HP X.25/9000 Programmer's Guide

112 AppendixA

X.25 Packet Formats

Introduction

This appendix describes some of the packet formats speciﬁed in the

CCITT X.25 Recommendations. It also describes the X.25 actions

required to transmit the packet and the X.25 events that occur when the

packet is received. The packets described here are listed below:

• CALL REQUEST/INDICATION packet

• CALL ACCEPTED/CONNECTED packet

• CLEAR REQUEST/INDICATION packet

• DATA packet

• INTERRUPT packet

• INTERRUPT CONFIRMATION packet

• RESET REQUEST/INDICATION packet

• RESET CONFIRMATION packet

Although this appendix outlines how X.25 applications can access the

features deﬁned in the X.25 Recommendations, it does not describe the

use and range of possible values for packets and their ﬁelds. For

information about speciﬁc packet and ﬁeld values, refer to the CCITT

X.25 Recommendations.

Several packets are not accessible to X.25 applications. These packets

are listed below:

• DIAGNOSTIC packet

• REJ (retransmission) packet

• REGISTRATION packet

• REGISTRATION CONFIRMATION packet

• CLEAR CONFIRMATION packet

• RECEIVE READY packet

• RECEIVE NOT READY packet

X.25 level 3 handles these packets in accordance with the X.25

Recommendations without the need for any intervention by the user

application. X.25 does not support REGISTRATION packets.

36960-90061.bk Page 112 Friday, November 10, 2000 3:42 PM