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