netdev - Re: [PATCH net-next] tcp: be more strict before accepting ECN negociation

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Message-ID: <4FA41B5B.5080103@hp.com>
Date:	Fri, 04 May 2012 11:09:31 -0700
From:	Rick Jones <rick.jones2@...com>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>,
	Perry Lorier <perryl@...gle.com>,
	Matt Mathis <mattmathis@...gle.com>,
	Yuchung Cheng <ycheng@...gle.com>,
	Neal Cardwell <ncardwell@...gle.com>,
	Tom Herbert <therbert@...gle.com>,
	Wilmer van der Gaast <wilmer@...gle.com>,
	Dave Täht <dave.taht@...ferbloat.net>,
	Ankur Jain <jankur@...gle.com>
Subject: Re: [PATCH net-next] tcp: be more strict before accepting ECN negociation

On 05/04/2012 08:14 AM, Eric Dumazet wrote:
> From: Eric Dumazet<edumazet@...gle.com>
>
> It appears some networks play bad games with the two bits reserved for
> ECN. This can trigger false congestion notifications and very slow
> transferts.
>
> Since RFC 3168 (6.1.1) forbids SYN packets to carry CT bits, we can
> disable TCP ECN negociation if it happens we receive mangled CT bits in
> the SYN packet.

What sort of networks were these?  Any chance it was some sort of 
attempt to add ECN to FastOpen?

rick jones

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