ACC HDLC/LAP-B (ABM) User's Guide

Overview
Modes of Operation
Chapter 1 15
Modes of Operation
As recommended by ITU-T, the BAC class of procedure involves two
combined stations operating in the Asynchronous Balanced Mode in
either two-way alternate or two-way simultaneous (half-duplex or
duplex) point-to-point configuration. Combined stations are
characterized by the ability to send both commands and responses,
receive both commands and responses, and provide for data link error
recovery.
The protocol optionally provides the ability to use extended sequence
numbering (modulus 128). Extended sequence numbering is selected by
configuration options. Normal operation uses modulus 8 sequence
numbering.
Data Rates
This protocol can be used at data rates up to 76.8k baud for 8-channel
ACC multiplexer cards. The HDLC LAP-B (ABM) Protocol product can
also be used at higher rates for high-speed ACC multiplexer cards, such
as the 8-Channel PCI.
Unformatted Frame or “Pass-through” Mode
This mode is no longer available with the HDLC/LAP-B product.
The “Level 1" protocol can be used to provide this functionality. Refer to
the Level 1- HDLC Framing Protocol User’s Guide for details.