From owner-freebsd-net Wed Apr 5 12:34:56 2000 Delivered-To: freebsd-net@freebsd.org Received: from ausmail2.austin.ibm.com (ausmail2.austin.ibm.com [192.35.232.11]) by hub.freebsd.org (Postfix) with ESMTP id 6911F37BB76 for ; Wed, 5 Apr 2000 12:34:43 -0700 (PDT) (envelope-from venkats@austin.ibm.com) Received: from netmail1.austin.ibm.com (netmail1.austin.ibm.com [9.53.250.96]) by ausmail2.austin.ibm.com (8.9.1/8.8.5) with ESMTP id OAA23306 for ; Wed, 5 Apr 2000 14:32:12 -0500 Received: from austin.ibm.com (ambika.austin.ibm.com [9.53.150.77]) by netmail1.austin.ibm.com (8.8.5/8.8.5) with ESMTP id OAA09362; Wed, 5 Apr 2000 14:34:38 -0500 Message-ID: <38EB954E.80EBB6FE@austin.ibm.com> Date: Wed, 05 Apr 2000 14:34:38 -0500 From: venkat venkatsubra Organization: IBM X-Mailer: Mozilla 4.61 [en] (X11; U; AIX 4.3) X-Accept-Language: en MIME-Version: 1.0 To: jayanth Cc: net@FreeBSD.ORG Subject: Re: Simultaneous close .... References: <20000404095017.B15820@yahoo-inc.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org Jayanth, This case is discussed in Wright & Stevens Vol.2 of TCP/IP Illustrated - Excercise 29.5. The suggested fix in the book is to remove the TH_FIN flag in tcp_outflags[] for the tcp CLOSING state. Because, the problem here was the retransmission of the FINs from both ends after receiving the other end's FIN. Venkat jayanth wrote: > I was testing b/w two 4.0 boxes and saw the following scenario. > > Server side > ----------- > 10:14:41.260613 server.7000 > client.1136: P 1:101(100) ack 32001 win 65535 (DF) > 10:14:41.260709 server.7000 > client.1136: F 101:101(0) ack 32001 win 65535 (DF) > 10:14:41.652936 client.1136 > server.7000: F 32001:32001(0) ack 101 win 17520 (D > F) > 10:14:41.653075 server.7000 > client.1136: F 101:101(0) ack 32002 win 65535 (DF) > 10:14:41.659388 client.1136 > server.7000: F 32001:32001(0) ack 102 win 17520 (D > F) > 10:14:41.659485 server.7000 > client.1136: . ack 32002 win 65535 (DF) > 10:14:41.989824 client.1136 > server.7000: . ack 102 win 17520 (DF) > > Client side > ----------- > 18:10:18.484731 server.7000 > client.1136: P 1:101(100) ack 32001 win 65535 (DF > ) > 18:10:18.485193 client.1136 > server.7000: F 32001:32001(0) ack 101 win 17520 (D > F) > 18:10:18.490679 server.7000 > client.1136: F 101:101(0) ack 32001 win 65535 (DF) > 18:10:18.490726 client.1136 > server.7000: F 32001:32001(0) ack 102 win 17520 (D > F) > 18:10:18.818621 server.7000 > client.1136: F 101:101(0) ack 32002 win 65535 (DF) > 18:10:18.818626 server.7000 > client.1136: . ack 32002 win 65535 (DF) > 18:10:18.818663 client.1136 > server.7000: . ack 102 win 17520 (DF) > > If I remember right the last two ACKS are not necessary during > simultaneous close? > > jayanth > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-net" in the body of the message To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message