/* $NetBSD: README.hdlc,v 1.7 2005/02/26 22:45:10 perry Exp $ */ /* * Copyright (c) University of British Columbia, 1984 * * @(#)README.hdlc 8.1 (Berkeley) 6/10/93 * * X.25 HDLC DATA LINK LEVEL: * * * This module implements the Link Level of the Open Systems Interconnect * Model. The implementation is based on the ISO High-Level Data Link * Control (HDLC). These procedures subscribe to the principles of the * ISO-Class of Procedures for point-to-point. These procedures implement * two-way asynchronous balanced mode (LAPB) as recommended by the CCITT. * * The HDLC protocol layer interface consists of the following procedures: * Hd_init (pr_init) * Hd_output (pr_output) * Hd_input (pr_input) * Hd_timer (pr_slowtimo) * * Note: Supervisory commands RR, RNR and REJ are not transmitted by this * station. * * This station never enters a busy (RNR) condition. * * The "Generate_rr" variable can be set to FALSE. This means that * we NEVER send an RR. This works just fine if the network level * is X.25 packet protocol -- which it is. * * Currently, this is only a DTE implementation. * * Think about: * If the remote is busy, no iframes are sent. The remote sends a RR * to clear this condition. However, this RR may be damaged, causing * a possible deadlock. A solution is to poll with iframe (P(S)==P(R) * of RNR) indefinitely. * * * Date: February 1984 * * Author: Gerald W. Neufeld * * Installation: Department of Computer Science * University of British Columbia * Vancouver, BC, CANADA. * * History: * * */