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1.1 root 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, 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 7.3 (Berkeley) 6/28/90
34: */
35:
36: /*
37: * Definitions of the SPP timers. These timers are counted
38: * down PR_SLOWHZ times a second.
39: */
40: #define SPPT_NTIMERS 4
41:
42: #define SPPT_REXMT 0 /* retransmit */
43: #define SPPT_PERSIST 1 /* retransmit persistance */
44: #define SPPT_KEEP 2 /* keep alive */
45: #define SPPT_2MSL 3 /* 2*msl quiet time timer */
46:
47: /*
48: * The SPPT_REXMT timer is used to force retransmissions.
49: * The SPP has the SPPT_REXMT timer set whenever segments
50: * have been sent for which ACKs are expected but not yet
51: * received. If an ACK is received which advances tp->snd_una,
52: * then the retransmit timer is cleared (if there are no more
53: * outstanding segments) or reset to the base value (if there
54: * are more ACKs expected). Whenever the retransmit timer goes off,
55: * we retransmit one unacknowledged segment, and do a backoff
56: * on the retransmit timer.
57: *
58: * The SPPT_PERSIST timer is used to keep window size information
59: * flowing even if the window goes shut. If all previous transmissions
60: * have been acknowledged (so that there are no retransmissions in progress),
61: * and the window is too small to bother sending anything, then we start
62: * the SPPT_PERSIST timer. When it expires, if the window is nonzero,
63: * we go to transmit state. Otherwise, at intervals send a single byte
64: * into the peer's window to force him to update our window information.
65: * We do this at most as often as SPPT_PERSMIN time intervals,
66: * but no more frequently than the current estimate of round-trip
67: * packet time. The SPPT_PERSIST timer is cleared whenever we receive
68: * a window update from the peer.
69: *
70: * The SPPT_KEEP timer is used to keep connections alive. If an
71: * connection is idle (no segments received) for SPPTV_KEEP amount of time,
72: * but not yet established, then we drop the connection. If the connection
73: * is established, then we force the peer to send us a segment by sending:
74: * <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK>
75: * This segment is (deliberately) outside the window, and should elicit
76: * an ack segment in response from the peer. If, despite the SPPT_KEEP
77: * initiated segments we cannot elicit a response from a peer in SPPT_MAXIDLE
78: * amount of time, then we drop the connection.
79: */
80:
81: #define SPP_TTL 30 /* default time to live for SPP segs */
82: /*
83: * Time constants.
84: */
85: #define SPPTV_MSL ( 15*PR_SLOWHZ) /* max seg lifetime */
86: #define SPPTV_SRTTBASE 0 /* base roundtrip time;
87: if 0, no idea yet */
88: #define SPPTV_SRTTDFLT ( 3*PR_SLOWHZ) /* assumed RTT if no info */
89:
90: #define SPPTV_PERSMIN ( 5*PR_SLOWHZ) /* retransmit persistance */
91: #define SPPTV_PERSMAX ( 60*PR_SLOWHZ) /* maximum persist interval */
92:
93: #define SPPTV_KEEP ( 75*PR_SLOWHZ) /* keep alive - 75 secs */
94: #define SPPTV_MAXIDLE ( 8*SPPTV_KEEP) /* maximum allowable idle
95: time before drop conn */
96:
97: #define SPPTV_MIN ( 1*PR_SLOWHZ) /* minimum allowable value */
98: #define SPPTV_REXMTMAX ( 64*PR_SLOWHZ) /* max allowable REXMT value */
99:
100: #define SPP_LINGERTIME 120 /* linger at most 2 minutes */
101:
102: #define SPP_MAXRXTSHIFT 12 /* maximum retransmits */
103:
104: #ifdef SPPTIMERS
105: char *spptimers[] =
106: { "REXMT", "PERSIST", "KEEP", "2MSL" };
107: #endif
108:
109: /*
110: * Force a time value to be in a certain range.
111: */
112: #define SPPT_RANGESET(tv, value, tvmin, tvmax) { \
113: (tv) = (value); \
114: if ((tv) < (tvmin)) \
115: (tv) = (tvmin); \
116: else if ((tv) > (tvmax)) \
117: (tv) = (tvmax); \
118: }
119:
120: #ifdef KERNEL
121: extern int spp_backoff[];
122: #endif
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