From owner-freebsd-net@FreeBSD.ORG Fri Apr 27 20:33:11 2007 Return-Path: X-Original-To: freebsd-net@freebsd.org Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 0E0E016A401 for ; Fri, 27 Apr 2007 20:33:11 +0000 (UTC) (envelope-from nataraja@cis.udel.edu) Received: from mail.eecis.udel.edu (louie.udel.edu [128.4.40.12]) by mx1.freebsd.org (Postfix) with ESMTP id D5D4013C44C for ; Fri, 27 Apr 2007 20:33:10 +0000 (UTC) (envelope-from nataraja@cis.udel.edu) Received: by mail.eecis.udel.edu (Postfix, from userid 62) id 560173DA2; Fri, 27 Apr 2007 16:33:06 -0400 (EDT) X-Spam-Checker-Version: SpamAssassin 3.1.8 (2007-02-13) on louie.udel.edu X-Spam-Level: X-Spam-Status: No, score=-22.3 required=4.1 tests=ALL_TRUSTED,AWL,BAYES_00, LOCAL_AUTH_RCVD autolearn=ham version=3.1.8 Received: from [128.175.192.45] (roaming-192-45.nss.udel.edu [128.175.192.45]) (Authenticated sender: nataraja@mail.eecis.udel.edu) by mail.eecis.udel.edu (Postfix) with ESMTP id E28183CAB; Fri, 27 Apr 2007 16:33:04 -0400 (EDT) Message-ID: <46325DFC.7020006@cis.udel.edu> Date: Fri, 27 Apr 2007 16:33:00 -0400 From: Preethi Natarajan User-Agent: Thunderbird 1.5.0.4 (Windows/20060516) To: Mike Silbersack References: <463214E4.9090401@cis.udel.edu> In-Reply-To: X-Sanitizer: This message has been sanitized! X-Sanitizer-URL: http://mailtools.anomy.net/ X-Sanitizer-Rev: UDEL-ECECIS: Sanitizer.pm, v 1.64 2002/10/22 MIME-Version: 1.0 MIME-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-net@freebsd.org, "Paul D. Amer" Subject: Re: TCP Delayed Ack implementation in 6.1 X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 27 Apr 2007 20:33:11 -0000 Hello, The reason for the second ack appears to be a new window update at the client side. The push flag was not set. Thanks, Preethi On 4/27/2007 4:25 PM, Mike Silbersack wrote: > On Fri, 27 Apr 2007, Preethi Natarajan wrote: > > >> From tcpdump at client side: >> Time: 38s.695ms: S->C data (282b) >> Time: 38s.707ms: S->C data (1448b) >> Time: 38s.707ms: C->S ack >> Time: 38s.719ms: S->C data (1448b) >> Time: 38s.719ms: C->S ack >> Time: 38s.731ms: S->C data (1448b) >> Time: 38s.741ms: S->C data (1166b) >> Time: 38s.741ms: C->S ack >> >> I do not understand the reason for the second ack from C->S (Time >> 38s.719ms). Clearly this ack has not delayed for 200ms from the previous >> ack and acks only 1 packet. Am I missing something? >> >> Thanks a ton, >> Preethi >> > > My crystal ball tells me that packet four has the PUSH flag set on it, > which means that it will be immediately ACKed and sent to the application. > > Please post tcpdump output in the future, the batteries on my crystal ball > are running low. > > Mike "Silby" Silbersack >