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Date: Mon, 18 May 2015 07:46:34 +0200 (CEST)
From: Mikael Abrahamsson <swmike@swm.pp.se>
To: Kevin Darbyshire-Bryant <kevin@darbyshire-bryant.me.uk>
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Cc: bloat <bloat@lists.bufferbloat.net>
Subject: Re: [Bloat] tc -s qdisc questions
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On Sun, 17 May 2015, Kevin Darbyshire-Bryant wrote:

> Thanks Mikael - some ECN tweakage in progress.  I'll see which bits of 
> the Internet I use break :-)

I have been running this on my macbook for almost 2 years (since I got 
it):

$ cat /etc/sysctl.conf
net.inet.tcp.ecn_initiate_out=1
net.inet.tcp.ecn_negotiate_in=1

and this on my linux server for 5+ years:

$ cat /etc/sysctl.conf | grep -i ecn
net.ipv4.tcp_ecn = 1

I used the same on my previous Ubuntu based laptop for 5+ years.

I have yet to encounter any ECN related breakage. I have had significant 
problems with IPv6 PMTUD blackholing, but no ECN related problems. I had 
ECN related problems back in 2001 (or whenever it was)  when Linux first 
introduced it due to a lot of firewalls being very paranoid about it, but 
then I turned it back on again 5-7 years ago and by then all problems were 
gone.

-- 
Mikael Abrahamsson    email: swmike@swm.pp.se