From owner-freebsd-net@FreeBSD.ORG Mon May 22 11:57:23 2006 Return-Path: X-Original-To: freebsd-net@freebsd.org Delivered-To: freebsd-net@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 6DEAA16A4EA for ; Mon, 22 May 2006 11:57:23 +0000 (UTC) (envelope-from nitro@263.net) Received: from smtp.263.net (263.net.cn [211.150.96.21]) by mx1.FreeBSD.org (Postfix) with ESMTP id 29C1643D58 for ; Mon, 22 May 2006 11:57:21 +0000 (GMT) (envelope-from nitro@263.net) Received: from intron.ac (unknown [127.0.0.1]) by smtp.263.net (Postfix) with SMTP id 15918F1590 for ; Mon, 22 May 2006 19:57:22 +0800 (CST) X-KSVirus-check: 0 From: mag@intron.ac To: freebsd-net@freebsd.org Date: Mon, 22 May 2006 19:51:33 +0800 Mime-Version: 1.0 Content-Type: text/plain; charset="gb2312"; format=flowed Content-Transfer-Encoding: 7bit Message-Id: <20060522115722.15918F1590@smtp.263.net> Subject: How to Quicken TCP Re-transmission? 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: Mon, 22 May 2006 11:57:26 -0000 Hi, I want to transmit data between host A and host B. The link between these two hosts is really bad: PING reports 30% packet loss and about 60 ms return delay. This means if timed out for 1 second, the data must have been lost. I keep "net.inet.tcp.rexmit_min" and "net.inet.tcp.rexmit_slop" untouched. But TCPDUMP tells me that if some data are lost, re-transmission will be done 64 seconds after last transmission! How to quicken TCP re-transmission? How to tune "net.inet.tcp.rexmit_min" and "net.inet.tcp.rexmit_slop"? ------------------------------------------------------------------------ From Beijing, China