spx_timer.h revision 22975
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 * $Id$ 37 */ 38 39#ifndef _NETIPX_SPX_TIMER_H_ 40#define _NETIPX_SPX_TIMER_H_ 41 42/* 43 * Definitions of the SPX timers. These timers are counted 44 * down PR_SLOWHZ times a second. 45 */ 46#define SPXT_REXMT 0 /* retransmit */ 47#define SPXT_PERSIST 1 /* retransmit persistence */ 48#define SPXT_KEEP 2 /* keep alive */ 49#define SPXT_2MSL 3 /* 2*msl quiet time timer */ 50 51/* 52 * The SPXT_REXMT timer is used to force retransmissions. 53 * The SPX has the SPXT_REXMT timer set whenever segments 54 * have been sent for which ACKs are expected but not yet 55 * received. If an ACK is received which advances tp->snd_una, 56 * then the retransmit timer is cleared (if there are no more 57 * outstanding segments) or reset to the base value (if there 58 * are more ACKs expected). Whenever the retransmit timer goes off, 59 * we retransmit one unacknowledged segment, and do a backoff 60 * on the retransmit timer. 61 * 62 * The SPXT_PERSIST timer is used to keep window size information 63 * flowing even if the window goes shut. If all previous transmissions 64 * have been acknowledged (so that there are no retransmissions in progress), 65 * and the window is too small to bother sending anything, then we start 66 * the SPXT_PERSIST timer. When it expires, if the window is nonzero, 67 * we go to transmit state. Otherwise, at intervals send a single byte 68 * into the peer's window to force him to update our window information. 69 * We do this at most as often as SPXT_PERSMIN time intervals, 70 * but no more frequently than the current estimate of round-trip 71 * packet time. The SPXT_PERSIST timer is cleared whenever we receive 72 * a window update from the peer. 73 * 74 * The SPXT_KEEP timer is used to keep connections alive. If an 75 * connection is idle (no segments received) for SPXTV_KEEP amount of time, 76 * but not yet established, then we drop the connection. If the connection 77 * is established, then we force the peer to send us a segment by sending: 78 * <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK> 79 * This segment is (deliberately) outside the window, and should elicit 80 * an ack segment in response from the peer. If, despite the SPXT_KEEP 81 * initiated segments we cannot elicit a response from a peer in SPXT_MAXIDLE 82 * amount of time, then we drop the connection. 83 */ 84 85#define SPX_TTL 30 /* default time to live for SPX segs */ 86/* 87 * Time constants. 88 */ 89#define SPXTV_MSL ( 15*PR_SLOWHZ) /* max seg lifetime */ 90#define SPXTV_SRTTBASE 0 /* base roundtrip time; 91 if 0, no idea yet */ 92#define SPXTV_SRTTDFLT ( 3*PR_SLOWHZ) /* assumed RTT if no info */ 93 94#define SPXTV_PERSMIN ( 5*PR_SLOWHZ) /* retransmit persistence */ 95#define SPXTV_PERSMAX ( 60*PR_SLOWHZ) /* maximum persist interval */ 96 97#define SPXTV_KEEP ( 75*PR_SLOWHZ) /* keep alive - 75 secs */ 98#define SPXTV_MAXIDLE ( 8*SPXTV_KEEP) /* maximum allowable idle 99 time before drop conn */ 100 101#define SPXTV_MIN ( 1*PR_SLOWHZ) /* minimum allowable value */ 102#define SPXTV_REXMTMAX ( 64*PR_SLOWHZ) /* max allowable REXMT value */ 103 104#define SPX_LINGERTIME 120 /* linger at most 2 minutes */ 105 106#define SPX_MAXRXTSHIFT 12 /* maximum retransmits */ 107 108#ifdef SPXTIMERS 109char *spxtimers[] = 110 { "REXMT", "PERSIST", "KEEP", "2MSL" }; 111#endif 112 113/* 114 * Force a time value to be in a certain range. 115 */ 116#define SPXT_RANGESET(tv, value, tvmin, tvmax) { \ 117 (tv) = (value); \ 118 if ((tv) < (tvmin)) \ 119 (tv) = (tvmin); \ 120 else if ((tv) > (tvmax)) \ 121 (tv) = (tvmax); \ 122} 123 124#ifdef KERNEL 125extern int spx_backoff[]; 126#endif 127 128#endif 129