.10            Yes

          3.      Default throughput classes assign-     6.11            N/A
                  ment

          4.      Packet re-transmission                 6.4         See Note 1

          5.      Incoming calls barred                  6.5             N/A

          6.      Outgoing calls barred                  6.6             N/A

          7.      One-way logical channel outgoing       6.7             N/A

          8.      One-way logical channel incoming       6.8             Yes

          9.      Closed User Group                      6.14.1          Yes

          10.     CUG with outgoing access               6.14.2          Yes

          11.     CUG with incoming access               6.14.3          Yes

          12.     Incoming Calls barred within CUG       6.14.4          Yes

          13.     Outgoing Calls barred within CUG       6.14.5          Yes

          14.     CUG selection                          6.14.6          Yes


                                         13

 

          VAX Packetnet System Interface                 SPD 25.40.15
          (P.S.I), Version 4.3  

                              Table 1: (Cont.) 
                         Optional Facility Support


                                                       Paragraph
                                                       Number
                                                       in CCITT X.25  VAX P.S.I.
          Number  Description of the Option              (1984)       Support

          15.     CUG with outgoing access selection     6.14.7         No

          16.     Absence of both CUG selection          6.14.8         Yes
                  facilities

          17.     Bilateral CUG                          6.15.1         Yes

          18.     Bilateral CUG with outgoing access     6.15.2         Yes

          19.     Bilateral CUG selection                6.15.3         Yes

          20.     Reverse charging                       6.18           Yes

          21.     Reverse charging acceptance            6.19           Yes

          22.     Local charge prevention                6.20           N/A

          23.     Network User identification            6.21           Yes

          24.     Charging information                   6.22           Yes

          25.     RPOA selection                         6.23           Yes

          26.     Hunt group                             6.24        See Note 2

          27.     Call redirection                       6.25            N/A





                                         14

                              Table 1: (Cont.) 
                         Optional Facility Support

 
                                                       Paragraph
                                                       Number
                                                       in CCITT X.25  VAX P.S.I.
          Number  Description of the Option              (1984)       Support

          28.     Called line address modified noti-     6.26          Yes
                  fication

          29.     Call redirection notification          6.27          Yes

          30.     Transit delay selection and indi-      6.28          Yes
                  cation

          31.     On-line facility registration          6.1            No

          32.     Non-standard packet size               6.9            Yes

          33.     Flow control parameter negotiation     6.12           Yes

          34.     Throughput class negotiation           6.13           Yes

          35.     Fast select                            6.16           Yes

          36.     Fast select acceptance                 6.17           Yes

          37.     D-bit modification                     6.3            No

          38.     Abbreviated address                    -              N/A

          39.     Datagram queue length selection ex     -              No

          40.     Datagram service signal logical        -              No
                  channel



                                         15

                               Table 1: (Cont.) 
                         Optional Facility Support


                                                       Paragraph
                                                       Number
                                                       in CCITT X.25  VAX P.S.I.
          Number  Description of the Option              (1984)       Support

          41.     Datagram non-delivery indication       -              No

          42.     Datagram delivery confirmation         -              No

          43.     Call statistics (non-X.25)             -          See Note 3

          Notes:

          1.    This is not applicable to a DTE. VAX P.S.I. does not
                support receiving a level 3 Reject packet and will not
                generate one.

          2.    The individual DTEs must be assigned their own addresses
                independent of the hunt group address. VAX P.S.I. can then
                ignore the hunt group. Alternatively, each line on the
                same CPU can be configured as if connected to a separate
                PSDN; each with the same DTE address.

          3.    VAX P.S.I. does not generate these statistics, however,
                incoming statistics supplied by the PSDN are available in
                the accounting records and at the programming interface.

          4.    VAX P.S.I. does not support the following items of the
                CCITT X.25 recommendation:

                o  Multi-link protocol

                o  Use of the D-bit in outgoing packets



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          VAX Packetnet System Interface                 SPD 25.40.15
          (P.S.I), Version 4.3  





          [TM] Bell is a trademark of Bell Telephone Companies

          [R]  The DIGITAL Logo is a registered trademark of Digital
               Equipment Corporation.

          [TM] DECnet-VAX, VAX, MicroVAX, VAXstation, and VAXserver are
               trademarks of Digital Equipment Corporation.






























                                         17
