Date: Tue, 12 Oct 1999 16:28:45 +0200 From: Jacopo Pecci <em8jaci@etek.chalmers.se> To: net@freebsd.org Subject: delayed ACKs Message-ID: <8686.991012@etek.chalmers.se>
next in thread | raw e-mail | index | archive | help
According to what I have studied, delayed ACKs can be sent:
(1)every 200 ms
(2)when I have data to send (piggyback packet)
(3)every second packet
so I don't understand why in the example below, there are ACKs that
acknowledge up to 7 segments. (in the example I have just sent 50
segments of 1460 bytes from the client to the server)
15:58:26.565899 172.20.1.15.1034 > 172.20.2.15.1111: S 1085244744:1085244744(0) win 16384 <mss 1460> (DF)
15:58:26.566236 172.20.2.15.1111 > 172.20.1.15.1034: S 242000411:242000411(0) ack 1085244745 win 17520 <mss 1460> (DF)
15:58:26.566438 172.20.1.15.1034 > 172.20.2.15.1111: . ack 1 win 17520 (DF)
15:58:26.662625 172.20.1.15.1034 > 172.20.2.15.1111: . 1:1461(1460) ack 1 win 17520 (DF)
15:58:26.781386 172.20.2.15.1111 > 172.20.1.15.1034: . ack 1461 win 17520 (DF)
^^^^^^^
15:58:26.782287 172.20.1.15.1034 > 172.20.2.15.1111: . 1461:2921(1460) ack 1 win 17520 (DF)
15:58:26.783086 172.20.1.15.1034 > 172.20.2.15.1111: . 2921:4381(1460) ack 1 win 17520 (DF)
15:58:26.784675 172.20.2.15.1111 > 172.20.1.15.1034: . ack 4381 win 17520 (DF)
^^^^^^^^^
15:58:26.785521 172.20.1.15.1034 > 172.20.2.15.1111: . 4381:5841(1460) ack 1 win 17520 (DF)
15:58:26.786299 172.20.1.15.1034 > 172.20.2.15.1111: . 5841:7301(1460) ack 1 win 17520 (DF)
15:58:26.787074 172.20.1.15.1034 > 172.20.2.15.1111: . 7301:8761(1460) ack 1 win 17520 (DF)
15:58:26.788639 172.20.2.15.1111 > 172.20.1.15.1034: . ack 7301 win 17520 (DF)
^^^^^^^^^^^
15:58:26.789477 172.20.1.15.1034 > 172.20.2.15.1111: . 8761:10221(1460) ack 1 win 17520 (DF)
15:58:26.790255 172.20.1.15.1034 > 172.20.2.15.1111: . 10221:11681(1460) ack 1 win 17520 (DF)
15:58:26.791029 172.20.1.15.1034 > 172.20.2.15.1111: . 11681:13141(1460) ack 1 win 17520 (DF)
15:58:26.792614 172.20.2.15.1111 > 172.20.1.15.1034: . ack 10221 win 17520 (DF)
....... ^^^^^^^^^^^
according with point (3) each ACK acknowledges 2 packets but later....
15:58:26.793455 172.20.1.15.1034 > 172.20.2.15.1111: . 13141:14601(1460) ack 1 win 17520 (DF)
15:58:26.794232 172.20.1.15.1034 > 172.20.2.15.1111: . 14601:16061(1460) ack 1 win 17520 (DF)
15:58:26.795007 172.20.1.15.1034 > 172.20.2.15.1111: . 16061:17521(1460) ack 1 win 17520 (DF)
15:58:26.796695 172.20.2.15.1111 > 172.20.1.15.1034: . ack 13141 win 17520 (DF)
15:58:26.796750 172.20.2.15.1111 > 172.20.1.15.1034: . ack 16061 win 17520 (DF)
^^^^^^^^^^^
15:58:26.797580 172.20.1.15.1034 > 172.20.2.15.1111: . 17521:18981(1460) ack 1 win 17520 (DF)
15:58:26.798349 172.20.1.15.1034 > 172.20.2.15.1111: . 18981:20441(1460) ack 1 win 17520 (DF)
15:58:26.799119 172.20.1.15.1034 > 172.20.2.15.1111: . 20441:21901(1460) ack 1 win 17520 (DF)
15:58:26.800083 172.20.1.15.1034 > 172.20.2.15.1111: . 21901:23361(1460) ack 1 win 17520 (DF)
15:58:26.801295 172.20.1.15.1034 > 172.20.2.15.1111: . 23361:24821(1460) ack 1 win 17520 (DF)
15:58:26.802540 172.20.1.15.1034 > 172.20.2.15.1111: . 24821:26281(1460) ack 1 win 17520 (DF)
15:58:26.865477 172.20.2.15.1111 > 172.20.1.15.1034: . ack 26281 win 10372 (DF)
^^^^^^^^^^
15:58:26.866343 172.20.1.15.1034 > 172.20.2.15.1111: . 26281:27741(1460) ack 1 win 17520 (DF)
15:58:26.867117 172.20.1.15.1034 > 172.20.2.15.1111: . 27741:29201(1460) ack 1 win 17520 (DF)
15:58:26.867886 172.20.1.15.1034 > 172.20.2.15.1111: . 29201:30661(1460) ack 1 win 17520 (DF)
15:58:26.868837 172.20.1.15.1034 > 172.20.2.15.1111: . 30661:32121(1460) ack 1 win 17520 (DF)
15:58:26.870080 172.20.1.15.1034 > 172.20.2.15.1111: P 32121:33581(1460) ack 1 win 17520 (DF)
15:58:26.871290 172.20.1.15.1034 > 172.20.2.15.1111: . 33581:35041(1460) ack 1 win 17520 (DF)
15:58:26.872534 172.20.1.15.1034 > 172.20.2.15.1111: . 35041:36501(1460) ack 1 win 17520 (DF)
15:58:26.928674 172.20.2.15.1111 > 172.20.1.15.1034: . ack 36501 win 3224 (DF)
^^^^^^^^^^^^
15:58:26.928732 172.20.2.15.1111 > 172.20.1.15.1034: . ack 36501 win 6296 (DF)
...
it acknowledges first 16061 and then 26281 (7 segments)
thanks
/jaci
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-net" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?8686.991012>