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/*
* Copyright (c) 1995, Mike Mitchell
* Copyright (c) 1982, 1986, 1988, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)spx_timer.h
*
* $Id: spx_timer.h,v 1.4 1995/11/04 09:03:39 julian Exp $
*/
#ifndef _NETIPX_SPX_TIMER_H_
#define _NETIPX_SPX_TIMER_H_
/*
* Definitions of the SPX timers. These timers are counted
* down PR_SLOWHZ times a second.
*/
#define SPXT_REXMT 0 /* retransmit */
#define SPXT_PERSIST 1 /* retransmit persistence */
#define SPXT_KEEP 2 /* keep alive */
#define SPXT_2MSL 3 /* 2*msl quiet time timer */
/*
* The SPXT_REXMT timer is used to force retransmissions.
* The SPX has the SPXT_REXMT timer set whenever segments
* have been sent for which ACKs are expected but not yet
* received. If an ACK is received which advances tp->snd_una,
* then the retransmit timer is cleared (if there are no more
* outstanding segments) or reset to the base value (if there
* are more ACKs expected). Whenever the retransmit timer goes off,
* we retransmit one unacknowledged segment, and do a backoff
* on the retransmit timer.
*
* The SPXT_PERSIST timer is used to keep window size information
* flowing even if the window goes shut. If all previous transmissions
* have been acknowledged (so that there are no retransmissions in progress),
* and the window is too small to bother sending anything, then we start
* the SPXT_PERSIST timer. When it expires, if the window is nonzero,
* we go to transmit state. Otherwise, at intervals send a single byte
* into the peer's window to force him to update our window information.
* We do this at most as often as SPXT_PERSMIN time intervals,
* but no more frequently than the current estimate of round-trip
* packet time. The SPXT_PERSIST timer is cleared whenever we receive
* a window update from the peer.
*
* The SPXT_KEEP timer is used to keep connections alive. If an
* connection is idle (no segments received) for SPXTV_KEEP amount of time,
* but not yet established, then we drop the connection. If the connection
* is established, then we force the peer to send us a segment by sending:
* <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK>
* This segment is (deliberately) outside the window, and should elicit
* an ack segment in response from the peer. If, despite the SPXT_KEEP
* initiated segments we cannot elicit a response from a peer in SPXT_MAXIDLE
* amount of time, then we drop the connection.
*/
#define SPX_TTL 30 /* default time to live for SPX segs */
/*
* Time constants.
*/
#define SPXTV_MSL ( 15*PR_SLOWHZ) /* max seg lifetime */
#define SPXTV_SRTTBASE 0 /* base roundtrip time;
if 0, no idea yet */
#define SPXTV_SRTTDFLT ( 3*PR_SLOWHZ) /* assumed RTT if no info */
#define SPXTV_PERSMIN ( 5*PR_SLOWHZ) /* retransmit persistence */
#define SPXTV_PERSMAX ( 60*PR_SLOWHZ) /* maximum persist interval */
#define SPXTV_KEEP ( 75*PR_SLOWHZ) /* keep alive - 75 secs */
#define SPXTV_MAXIDLE ( 8*SPXTV_KEEP) /* maximum allowable idle
time before drop conn */
#define SPXTV_MIN ( 1*PR_SLOWHZ) /* minimum allowable value */
#define SPXTV_REXMTMAX ( 64*PR_SLOWHZ) /* max allowable REXMT value */
#define SPX_LINGERTIME 120 /* linger at most 2 minutes */
#define SPX_MAXRXTSHIFT 12 /* maximum retransmits */
#ifdef SPXTIMERS
char *spxtimers[] =
{ "REXMT", "PERSIST", "KEEP", "2MSL" };
#endif
/*
* Force a time value to be in a certain range.
*/
#define SPXT_RANGESET(tv, value, tvmin, tvmax) { \
(tv) = (value); \
if ((tv) < (tvmin)) \
(tv) = (tvmin); \
else if ((tv) > (tvmax)) \
(tv) = (tvmax); \
}
#ifdef KERNEL
extern int spx_backoff[];
#endif
#endif
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