not doing *anything* while waiting for input; add substate

[unix-history] / usr / src / sys / netinet / tcp_timer.h

diff --git a/usr/src/sys/netinet/tcp_timer.h b/usr/src/sys/netinet/tcp_timer.h
index bbc4765..17eb118 100644 (file)
--- a/usr/src/sys/netinet/tcp_timer.h
+++ b/usr/src/sys/netinet/tcp_timer.h
@@ -1,18 +1,27 @@
-/*     tcp_timer.h     4.8     82/06/06        */
+/*
+ * Copyright (c) 1982, 1986 Regents of the University of California.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms are permitted
+ * provided that this notice is preserved and that due credit is given
+ * to the University of California at Berkeley. The name of the University
+ * may not be used to endorse or promote products derived from this
+ * software without specific prior written permission. This software
+ * is provided ``as is'' without express or implied warranty.
+ *
+ *     @(#)tcp_timer.h 7.5 (Berkeley) %G%
+ */

 
 /*
  * Definitions of the TCP timers.  These timers are counted
  * down PR_SLOWHZ times a second.
  */
 
 /*
  * Definitions of the TCP timers.  These timers are counted
  * down PR_SLOWHZ times a second.
  */

-#define        TCPT_NTIMERS    5
+#define        TCPT_NTIMERS    4

 
 #define        TCPT_REXMT      0               /* retransmit */
 #define        TCPT_PERSIST    1               /* retransmit persistance */
 #define        TCPT_KEEP       2               /* keep alive */
 #define        TCPT_2MSL       3               /* 2*msl quiet time timer */
 
 #define        TCPT_REXMT      0               /* retransmit */
 #define        TCPT_PERSIST    1               /* retransmit persistance */
 #define        TCPT_KEEP       2               /* keep alive */
 #define        TCPT_2MSL       3               /* 2*msl quiet time timer */

-#ifdef TCPTRUEOOB
-#define        TCPT_OOBREXMT   4               /* out-of-band rexmt */
-#endif

 
 /*
  * The TCPT_REXMT timer is used to force retransmissions.
 
 /*
  * The TCPT_REXMT timer is used to force retransmissions.


@@ -22,78 +31,63 @@
  * 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,
  * 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 all unacknowledged segments, and do an exponential
- * backoff on the retransmit timer.
+ * we retransmit one unacknowledged segment, and do a backoff
+ * on the retransmit timer.

  *
  * The TCPT_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),
  *
  * The TCPT_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 shut, then we start the TCPT_PERSIST timer, and at
- * intervals send a single byte into the peers window to force him to update
- * our window information.  We do this at most as often as TCPT_PERSMIN
- * time intervals, but no more frequently than the current estimate of
- * round-trip packet time.  The TCPT_PERSIST timer is cleared whenever
- * we receive a window update from the peer.
+ * and the window is too small to bother sending anything, then we start
+ * the TCPT_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 TCPT_PERSMIN time intervals,
+ * but no more frequently than the current estimate of round-trip
+ * packet time.  The TCPT_PERSIST timer is cleared whenever we receive
+ * a window update from the peer.

  *
  * The TCPT_KEEP timer is used to keep connections alive.  If an
  *
  * The TCPT_KEEP timer is used to keep connections alive.  If an

- * connection is idle (no segments received) for TCPTV_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:
+ * connection is idle (no segments received) for TCPTV_KEEP_INIT amount of time,
+ * but not yet established, then we drop the connection.  Once the connection
+ * is established, if the connection is idle for TCPTV_KEEP_IDLE time
+ * (and keepalives have been enabled on the socket), we begin to probe
+ * the connection.  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 TCPT_KEEP
  * initiated segments we cannot elicit a response from a peer in TCPT_MAXIDLE
  *     <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 TCPT_KEEP
  * initiated segments we cannot elicit a response from a peer in TCPT_MAXIDLE

- * amount of time, then we drop the connection.
- *
- * The OOBREXMT timer is to force retransmissions of out-of-band indications.
- * Because out-of-band data is considered critical, it does not exponential
- * backoff, but runs at a multiple of smoothed round trip time until acked.
+ * amount of time probing, then we drop the connection.

  */
 
  */
 

-#define        TCP_TTL         15              /* time to live for TCP segs */
+#define        TCP_TTL         30              /* default time to live for TCP segs */

 /*
  * Time constants.
  */
 /*
  * Time constants.
  */

-#define        TCPTV_MSL       ( 30*PR_SLOWHZ)         /* max seg lifetime */
-#define        TCPTV_SRTTBASE  (  1*PR_SLOWHZ)         /* base roundtrip time */
-#define        TCPTV_KEEP      ( 45*PR_SLOWHZ)         /* keep alive - 45 secs */
+#define        TCPTV_MSL       ( 30*PR_SLOWHZ)         /* max seg lifetime (hah!) */
+#define        TCPTV_SRTTBASE  0                       /* base roundtrip time;
+                                                  if 0, no idea yet */
+#define        TCPTV_SRTTDFLT  (  3*PR_SLOWHZ)         /* assumed RTT if no info */
+

 #define        TCPTV_PERSMIN   (  5*PR_SLOWHZ)         /* retransmit persistance */
 #define        TCPTV_PERSMIN   (  5*PR_SLOWHZ)         /* retransmit persistance */

+#define        TCPTV_PERSMAX   ( 60*PR_SLOWHZ)         /* maximum persist interval */

 
 

-#define        TCPTV_MAXIDLE   (  8*TCPTV_KEEP)        /* maximum allowable idle
-                                                  time before drop conn */
+#define        TCPTV_KEEP_INIT ( 75*PR_SLOWHZ)         /* initial connect keep alive */
+#define        TCPTV_KEEP_IDLE (120*60*PR_SLOWHZ)      /* dflt time before probing */
+#define        TCPTV_KEEPINTVL ( 75*PR_SLOWHZ)         /* default probe interval */
+#define        TCPTV_KEEPCNT   8                       /* max probes before drop */

 
 #define        TCPTV_MIN       (  1*PR_SLOWHZ)         /* minimum allowable value */
 
 #define        TCPTV_MIN       (  1*PR_SLOWHZ)         /* minimum allowable value */

-#define        TCPTV_MAX       ( 30*PR_SLOWHZ)         /* maximum allowable value */
+#define        TCPTV_REXMTMAX  ( 64*PR_SLOWHZ)         /* max allowable REXMT value */

 
 #define        TCP_LINGERTIME  120                     /* linger at most 2 minutes */
 
 
 #define        TCP_LINGERTIME  120                     /* linger at most 2 minutes */
 

-#define        TCP_MAXRXTSHIFT 10                      /* maximum retransmits */
+#define        TCP_MAXRXTSHIFT 12                      /* maximum retransmits */

 
 #ifdef TCPTIMERS
 char *tcptimers[] =
 
 #ifdef TCPTIMERS
 char *tcptimers[] =

-    { "REXMT", "PERSIST", "KEEP", "2MSL", "OOBREXMT" };
+    { "REXMT", "PERSIST", "KEEP", "2MSL" };

 #endif
 
 #endif
 

-/*
- * Retransmission smoothing constants.
- * Smoothed round trip time is updated by
- *    tp->t_srtt = (tcp_alpha * tp->t_srtt) + ((1 - tcp_alpha) * tp->t_rtt)
- * each time a new value of tp->t_rtt is available.  The initial
- * retransmit timeout is then based on
- *    tp->t_timer[TCPT_REXMT] = tcp_beta * tp->t_srtt;
- * limited, however to be at least TCPTV_REXMTLO and at most TCPTV_REXMTHI.
- */
-float  tcp_alpha, tcp_beta;
-
-/*
- * Initial values of tcp_alpha and tcp_beta.
- * These are conservative: averaging over a long
- * period of time, and allowing for large individual deviations from
- * tp->t_srtt.
- */
-#define        TCP_ALPHA       0.9
-#define        TCP_BETA        2.0
-

 /*
  * Force a time value to be in a certain range.
  */
 /*
  * Force a time value to be in a certain range.
  */


@@ -101,6 +95,14 @@ float       tcp_alpha, tcp_beta;
        (tv) = (value); \
        if ((tv) < (tvmin)) \
                (tv) = (tvmin); \
        (tv) = (value); \
        if ((tv) < (tvmin)) \
                (tv) = (tvmin); \

-       if ((tv) > (tvmax)) \
+       else if ((tv) > (tvmax)) \

                (tv) = (tvmax); \
 }
                (tv) = (tvmax); \
 }

+
+#ifdef KERNEL
+extern int tcp_keepidle;               /* time before keepalive probes begin */
+extern int tcp_keepintvl;              /* time between keepalive probes */
+extern int tcp_maxidle;                        /* time to drop after starting probes */
+extern int tcp_ttl;                    /* time to live for TCP segs */
+extern int tcp_backoff[];
+#endif