[unix-history] / usr / src / sys / netccitt / README.hdlc

/*
 * Copyright (c) University of British Columbia, 1984
 *                                                                          
 * @(#)README.hdlc	8.1 (Berkeley) %G%
 *
 *  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 recommented by the CCITT.
 *
 *  The HDLC protocol layer interface consists of the following procedures:
 *    Hd_init       (pr_init) 
 *    Hd_ouput      (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) indefinitly.
 *
 *
 *  Date:             February 1984
 *
 *  Author:           Gerald W. Neufeld
 *                     
 *  Installation:     Department of Computer Science
 *                    University of British Columbia
 *                    Vancouver, BC, CANADA.
 *
 *  History:
 *  
 *                                                                      
 */
Commit	Line	Data
cae6e6da KB	1	/*
	2	* Copyright (c) University of British Columbia, 1984
	3	*
40c85c95	4	* @(#)README.hdlc 8.1 (Berkeley) %G%
cae6e6da KB	5	*
	6	* X.25 HDLC DATA LINK LEVEL:
	7	*
	8	*
	9	* This module implements the Link Level of the Open Systems Interconnect
	10	* Model. The implementation is based on the ISO High-Level Data Link
	11	* Control (HDLC). These procedures subscribe to the principles of the
	12	* ISO-Class of Procedures for point-to-point. These procedures implement
	13	* two-way asynchronous balanced mode (LAPB) as recommented by the CCITT.
	14	*
	15	* The HDLC protocol layer interface consists of the following procedures:
	16	* Hd_init (pr_init)
	17	* Hd_ouput (pr_output)
	18	* Hd_input (pr_input)
	19	* Hd_timer (pr_slowtimo)
	20	*
	21	* Note: Supervisory commands RR, RNR and REJ are not transmitted by this
	22	* station.
	23	*
	24	* This station never enters a busy (RNR) condition.
	25	*
	26	* The "Generate_rr" variable can be set to FALSE. This means that
	27	* we NEVER send an RR. This works just fine if the network level
	28	* is X.25 packet protocol -- which it is.
	29	*
	30	* Currently, this is only a DTE implementation.
	31	*
	32	* Think about:
	33	* If the remote is busy, no iframes are sent. The remote sends a RR
	34	* to clear this condition. However, this RR may be damaged, causing
	35	* a possible deadlock. A solution is to poll with iframe (P(S)==P(R)
	36	* of RNR) indefinitly.
	37	*
	38	*
	39	* Date: February 1984
	40	*
	41	* Author: Gerald W. Neufeld
	42	*
	43	* Installation: Department of Computer Science
	44	* University of British Columbia
	45	* Vancouver, BC, CANADA.
	46	*
	47	* History:
	48	*
	49	*
	50	*/