HP 3000 Manuals

COMMUNICATOR 3000/XL - REL. 2.0 (A.30.00)

Chapter 8  TECHNICAL ARTICLES 

DTC/Terminal Access 

by Rebecca Go Shih 
Business Networks Division 


The Datacommunications and Terminal Controller (DTC)/Terminal Access,
formerly known as the Distributed Terminal Controller, is a LAN based
communication server that provides asynchronous terminal and printer
connectivity to HP 3000 Series 900 systems.

For single system HP 3000 access, the DTC provides simple, cost-effective
asynchronous connections to one predefined host.  For multiple system
access and X.25 access, the DTC provides an integrated communications
server for both multisystem terminal access and X.25 communications.
Asynchronous and X.25 connections can be managed at a centralized site
using the OpenView DTC Manager (PN D2355A), which runs on the OpenView
Windows Workstation (PN32054A). Its OpenView Windows interface provides
an easy to use advanced graphical user interface to manage multiple DTCs.

Please refer to the "DTC/X.25 XL Network Link" Communicator article for
more information on the new DTC X.25 system to system and PAD features.

DTC/TERMINAL ACCESS LINK BENEFITS AND FEATURES 

Depending on the network management option chosen, a DTC may access a
single system or multiple systems.  If asynchronous access is required to
a single system, that system will download and manage the DTCs.  If
asynchronous access is required to multiple systems, the OpenView
Workstation will download and manage the DTCs.

When the DTC is managed by the HP 3000 Series 900, it provides these
benefits:

 *  Single system access, where DTC terminal access is defined for one HP
    3000 Series 900.

 *  High user availability, supported by powerfail session recovery.

 *  Ease of use for the end user; typeahead utility via a CI variable.

 *  Centralized DTC management from the host system.

When the DTC is managed by the OpenView DTC Manager Workstation, it
provides these benefits:

 *  Multiple system access; terminal users may switch between multiple HP
    3000 Series 900 systems to access distributed applications.

 *  High user availability, whereby:

      - Terminals can be added to the network without disrupting the
      Series 900 system availability.

      - Users have access to alternate systems in the event of a system
      failure.  If a system becomes unavailable, the user returns to the
      DTC interface and enters an alternate host name.

      - Powerfail session recovery (not supported on ports configured for
      multiple system access).

 *  Ease of use for the end user, provided by:

      - Automatic connection establishment to a predefined host.

      - User friendly DTC interface, from which the terminal user may
      switch systems by entering a host name.

      - Typeahead utility enabled by a CI variable.

 *  Ease of use for the network operator.

      - Easy to use graphical user interface, based on OpenView Windows
      for DTC management, providing better efficiency for network
      operators.

      - Reduced configuration necessary for terminals on the HP 3000
      Series 900 systems.

 *  Access security, where user logons can be restricted to one
    particular host.

An additional feature is the Workstation Configurator, which permits
users to create customized terminal and printer files, and to convert MPE
V/E terminal type files for use on MPE XL.

DTC/TERMINAL ACCESS PRODUCT ENHANCEMENTS 

DTC terminal I/O on MPE XL Release 2.0 includes the following
enhancements:  centralized PC based or individualized Host based network
management, terminal switching from a single DTC to one or more systems,
support of nailed and non-nailed devices, the OpenView DTC Manager, a CI
variable to enable typeahead, and the addition of the Workstation
Configurator on MPE XL. The following paragraphs describe these
enhancements in detail.

Host or PC Based Network Management 

DTC/Terminal Access now provides two network management options:  Host
based and PC based.  In the Host based environment, used for single
system access, an individual system continues to provide all
configuration, monitoring and diagnostic functions, as well as download
files for its configured DTCs.  The DTC continues to provide simple and
cost-effective asynchronous connections to a single host.

The PC based option is used for multiple systems access.  DTC management
can now be centralized at the OpenView DTC Manager workstation, rather
than at individual Series 900 hosts.  The OpenView DTC Manager allows the
user to configure, download, and control the DTCs configured for terminal
switching on the LAN. It uses the OpenView Windows user interface to
provide a user friendly, graphical way to depict the network map and to
design the configuration of each DTC managed by the workstation.

Terminal Switching 

Depending on the network management option selected, a DTC may be
configured to access a single system or to use DTC terminal switching
between multiple systems.  If single system access is desired, the DTC is
configured only through NMMGR so that each host performs the download and
management of its own DTCs, the same as in earlier releases.  If access
to multiple systems is required, then configuration must be performed on
both the host and the OpenView DTC Manager.  However, the OpenView DTC
Manager workstation will download and manage the DTCs on the LAN.

When multiple system access is used, users may access the DTC user
interface and request connection to one or more specified host names.  By
employing terminal switching between systems, users are able to access
different MPE XL systems without incurring the overhead associated with
Virtual Terminal (Network Services) sessions between systems.  In the
event of system down time, users may switch to an alternate system from
the DTC user interface.  Automatic connection to a default host may also
be specified on a port by port basis for each DTC.

In order to utilize terminal switching, the OpenView DTC Manager must be
used to configure the DTCs and the host names to be accessed by each DTC.
This PC based network management option is also required to support
non-nailed devices.

Nailed and Non-Nailed Devices 

Nailed devices are permanently assigned logical device numbers (ldevs)
when they are configured on an MPE XL system in NMMGR; connections to
nailed devices are always associated with these unique values.
Non-nailed devices can be configured in NMMGR but have no permanently
assigned ldev numbers.  Instead, ldev numbers are dynamically associated
with the device when the user requests a connection to the system.

The non-nailed device option permits a user at a device with a non-nailed
connection to logon, and have the system assign an ldev number from a
pool of available ldev numbers, which were defined during NMMGR
configuration.  When the user logs off, the assigned ldev is returned to
the pool and becomes available for use by another connection.

Employing non-nailed devices makes it possible to simplify the
configuration that must be done in NMMGR, and to add terminal users to
the network without having to reconfigure and reboot each host in order
to recognize the additional devices.  The nailed/non-nailed device
options are available only with PC based network management, although
they are configured on the XL host in NMMGR. Nailed devices are defined
using specific ldev numbers and device profiles (e.g., Ldev 100 is
assigned profile TR10D96 for a 9600 baud direct connection).  Non-nailed
devices are configured by entering a value for the total number of ldevs
in the non-nailed device pool for that particular system.

Printers and other serial devices accessed programmatically must be
configured as nailed devices, since only nailed devices can be
programmatically opened.

OpenView DTC Manager 

The OpenView DTC Manager is the application based on the OpenView Windows
Workstation which controls both the DTC/Terminal Access software and the
DTC/X.25 XL Network Link software.  For more details on X.25
communications on the DTC, please refer to the "DTC/X.25 XL Network Link"
Communicator article.

To operate the DTC/Terminal Access product, i.e., the DTCs on the
network, the OpenView DTC Manager performs the download of the
corresponding software and configuration files to the DTCs.  The OpenView
DTC Manager offers the following features:

 *  OpenView Windows user interface to present network map information in
    a graphical easy to read format.

 *  PC based network management functions to configure, control, monitor,
    and diagnose DTCs on the network.

 *  Diagnostic and status commands equivalent to that of the TermDSM
    utility on the XL host.

 *  Remote DTCs diagnostics and control via a serial modem dialup link
    whereby a local OpenView DTC Manager can access the DTCs managed by a
    remote OpenView DTC Manager.

 *  The OpenView DTC Manager is delivered on floppy discs for ease of
    installation and is loaded on the HP Vectra based OpenView Windows
    Workstation.

 *  The OpenView Windows Workstation is dedicated to running OpenView DTC
    Manager software.

Typeahead CI Variable 

MPE XL 2.0 now provides a CI variable for enabling and disabling the
typeahead facility; this replaces the command file TYPE.DTS0000.TELESUP
used in Release 1.2.

To enable the typeahead facility, the user enters the following command:

     :SETVAR HPTYPEAHEAD true

To disable the typeahead facility, the user enters:

     :SETVAR HPTYPEAHEAD false

Workstation Configurator 

The Workstation Configurator (TTUTIL XL) is a software tool that allows
users to create customized terminal and printer (TT) types, and to modify
port characteristics dynamically by changing their terminal type files.
This utility also permits the conversion of MPE V/E terminal type files
to MPE XL format.

The workstation configurator on MPE XL is different from the MPE V/E
version in the following ways:

 *  Users can go to the new conversion form, "Convert MPE/V Termtype,"
    from the main menu, and enter "X" to convert the termtype file.

 *  Several new messages were added:

      If the user selects an MPE V terminal type without selecting the
      conversion form (X), the error message "MPE/V termtype file; use
      Form X to convert to MPE/XL format" is displayed on the screen.

      If the user chooses an MPE XL terminal type and selects form (X),
      or if the user tries to convert an MPE XL terminal type, the error
      message "Termtype file is already in MPE/XL format" is returned.

      After the MPE V/E file has been converted to MPE XL format, the
      message "File converted to MPE/XL format" is displayed.

 *  The Stripped Characters and Modem Control screens are obsoleted.

 *  The Flow Control screen no longer requires the ENQ/ACK Protocol,
    Delay Protocol, or the Resume Read With XON After Echoed XOFF fields.

 *  The Control screen has obsoleted the Allow Escape Echo Control, Line
    Feed Accepted As Data, and Parity fields.  The three system responses
    to backspace for devices not supported on MPE XL were deleted as
    well.  A new field to enable typeahead was added.

 *  The Printer Control screen field for Status Requests Efficiency Mode
    is removed, since it is always enabled for MPE XL. The Wait Time For
    FOPEN Before Disconnect field was moved to this screen from the Modem
    Control menu.

 *  The Host based path in NMMGR allows only a default TT numbered file
    (see below) to be assigned to a device at configuration time.  The PC
    based path allows the assignment of either a default TT file or a
    uniquely created TT filename.

The Workstation Configurator is available independently of whether Host
based or PC based network management is selected.

MPE XL 2.0 supports default terminal types TT 10, 18, and 24, as well as
printer types TT 18, 21, 22, and 26.  TT 24 was added specifically for
use with MPE XL X.25 PAD terminals.  VFCPCL is the only default VFC file
on MPE XL. In addition, VFC files ported from MPE V/E need not be
converted on MPE XL.

To prepare a TT file, the user runs TTUTIL XL to create or convert the TT
file; or he may assign an existing TT filename to the NMMGR configuration
of a device so that it is automatically activated for that device when
the system is rebooted.  The user may then use the TT file in one of the
following ways:

      :HELLO user.logon;TERM=ttfilename

      or,

     :FILE outfile;DEV=6;ENV=TT##
     :FCOPY FROM=textfile;TO=*outfile

USER CAPABILITY AND MIGRATION 

In order to obtain the new terminal switching capability, the OpenView
DTC Manager workstation must be installed on the LAN, and the MPE XL FOS
updated to 2.0.  No new hardware enhancements are necessary for the DTC
to perform multiple system access / terminal switching.  A ROM upgrade to
the DTC may be necessary when adding the X.25 functionality to the DTC.
Please refer to the DTC/X.25 XL Network Link Communicator article for
more information.

Users who require access to only one system may install or update to the
Release 2.0 FOS without adding the OpenView DTC Manager functionality on
the LAN. They will retain the ability to configure and manage their DTCs
from the XL host via nailed devices.  These XL hosts and dedicated DTCs
will co-exist quite easily on the same LAN with the set of hosts and DTCs
that have been configured for the new 2.0 terminal switching features by
the OpenView DTC Manager.  Each set of XL systems and DTCs send out
network traffic on the LAN, but can communicate only with the devices for
which they have been configured.

The Workstation Configurator is included as part of the 2.0 FOS, and can
be run only by a user with OP (system supervisor) and PM (privileged
mode) capability.  It is used to create customized termtype files,
according to the needs of the user.  It is also used to convert existing
MPE V/E termtype files to MPE XL files.  These files will not be backward
compatible with MPE V/E, but will allow the user to carry over his device
specifications when he migrates from MPE V/E to MPE XL.

MPE/iX Communicators