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From: David Miller <davem@davemloft.net>
To: olivier.tilmans@nokia-bell-labs.com
Cc: research@bobbriscoe.net, koen.de_schepper@nokia-bell-labs.com,
	edumazet@google.com, kuznet@ms2.inr.ac.ru,
	yoshfuji@linux-ipv6.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next] tcp: Accept ECT on SYN in the presence of RFC8311
Date: Thu, 04 Apr 2019 17:44:19 -0700 (PDT)	[thread overview]
Message-ID: <20190404.174419.1813732301965311345.davem@davemloft.net> (raw)
In-Reply-To: <20190403134915.6616-1-olivier.tilmans@nokia-bell-labs.com>

From: "Tilmans, Olivier (Nokia - BE/Antwerp)" <olivier.tilmans@nokia-bell-labs.com>
Date: Wed, 3 Apr 2019 13:49:42 +0000

> Linux currently disable ECN for incoming connections when the SYN
> requests ECN and the IP header has ECT(0)/ECT(1) set, as some
> networks were reportedly mangling the ToS byte, hence could later
> trigger false congestion notifications.
> 
> RFC8311 §4.3 relaxes RFC3168's requirements such that ECT can be set
> one TCP control packets (including SYNs). The main benefit of this
> is the decreased probability of losing a SYN in a congested
> ECN-capable network (i.e., it avoids the initial 1s timeout).
> Additionally, this allows the development of newer TCP extensions,
> such as AccECN.
> 
> This patch relaxes the previous check, by enabling ECN on incoming
> connections using SYN+ECT if at least one bit of the reserved flags
> of the TCP header is set. Such bit would indicate that the sender of
> the SYN is using a newer TCP feature than what the host implements,
> such as AccECN, and is thus implementing RFC8311. This enables
> end-hosts not supporting such extensions to still negociate ECN, and
> to have some of the benefits of using ECN on control packets.
> 
> Signed-off-by: Olivier Tilmans <olivier.tilmans@nokia-bell-labs.com>
> Suggested-by: Bob Briscoe <research@bobbriscoe.net>

Applied, thanks.

      parent reply	other threads:[~2019-04-05  0:44 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-03 13:49 [PATCH net-next] tcp: Accept ECT on SYN in the presence of RFC8311 Tilmans, Olivier (Nokia - BE/Antwerp)
2019-04-03 14:14 ` Eric Dumazet
2019-04-03 15:39 ` Neal Cardwell
2019-04-03 15:51   ` Yuchung Cheng
2019-04-05  0:44 ` David Miller [this message]

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