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 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * Copyright (c) 1995, Mike Mitchell
30 *
31 * Redistribution and use in source and binary forms, with or without
32 * modification, are permitted provided that the following conditions
33 * are met:
34 * 1. Redistributions of source code must retain the above copyright
35 * notice, this list of conditions and the following disclaimer.
36 * 2. Redistributions in binary form must reproduce the above copyright
37 * notice, this list of conditions and the following disclaimer in the
38 * documentation and/or other materials provided with the distribution.
39 * 3. All advertising materials mentioning features or use of this software
40 * must display the following acknowledgement:
41 * This product includes software developed by the University of
42 * California, Berkeley and its contributors.
43 * 4. Neither the name of the University nor the names of its contributors
44 * may be used to endorse or promote products derived from this software
45 * without specific prior written permission.
46 *
47 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
48 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
49 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
50 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
51 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
52 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
53 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
54 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
55 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
56 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
57 * SUCH DAMAGE.
58 *
59 * @(#)spx_timer.h
60 *
61 * $FreeBSD: src/sys/netipx/spx_timer.h,v 1.12 2007/01/08 22:14:00 rwatson Exp $
62 */
63
64 #ifndef _NETIPX_SPX_TIMER_H_
65 #define _NETIPX_SPX_TIMER_H_
66
67 /*
68 * Definitions of the SPX timers. These timers are counted
69 * down PR_SLOWHZ times a second.
70 */
71 #define SPXT_REXMT 0 /* retransmit */
72 #define SPXT_PERSIST 1 /* retransmit persistence */
73 #define SPXT_KEEP 2 /* keep alive */
74 #define SPXT_2MSL 3 /* 2*msl quiet time timer */
75
76 /*
77 * The SPXT_REXMT timer is used to force retransmissions.
78 * The SPX has the SPXT_REXMT timer set whenever segments
79 * have been sent for which ACKs are expected but not yet
80 * received. If an ACK is received which advances tp->snd_una,
81 * then the retransmit timer is cleared (if there are no more
82 * outstanding segments) or reset to the base value (if there
83 * are more ACKs expected). Whenever the retransmit timer goes off,
84 * we retransmit one unacknowledged segment, and do a backoff
85 * on the retransmit timer.
86 *
87 * The SPXT_PERSIST timer is used to keep window size information
88 * flowing even if the window goes shut. If all previous transmissions
89 * have been acknowledged (so that there are no retransmissions in progress),
90 * and the window is too small to bother sending anything, then we start
91 * the SPXT_PERSIST timer. When it expires, if the window is nonzero,
92 * we go to transmit state. Otherwise, at intervals send a single byte
93 * into the peer's window to force him to update our window information.
94 * We do this at most as often as SPXT_PERSMIN time intervals,
95 * but no more frequently than the current estimate of round-trip
96 * packet time. The SPXT_PERSIST timer is cleared whenever we receive
97 * a window update from the peer.
98 *
99 * The SPXT_KEEP timer is used to keep connections alive. If an
100 * connection is idle (no segments received) for SPXTV_KEEP amount of time,
101 * but not yet established, then we drop the connection. If the connection
102 * is established, then we force the peer to send us a segment by sending:
103 * <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK>
104 * This segment is (deliberately) outside the window, and should elicit
105 * an ack segment in response from the peer. If, despite the SPXT_KEEP
106 * initiated segments we cannot elicit a response from a peer in SPXT_MAXIDLE
107 * amount of time, then we drop the connection.
108 */
109
110 #define SPX_TTL 30 /* default time to live for SPX segs */
111 /*
112 * Time constants.
113 */
114 #define SPXTV_MSL ( 15*PR_SLOWHZ) /* max seg lifetime */
115 #define SPXTV_SRTTBASE 0 /* base roundtrip time;
116 if 0, no idea yet */
117 #define SPXTV_SRTTDFLT ( 3*PR_SLOWHZ) /* assumed RTT if no info */
118
119 #define SPXTV_PERSMIN ( 5*PR_SLOWHZ) /* retransmit persistence */
120 #define SPXTV_PERSMAX ( 60*PR_SLOWHZ) /* maximum persist interval */
121
122 #define SPXTV_KEEP ( 75*PR_SLOWHZ) /* keep alive - 75 secs */
123 #define SPXTV_MAXIDLE ( 8*SPXTV_KEEP) /* maximum allowable idle
124 time before drop conn */
125
126 #define SPXTV_MIN ( 1*PR_SLOWHZ) /* minimum allowable value */
127 #define SPXTV_REXMTMAX ( 64*PR_SLOWHZ) /* max allowable REXMT value */
128
129 #define SPX_LINGERTIME 120 /* linger at most 2 minutes */
130
131 #define SPX_MAXRXTSHIFT 12 /* maximum retransmits */
132
133 #ifdef SPXTIMERS
134 char *spxtimers[] =
135 { "REXMT", "PERSIST", "KEEP", "2MSL" };
136 #endif
137
138 /*
139 * Force a time value to be in a certain range.
140 */
141 #define SPXT_RANGESET(tv, value, tvmin, tvmax) { \
142 (tv) = (value); \
143 if ((tv) < (tvmin)) \
144 (tv) = (tvmin); \
145 else if ((tv) > (tvmax)) \
146 (tv) = (tvmax); \
147 }
148
149 #endif /* !_NETIPX_SPX_TIMER_H_ */
150
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