sys/netproto/ipx/spx_timer.h

   1 /*
   2  * Copyright (c) 1995, Mike Mitchell
   3  * Copyright (c) 1982, 1986, 1988, 1993
   4  *      The Regents of the University of California.  All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  * 3. All advertising materials mentioning features or use of this software
  15  *    must display the following acknowledgement:
  16  *      This product includes software developed by the University of
  17  *      California, Berkeley and its contributors.
  18  * 4. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  *      @(#)spx_timer.h
  35  *
  36  * $FreeBSD: src/sys/netipx/spx_timer.h,v 1.10 1999/08/28 00:49:44 peter Exp $
  37  * $DragonFly: src/sys/netproto/ipx/spx_timer.h,v 1.2 2003/06/17 04:28:53 dillon Exp $
  38  */
  39
  40 #ifndef _NETIPX_SPX_TIMER_H_
  41 #define _NETIPX_SPX_TIMER_H_
  42
  43 /*
  44  * Definitions of the SPX timers.  These timers are counted
  45  * down PR_SLOWHZ times a second.
  46  */
  47 #define SPXT_REXMT      0               /* retransmit */
  48 #define SPXT_PERSIST    1               /* retransmit persistence */
  49 #define SPXT_KEEP       2               /* keep alive */
  50 #define SPXT_2MSL       3               /* 2*msl quiet time timer */
  51
  52 /*
  53  * The SPXT_REXMT timer is used to force retransmissions.
  54  * The SPX has the SPXT_REXMT timer set whenever segments
  55  * have been sent for which ACKs are expected but not yet
  56  * received.  If an ACK is received which advances tp->snd_una,
  57  * then the retransmit timer is cleared (if there are no more
  58  * outstanding segments) or reset to the base value (if there
  59  * are more ACKs expected).  Whenever the retransmit timer goes off,
  60  * we retransmit one unacknowledged segment, and do a backoff
  61  * on the retransmit timer.
  62  *
  63  * The SPXT_PERSIST timer is used to keep window size information
  64  * flowing even if the window goes shut.  If all previous transmissions
  65  * have been acknowledged (so that there are no retransmissions in progress),
  66  * and the window is too small to bother sending anything, then we start
  67  * the SPXT_PERSIST timer.  When it expires, if the window is nonzero,
  68  * we go to transmit state.  Otherwise, at intervals send a single byte
  69  * into the peer's window to force him to update our window information.
  70  * We do this at most as often as SPXT_PERSMIN time intervals,
  71  * but no more frequently than the current estimate of round-trip
  72  * packet time.  The SPXT_PERSIST timer is cleared whenever we receive
  73  * a window update from the peer.
  74  *
  75  * The SPXT_KEEP timer is used to keep connections alive.  If an
  76  * connection is idle (no segments received) for SPXTV_KEEP amount of time,
  77  * but not yet established, then we drop the connection.  If the connection
  78  * is established, then we force the peer to send us a segment by sending:
  79  *      <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK>
  80  * This segment is (deliberately) outside the window, and should elicit
  81  * an ack segment in response from the peer.  If, despite the SPXT_KEEP
  82  * initiated segments we cannot elicit a response from a peer in SPXT_MAXIDLE
  83  * amount of time, then we drop the connection.
  84  */
  85
  86 #define SPX_TTL         30              /* default time to live for SPX segs */
  87 /*
  88  * Time constants.
  89  */
  90 #define SPXTV_MSL       ( 15*PR_SLOWHZ)         /* max seg lifetime */
  91 #define SPXTV_SRTTBASE  0                       /* base roundtrip time;
  92                                                    if 0, no idea yet */
  93 #define SPXTV_SRTTDFLT  (  3*PR_SLOWHZ)         /* assumed RTT if no info */
  94
  95 #define SPXTV_PERSMIN   (  5*PR_SLOWHZ)         /* retransmit persistence */
  96 #define SPXTV_PERSMAX   ( 60*PR_SLOWHZ)         /* maximum persist interval */
  97
  98 #define SPXTV_KEEP      ( 75*PR_SLOWHZ)         /* keep alive - 75 secs */
  99 #define SPXTV_MAXIDLE   (  8*SPXTV_KEEP)        /* maximum allowable idle
 100                                                    time before drop conn */
 101
 102 #define SPXTV_MIN       (  1*PR_SLOWHZ)         /* minimum allowable value */
 103 #define SPXTV_REXMTMAX  ( 64*PR_SLOWHZ)         /* max allowable REXMT value */
 104
 105 #define SPX_LINGERTIME  120                     /* linger at most 2 minutes */
 106
 107 #define SPX_MAXRXTSHIFT 12                      /* maximum retransmits */
 108
 109 #ifdef  SPXTIMERS
 110 char *spxtimers[] =
 111     { "REXMT", "PERSIST", "KEEP", "2MSL" };
 112 #endif
 113
 114 /*
 115  * Force a time value to be in a certain range.
 116  */
 117 #define SPXT_RANGESET(tv, value, tvmin, tvmax) { \
 118         (tv) = (value); \
 119         if ((tv) < (tvmin)) \
 120                 (tv) = (tvmin); \
 121         else if ((tv) > (tvmax)) \
 122                 (tv) = (tvmax); \
 123 }
 124
 125 #endif /* !_NETIPX_SPX_TIMER_H_ */