BSD 4_3_Tahoe release

[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 d6071fd..a63699e 100644 (file)
--- a/usr/src/sys/netinet/tcp_timer.h
+++ b/usr/src/sys/netinet/tcp_timer.h
@@ -1,9 +1,20 @@
 /*
  * Copyright (c) 1982, 1986 Regents of the University of California.
 /*
  * Copyright (c) 1982, 1986 Regents of the University of California.

- * All rights reserved.  The Berkeley software License Agreement
- * specifies the terms and conditions for redistribution.
+ * All rights reserved.

  *
  *

- *     @(#)tcp_timer.h 7.1 (Berkeley) 6/5/86
+ * Redistribution and use in source and binary forms are permitted
+ * provided that the above copyright notice and this paragraph are
+ * duplicated in all such forms and that any documentation,
+ * advertising materials, and other materials related to such
+ * distribution and use acknowledge that the software was developed
+ * by the University of California, 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'' AND WITHOUT ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
+ * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ *     @(#)tcp_timer.h 7.6 (Berkeley) 6/29/88

  */
 
 /*
  */
 
 /*


@@ -41,33 +52,37 @@
  * a window update from the peer.
  *
  * The TCPT_KEEP timer is used to keep connections alive.  If an
  * a window update from the peer.
  *
  * 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.
+ * amount of time probing, then we drop the connection.

  */
 
  */
 

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

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

-#define        TCPTV_MSL       ( 15*PR_SLOWHZ)         /* max seg lifetime */
+#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_SRTTBASE  0                       /* base roundtrip time;
                                                   if 0, no idea yet */
 #define        TCPTV_SRTTDFLT  (  3*PR_SLOWHZ)         /* assumed RTT if no info */
 

-#define        TCPTV_KEEP      ( 45*PR_SLOWHZ)         /* keep alive - 45 secs */

 #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 */
 


@@ -78,26 +93,6 @@ char *tcptimers[] =
     { "REXMT", "PERSIST", "KEEP", "2MSL" };
 #endif
 
     { "REXMT", "PERSIST", "KEEP", "2MSL" };
 #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_MIN and at most TCPTV_MAX.
- */
-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.
  */


@@ -105,6 +100,14 @@ 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