Nortel Networks Circuit Card - Manual (Page 901)

Page 901 of 906
Circuit Card Description and Installation
906
Appendix A: LAPB Data Link Control
protocol
Contents
This section contains information on the following topics:
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 901
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 901
Frame structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 902
LAPB balanced class of procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 903
Commands and responses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 904
Description of procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 905
Introduction
This chapter describes the LAPB Data Link Control protocol used with the
QPC513 ESDI card. The protocol is a subset of the HDLC procedures which
are described in International Organization for Standardization procedures
ISO 3309-1979 (E), ISO 4335-1979 (E) and appendices 1 and 2, and ISO
6256-1981 (E). Refer to these procedures for complete LAPB details.
Applications which use an ESDI port in synchronous mode must conform to
the following requirements.
Operation
Circuit Switch Equipment transfers data to the QPC513 in blocks consisting
of 1 to 128 eight-bit octets. Each block is processed in accordance with the