From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755969Ab0JDRcM (ORCPT ); Mon, 4 Oct 2010 13:32:12 -0400 Received: from mail-ew0-f46.google.com ([209.85.215.46]:33713 "EHLO mail-ew0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754340Ab0JDRcK (ORCPT ); Mon, 4 Oct 2010 13:32:10 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:from:to:cc:subject:date:message-id:x-mailer; b=ro2ivyLPvDM91GBkmOZIifAaM/WVL41hXFCDQGrGlhpR61V5ezBfLBVH+BS/Z0iFvS A9ROdV9Ha94La4kTkmWuN3RYS9nT5jBn4tKj4UPmwFq4mgnDadOzav9gHZK7EpUWjo31 hn0cYhuYRKpjgI17S20ONrMu1NZKXbkfMvulI= From: Sami Kerola To: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org, davem@davemloft.net, Sami Kerola Subject: [PATCH] Documentation/networking/ip-sysctl.txt tcp_tw_recycle & tcp_tw_reuse Date: Mon, 4 Oct 2010 19:32:04 +0200 Message-Id: <1286213524-4659-1-git-send-email-kerolasa@iki.fi> X-Mailer: git-send-email 1.7.3.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sami Kerola Instead of saying 'consult your technical export' the documentation needs to assist an export to decide whether to keep these settings off or set them on. Signed-off-by: Sami Kerola --- Documentation/networking/ip-sysctl.txt | 20 +++++++++++++------- 1 files changed, 13 insertions(+), 7 deletions(-) diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index f350c69..01e2948 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -444,15 +444,21 @@ tcp_tso_win_divisor - INTEGER Default: 3 tcp_tw_recycle - BOOLEAN - Enable fast recycling TIME-WAIT sockets. Default value is 0. - It should not be changed without advice/request of technical - experts. + Enable fast recycling TIME-WAIT sockets. See also caution + wrote to tcp_tw_reuse. Default value is 0. tcp_tw_reuse - BOOLEAN - Allow to reuse TIME-WAIT sockets for new connections when it is - safe from protocol viewpoint. Default value is 0. - It should not be changed without advice/request of technical - experts. + Allow to reuse TIME-WAIT sockets for new connections when it is safe + from protocol viewpoint. One should enable also tcp_timestamps when + this is enabled. Default value is 0. + + Caution. Both tcp_tw_recycle and tcp_tw_reuse can cause problems. You + should not enable either without being sure about network topology in + between node(s) which are using, or used by, the node(s) where the + parameter is enabled. Connections that go via TCP state aware nodes, + such as firewalls, NAT devices or load balancers may start drop frames + because of the setting. The more there are connections the greater is + the likelyhood you will see this issue. tcp_window_scaling - BOOLEAN Enable window scaling as defined in RFC1323. -- 1.7.3.1