From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Daniel J Blueman" Subject: Re: time for TCP ECN defaulting to on? Date: Fri, 7 Nov 2008 13:43:40 +0000 Message-ID: <6278d2220811070543p51ca2139t13aba28e6dba5ff4@mail.gmail.com> References: <6278d2220811040632u7a36d68ekad5de517fd0671bb@mail.gmail.com> <20081105.151015.206163697.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE To: "Mikael Abrahamsson" , "David Miller" , LKML , Netdev , linux-net@vger.kernel.org, "=?ISO Return-path: In-Reply-To: Content-Disposition: inline Sender: linux-net-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Fri, Nov 7, 2008 at 12:22 PM, Ilpo J=E4rvinen wrote: > On Fri, 7 Nov 2008, Mikael Abrahamsson wrote: >> On Fri, 7 Nov 2008, Ilpo J=E4rvinen wrote: >> > I think you partially miss the point here. In many cases not every >> > single >> > router has to _support_ ECN to get its benefits, not-supporting is= not >> > the >> > problem in itself (though it would be nice to get that "fixed" as = well) >> > but >> > breaking ecn-enabled connections. I suppose you didn't check that >> > aspect? >> > I'd guess those mentioned devices will interoperate just fine sinc= e one >> > can >> > mostly connect ok with ecn too besides rare exceptions rather than >> > things >> > being vice-versa. >> >> I don't understand. My point is that most of the ISP core equipment = out >> there >> doesn't act on ECN rendering it mostly useless. The N in ECN renders >> useless >> because there is no device doing the *notification*. They'll just pa= ss the >> traffic without acting on it differently regardless if ECN is on or = off. I've been running with ECN enabled on all my client linux systems and (personal) webservers for the past 6 or so years. When I've encountered issues accessing particular hosts, I turn it and TCP window scaling off, but invariably it is always another cause. If most ECN-broken hardware is embedded consumer appliances (which are generally short-lifespan and moving more and more to linux), then we avoid hurting these users by enabling ECN per default when eg CONFIG_IP_ADVANCED_ROUTER is set (to little direct benefit of course). It's a start and a constructive idea; by doing this and documenting it, we provide a wake-up call for vendors, laying the path for enabling it for all types of host in a few years. Even enabling ECN for -rc kernels will raise awareness. Alternatively, an ECN-day could be publicised targeting the linux tech community, where we can report failing networks/sites to a central website to quantify actual potential negative impact. But doing nothing is cyclic - when will the natural break suddenly occu= r? --=20 Daniel J Blueman