Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S268051AbUIBJYL (ORCPT ); Thu, 2 Sep 2004 05:24:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268115AbUIBJYL (ORCPT ); Thu, 2 Sep 2004 05:24:11 -0400 Received: from rproxy.gmail.com ([64.233.170.198]:34284 "EHLO mproxy.gmail.com") by vger.kernel.org with ESMTP id S268051AbUIBJVq (ORCPT ); Thu, 2 Sep 2004 05:21:46 -0400 Message-ID: <93e09f0104090202216403c08d@mail.gmail.com> Date: Thu, 2 Sep 2004 14:51:46 +0530 From: Rohit Neupane Reply-To: Rohit Neupane To: linux-kernel@vger.kernel.org Subject: Weird Problem with TCP Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3576 Lines: 85 Hi, I have a linux box which acts as gateway and b/w manager for our wireless network. I have 3 Interfaces ( one not is use yet). I have created 3 aliases on the interface connected to the wireless (with 3 different class C address). I have around 350-400 wireless clients with over 10Mbps traffic at peak hours. These days I have observed some abnormal behavior. System: Dell P4 Poweredge Red Hat 8.0 with 2.4.25 kernel Lan Cards: 1. Intel 82540EM Gigabit Ethernet Controller (Intenet) 2. 3com 3c905B Cyclone (Wireless) The problem is: * Everything works fine for about 5-10 mins then all of a sudden TCP services are not accessable. * For some reason TCP times out. However at the same time ping,traceroute and dns trace works without any problem. * The connected TCP sokets keeps working without any problem. I verified this by using Msn chat. I observerd that I chat session ( which I had started when everything was normal) continued without any problem however I was not able to initiate a new chat session. Result of tcpdum on eth0 (internet) and eth2(wireless) * I can see tcp SYN request coming in from eth2 (from client) and going out via eth0 to destination. * I can see tcp SYN+ACK coming in from eth0. But it doesn't get out through eth2 !!! However other udp,icmp pkts can. src 69.56.37.146 , dst 64.236.16.52 this is tcpdump on eth0 (internet side) 17:14:32.003370 69.56.37.146.3170 > 64.236.16.52.http: S 2446361626:2446361626(0) win 64240 (DF) 17:14:32.004694 64.236.16.52.http > 69.56.37.146.3170: S 3641974278:3641974278(0) ack 2446361627 win 65535 (DF) 17:14:34.920578 69.56.37.146.3170 > 64.236.16.52.http: S 2446361626:2446361626(0) win 64240 (DF) 17:14:34.921800 64.236.16.52.http > 69.56.37.146.3170: S 3641974278:3641974278(0) ack 2446361627 win 65535 (DF) 17:14:37.915564 64.236.16.52.http > 69.56.37.146.3170: S 3641974278:3641974278(0) ack 2446361627 win 65535 (DF) 17:14:40.955491 69.56.37.146.3170 > 64.236.16.52.http: S 2446361626:2446361626(0) win 64240 (DF) 17:14:40.957682 64.236.16.52.http > 69.56.37.146.3170: S 3641974278:3641974278(0) ack 2446361627 win 65535 (DF) this is tcpdump on eth2 (client side) 17:14:32.003179 69.56.37.146.3170 > 64.236.16.52.http: S 2446361626:2446361626(0) win 64240 (DF) 17:14:34.920212 69.56.37.146.3170 > 64.236.16.52.http: S 2446361626:2446361626(0) win 64240 (DF) 17:14:40.955257 69.56.37.146.3170 > 64.236.16.52.http: S 2446361626:2446361626(0) win 64240 (DF) As you can see i am getting the ACK from source from seq. 2446361626 (with ack 2446361627 ) on eth0. But it is not going out via eth2!! After sometime everthing starts working normally again. So what may be the problem? I have problem only with the tcp protocol and not with other. I haven't changed any tcp memory related settings. net.ipv4.tcp_rmem = 4096 87380 174760 net.ipv4.tcp_wmem = 4096 87380 174760 net.ipv4.tcp_mem = 195584 196096 196608 net.core.optmem_max = 10240 net.core.rmem_default = 65535 net.core.wmem_default = 65535 net.core.rmem_max = 131071 net.core.wmem_max = 131071 Has anyone come across this probelm? any suggestion? Thanks Rohit - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/