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Cc: Juliusz Chroboczek <jch@pps.jussieu.fr>, codel@lists.bufferbloat.net,
	bloat@lists.bufferbloat.net
Subject: Re: [Codel] [Bloat] better tc support for bittorrent/diffserv
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On 05/14/2012 11:03 AM, Eric Dumazet wrote:
> On Mon, 2012-05-14 at 19:50 +0200, Juliusz Chroboczek wrote:
>> [Pro memoria, I'm the author of a few of the networking bits in
>> Transmission, notably the DHT, the µTP support and large parts of the
>> IPv6 code.]
>>
>>> 0) No ecn on transmission, at least.
>> TCP flows will use ECN if your system is configured to use ECN.  µTP
>> doesn't do ECN, and there's no easy way to implement it -- there's no
>> API to set ECN on UDP packets.
> There is an API to set ECN on UDP packets.
>
> setsockopt() IP_TOS, with val = 2

I think, but am not certain, jch is referring to the problem of 
negotiating ecn over uTP.

I'd like it if it could, as a background protocol it could then give us 
some statistics as to the actual success rate of passing it, and if it 
fails to work right, fall back into a more 'happy eyeballs' scenario.