1 /* 2 * Copyright (c) 1982, 1986, 1988, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)spp_timer.h 8.1 (Berkeley) 6/10/93 34 * $FreeBSD: src/sys/netns/spp_timer.h,v 1.9 1999/12/29 04:46:20 peter Exp $ 35 */ 36 37 #ifndef _NETNS_SPP_TIMER_H_ 38 #define _NETNS_SPP_TIMER_H_ 39 40 /* 41 * Definitions of the SPP timers. These timers are counted 42 * down PR_SLOWHZ times a second. 43 */ 44 #define SPPT_NTIMERS 4 45 46 #define SPPT_REXMT 0 /* retransmit */ 47 #define SPPT_PERSIST 1 /* retransmit persistance */ 48 #define SPPT_KEEP 2 /* keep alive */ 49 #define SPPT_2MSL 3 /* 2*msl quiet time timer */ 50 51 /* 52 * The SPPT_REXMT timer is used to force retransmissions. 53 * The SPP has the SPPT_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 SPPT_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 SPPT_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 SPPT_PERSMIN time intervals, 70 * but no more frequently than the current estimate of round-trip 71 * packet time. The SPPT_PERSIST timer is cleared whenever we receive 72 * a window update from the peer. 73 * 74 * The SPPT_KEEP timer is used to keep connections alive. If an 75 * connection is idle (no segments received) for SPPTV_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 SPPT_KEEP 81 * initiated segments we cannot elicit a response from a peer in SPPT_MAXIDLE 82 * amount of time, then we drop the connection. 83 */ 84 85 #define SPP_TTL 30 /* default time to live for SPP segs */ 86 /* 87 * Time constants. 88 */ 89 #define SPPTV_MSL ( 15*PR_SLOWHZ) /* max seg lifetime */ 90 #define SPPTV_SRTTBASE 0 /* base roundtrip time; 91 if 0, no idea yet */ 92 #define SPPTV_SRTTDFLT ( 3*PR_SLOWHZ) /* assumed RTT if no info */ 93 94 #define SPPTV_PERSMIN ( 5*PR_SLOWHZ) /* retransmit persistance */ 95 #define SPPTV_PERSMAX ( 60*PR_SLOWHZ) /* maximum persist interval */ 96 97 #define SPPTV_KEEP ( 75*PR_SLOWHZ) /* keep alive - 75 secs */ 98 #define SPPTV_MAXIDLE ( 8*SPPTV_KEEP) /* maximum allowable idle 99 time before drop conn */ 100 101 #define SPPTV_MIN ( 1*PR_SLOWHZ) /* minimum allowable value */ 102 #define SPPTV_REXMTMAX ( 64*PR_SLOWHZ) /* max allowable REXMT value */ 103 104 #define SPP_LINGERTIME 120 /* linger at most 2 minutes */ 105 106 #define SPP_MAXRXTSHIFT 12 /* maximum retransmits */ 107 108 #ifdef SPPTIMERS 109 char *spptimers[] = 110 { "REXMT", "PERSIST", "KEEP", "2MSL" }; 111 #endif 112 113 /* 114 * Force a time value to be in a certain range. 115 */ 116 #define SPPT_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 125 extern int spp_backoff[]; 126 #endif 127 128 #endif 129