1: /*
   2:  * Copyright (c) 1982, 1986, 1988 Regents of the University of California.
   3:  * All rights reserved.
   4:  *
   5:  * Redistribution and use in source and binary forms are permitted
   6:  * provided that this notice is preserved and that due credit is given
   7:  * to the University of California at Berkeley. The name of the University
   8:  * may not be used to endorse or promote products derived from this
   9:  * software without specific prior written permission. This software
  10:  * is provided ``as is'' without express or implied warranty.
  11:  *
  12:  *	@(#)spp_timer.h	7.1 (Berkeley) 3/12/88
  13:  */
  14: 
  15: /*
  16:  * Definitions of the SPP timers.  These timers are counted
  17:  * down PR_SLOWHZ times a second.
  18:  */
  19: #define SPPT_NTIMERS    4
  20: 
  21: #define SPPT_REXMT  0       /* retransmit */
  22: #define SPPT_PERSIST    1       /* retransmit persistance */
  23: #define SPPT_KEEP   2       /* keep alive */
  24: #define SPPT_2MSL   3       /* 2*msl quiet time timer */
  25: 
  26: /*
  27:  * The SPPT_REXMT timer is used to force retransmissions.
  28:  * The SPP has the SPPT_REXMT timer set whenever segments
  29:  * have been sent for which ACKs are expected but not yet
  30:  * received.  If an ACK is received which advances tp->snd_una,
  31:  * then the retransmit timer is cleared (if there are no more
  32:  * outstanding segments) or reset to the base value (if there
  33:  * are more ACKs expected).  Whenever the retransmit timer goes off,
  34:  * we retransmit one unacknowledged segment, and do a backoff
  35:  * on the retransmit timer.
  36:  *
  37:  * The SPPT_PERSIST timer is used to keep window size information
  38:  * flowing even if the window goes shut.  If all previous transmissions
  39:  * have been acknowledged (so that there are no retransmissions in progress),
  40:  * and the window is too small to bother sending anything, then we start
  41:  * the SPPT_PERSIST timer.  When it expires, if the window is nonzero,
  42:  * we go to transmit state.  Otherwise, at intervals send a single byte
  43:  * into the peer's window to force him to update our window information.
  44:  * We do this at most as often as SPPT_PERSMIN time intervals,
  45:  * but no more frequently than the current estimate of round-trip
  46:  * packet time.  The SPPT_PERSIST timer is cleared whenever we receive
  47:  * a window update from the peer.
  48:  *
  49:  * The SPPT_KEEP timer is used to keep connections alive.  If an
  50:  * connection is idle (no segments received) for SPPTV_KEEP amount of time,
  51:  * but not yet established, then we drop the connection.  If the connection
  52:  * is established, then we force the peer to send us a segment by sending:
  53:  *	<SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK>
  54:  * This segment is (deliberately) outside the window, and should elicit
  55:  * an ack segment in response from the peer.  If, despite the SPPT_KEEP
  56:  * initiated segments we cannot elicit a response from a peer in SPPT_MAXIDLE
  57:  * amount of time, then we drop the connection.
  58:  */
  59: 
  60: #define SPP_TTL     30      /* default time to live for SPP segs */
  61: /*
  62:  * Time constants.
  63:  */
  64: #define SPPTV_MSL   ( 15*PR_SLOWHZ)     /* max seg lifetime */
  65: #define SPPTV_SRTTBASE  0           /* base roundtrip time;
  66: 						   if 0, no idea yet */
  67: #define SPPTV_SRTTDFLT  (  3*PR_SLOWHZ)     /* assumed RTT if no info */
  68: 
  69: #define SPPTV_PERSMIN   (  5*PR_SLOWHZ)     /* retransmit persistance */
  70: #define SPPTV_PERSMAX   ( 60*PR_SLOWHZ)     /* maximum persist interval */
  71: 
  72: #define SPPTV_KEEP  ( 75*PR_SLOWHZ)     /* keep alive - 75 secs */
  73: #define SPPTV_MAXIDLE   (  8*SPPTV_KEEP)    /* maximum allowable idle
  74: 						   time before drop conn */
  75: 
  76: #define SPPTV_MIN   (  1*PR_SLOWHZ)     /* minimum allowable value */
  77: #define SPPTV_REXMTMAX  ( 64*PR_SLOWHZ)     /* max allowable REXMT value */
  78: 
  79: #define SPP_LINGERTIME  120         /* linger at most 2 minutes */
  80: 
  81: #define SPP_MAXRXTSHIFT 12          /* maximum retransmits */
  82: 
  83: #ifdef  SPPTIMERS
  84: char *spptimers[] =
  85:     { "REXMT", "PERSIST", "KEEP", "2MSL" };
  86: #endif
  87: 
  88: /*
  89:  * Force a time value to be in a certain range.
  90:  */
  91: #define SPPT_RANGESET(tv, value, tvmin, tvmax) { \
  92:     (tv) = (value); \
  93:     if ((tv) < (tvmin)) \
  94:         (tv) = (tvmin); \
  95:     else if ((tv) > (tvmax)) \
  96:         (tv) = (tvmax); \
  97: }
  98: 
  99: #ifdef SUPERVISOR
 100: extern int spp_backoff[];
 101: #endif

Defined variables

spptimers defined in line 84; used 2 times

Defined macros

SPPTV_KEEP defined in line 72; used 7 times
SPPTV_MAXIDLE defined in line 73; used 1 times
SPPTV_MIN defined in line 76; used 4 times
SPPTV_MSL defined in line 64; never used
SPPTV_PERSMAX defined in line 70; used 1 times
SPPTV_PERSMIN defined in line 69; used 1 times
SPPTV_REXMTMAX defined in line 77; used 4 times
SPPTV_SRTTBASE defined in line 65; used 2 times
SPPTV_SRTTDFLT defined in line 67; used 2 times
SPPT_2MSL defined in line 24; never used
SPPT_KEEP defined in line 23; used 6 times
SPPT_NTIMERS defined in line 19; used 1 times
SPPT_PERSIST defined in line 22; used 9 times
SPPT_RANGESET defined in line 91; used 5 times
SPPT_REXMT defined in line 21; used 14 times
SPP_LINGERTIME defined in line 79; never used
SPP_MAXRXTSHIFT defined in line 81; used 5 times
SPP_TTL defined in line 60; never used

Usage of this include

Last modified: 1988-04-28
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