HP 3000 Manuals

General Information Manual

Terminal-to-system communication 

On HP 3000 900 Series systems, terminal connectivity is provided by the
Datacommunications and Terminal Controller (DTC). The word terminal is
used in reference to the terminals, personal computers (in terminal
emulation mode), and serial printers that are connected to an HP 3000
system.

DTC 

The datacommunications and terminal controller (DTC) is a modular and
flexible LAN-based controller that provides location independent (for
example, for both local and remote using X.25) and Telnet protocols for
end-user access to HP and non-HP systems.  Users connected to the DTC
receive all the benefits associated with support of multivendor
standards, while at the same time having high-performance access to HP
3000 900 Series systems.

For access to a single HP 3000 900 Series systems, the DTC provides
simple and cost-effective connections to one predefined HP 3000 host,
that downloads and manages multiple DTCs.

As connectivity needs grow, the DTC can evolve into a powerful
multivendor communication server, providing integrated communications for
end-user access to multiple systems.  Through the use of an HP OpenView
PC-based workstation, a single operator can manage these DTC connections,
as well as other network and system elements, such as PADs and
switches--and soon hubs, bridges, and HP 3000 systems.  In addition, the
HP OpenView DTC Manager provides an intuitive and easy-to-use graphical
interface, leading to reduced cost of operation.  For more details on
X.25 communications on the DTC, please refer to the "Wide Area
Networking" section.  For more details on the Telnet access to the 900
Series, please refer to the "Multivendor system access" section.

HP 3000 900 Series system access 

Local access.   

The DTC provides local user access to one or more HP 3000 900 Series
systems.  The DTC supports data transfer at rates from 3,000 to 19,200
bps, with speed and parity sensing, full-duplex modems, spooled printers,
PCs in terminal-emulation mode, powerfail session recovery, type ahead,
and multisession capability.

The DTC attaches to the system using an industry-standard IEEE
802.3/Ethernet LAN. The DTC can attach to a ThinLAN, ThickLAN, or
EtherTwist cable at speeds of 10 Mbits per second.  In addition, the DTC
can be distributed throughout an extended LAN made up of LAN repeaters
and bridges.

Remote access.   

The DTC provides the same services to remote users, using the IEEE X.25
protocol or the ARPA Telnet protocol.  In X.25 environments, the DTC/XL
Network Link provides 900 Series access to remote users connected to an
asynchronous Packet Assembler/Disassembler (PAD) device.  In ARPA
environments, the HP Telnet Express gives remote Telnet users
high-performance 900 Series access over an internet IP Network.  In
addition, an HP ARPA Telnet Access card is available as an add-on for the
DTC48.


          Figure 5-2.  Location-Independent End-User Access 

Multivendor system access 

The DTC simultaneously supports the high-performance 900 Series protocol
and the ARPA Telnet protocol.  Consequently, local DTC users have
consistent access to HP 3000 900 Series systems and ARPA Telnet hosts,
that is, HP 9000 and Digital VAX systems with ARPA. In addition, a remote
user coming in over X.25 (using PAD) has the same system access
capabilities.


          Figure 5-3.  Consistent Access to HP 3000 900 Series, 
                       ARPA Telnet Host and Non-900 Series 
Extended switching also allows users connected to a DTC to access systems
using asynchronous connections.  The other system must be connected using
RS-232 connections to a second DTC on the same LAN. A single DTC can also
provide extended switching.

The DTC family 

There are two DTC models available for maximum flexibility in providing
terminal access to systems in a network:  the DTC16 and the DTC48.  The
DTC16 provides a cost-effective solution for entry-level HP 3000 systems,
and is well suited for those environments needing a small concentration
of ports.  The DTC16 provides up to 16 direct-connect ports or up to 12
modem-connect ports.  The DTC16 also offers an optional entry-level X.25
solution consisting of one X.25 RS-232 link.

The DTC48 provides a cost-effective solution for those environments
needing a larger configurations of ports.  The DTC48 provides up to 48
direct-connect ports or up to 36 modem-connect ports.  Like the DTC16,
the DTC48 supports X.25 connectivity.  The DTC48 supports up to three
X.25 network access cards providing either RS-232, RS-422, V.35, or V.36
connectivity.  In addition, the DTC48 supports one HP ARPA Telnet Access
card providing high-performance Telnet access from an ARPA system to an
HP 3000 900 Series.

An X.25 network access card and an ARPA Telnet access card can not reside
on the same DTC48.  For specific details, please see the HP 3000
Configuration Guide (5091-1731E) or the HP Networking Communications
Specification Guide (5091-1303E).

DTC Management 

HP offers two management solutions for downloading and managing DTCs:

   *   Simple management software based on the HP 3000 host for
       standalone system sites.  The PC-based management continues to
       provide additional benefits in this environment, in terms of
       ease-of-use for the network operator, thanks to the intuitive and
       easy-to-use graphical interface leading to reduced cost of
       operation.
   *   HP OpenView DTC Manager (PC-based) for multisystem (HP or
       multivendor) sites with multiple network equipment.  HP OpenView
       PC-based management provides an effective way to control network
       equipment from one workstation.  DTCs, PADs, and switches--and
       soon hubs, bridges, and HP 3000 systems--can be controlled from a
       single HP OpenView PC.

MPE/iX 5.0 Documentation