From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH] make _minimum_ TCP retransmission timeout configurable Date: Wed, 29 Aug 2007 16:15:28 -0700 (PDT) Message-ID: <20070829.161528.38309258.davem@davemloft.net> References: <46D5F32F.2070502@hp.com> <20070829.153503.18295527.davem@davemloft.net> <46D5FBF3.5050700@hp.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: ian.mcdonald@jandi.co.nz, netdev@vger.kernel.org, ilpo.jarvinen@helsinki.fi To: rick.jones2@hp.com Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:33827 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751407AbXH2XP3 (ORCPT ); Wed, 29 Aug 2007 19:15:29 -0400 In-Reply-To: <46D5FBF3.5050700@hp.com> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Rick Jones Date: Wed, 29 Aug 2007 16:06:27 -0700 > I belive the biggest component comes from link-layer retransmissions. > There can also be some short outtages thanks to signal blocking, > tunnels, people with big hats and whatnot that the link-layer > retransmissions are trying to address. The three seconds seems to be a > value that gives the certainty that 99 times out of 10 the segment was > indeed lost. > > The trace I've been sent shows clean RTTs ranging from ~200 milliseconds > to ~7000 milliseconds. Thanks for the info. It's pretty easy to generate examples where we might have some sockets talking over interfaces on such a network and others which are not. Therefore, if we do this, a per-route metric is probably the best bet. Ilpo, I'm also very interested to see what you think of all of this :-)