Re: [aqm] [tcpm] ECN support and usage on the Internet

[Mikael Abrahamsson <[e-mail]>]

On Tue, 19 Mar 2013, Mirja Kühlewind wrote:

> Do we need to start a campaign to further encourage greater ECN support 
> (also of network providers)? Asking the content providers on the 
> list(s): What are the reasons to not enable ECN support?

Let me speculate:

It's not on by default in Windows. There is little reason to turn it on, 
because "nobody" acts on ECN, and nobody acts on ECN because there is no 
demand for AQM, and even if there was AQM, it would most likely not be ECN 
enabled.

I tried enabling ECN back in 2001 but saw major breakage. I re-enabled ECN 
again around 2008 or so <http://seclists.org/nanog/2008/Nov/250> and 
investigated, and at least the vendors I talked to didn't show much 
interest. I've been running with ECN on ever since and have not 
experienced any breakage I could trace back to ECN usage. This is hopeful.

I believe the Bufferbloat discussions and increased interest in AQM on the 
customer access link will increase interest in ECN as well, so the 
important thing is that AQM document includes requirements for AQM, so 
when I request support for "best practice AQM", I get ECN support as well. 
I am looking for RFC6204 (Basic Requirements) style document.

Then we need to advertise ECN benefit to end users, for instance by 
advocating its use through tools like 
<http://www.speedguide.net/tcpoptimizer.php>. The change log says "Changed 
ECN Capability optimal recommendation in General tab based on user 
feedback and issues with some US ISPs" and I fear that the recommendation 
there is to turn ECN off :P. I don't want to install the utility to test.

-- 
Mikael Abrahamsson    email: [e-mail]