Configuring and Managing Host-Based X.25 Links - Edition 5 (36939-90054)

16 Chapter1

Introduction

X.25 Network Connections

Many of the communications services available for HP 3000 Series 900

systems are provided through the Datacommunications and Terminal

Controller (DTC). There are six types of DTCs currently supported:

DTC 72MX, DTC 48, DTC 16, DTC 16iX, DTC 16MX and the DTC

16RX. The DTC 72MX, DTC 48 and the DTC 16 can support the

DTC/X.25 Network Access cards that make communications over

X.25 networks possible. The DTC 16iX, DTC 16MX and the DTC 16RX

do not support the DTC/X.25 Network Access cards.

The DTC 72MX allows up to three connector cards, plus a LAN card.

Up to three DTC/X.25 Network Access cards are supported. The

DTC 48 can contain up to six connector cards, up to three of which may

be DTC/X.25 Network Access cards. Slot 0 must contain an

asynchronous connector card, but slots 1 through 5 can contain any

combination of asynchronous cards and DTC/X.25 Network Access

cards. The DTC 16 can contain up to two asynchronous connector cards

and, optionally, a DTC/X.25 Network Access card as its third card.

NOTE

Throughout this manual, all DTCs supporting X.25 connections will be

referred to generically, unless their type is signiﬁcant to the topic under

discussion.

X.25 System-to-System Connections

Host-based X.25 system-to-system connections are supported through

the DTC/X.25 iX Network Link. This NS 3000/iX link makes it

possible for you to connect a HP 3000 Series 900 system to a public or

private X.25 packet switched network (PSN).

The DTC/X.25 iX Network Link requires that you have at least one

DTC/X.25 Network Access card installed in a DTC. You must also

purchase and install the X.25 iX System Access software on the

system.

Device Connections Via PAD

PAD support makes it possible for asynchronous serial devices, such as

terminals and serial printers, to be connected to the system through an

X.25 network. Serial devices are connected to a PAD, or Packet

Assembler/Disassembler. A PAD converts asynchronous character

streams into packets that can be transmitted over a packet switched

network. PAD packets follow the CCITT X.25 protocol

recommendations.