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Message-ID: <1336158359.3752.382.camel@edumazet-glaptop> Date: Fri, 04 May 2012 21:05:59 +0200 From: Eric Dumazet <eric.dumazet@...il.com> To: Rick Jones <rick.jones2@...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 Fri, 2012-05-04 at 11:48 -0700, Rick Jones wrote: > On 05/04/2012 11:23 AM, Eric Dumazet wrote: > > On Fri, 2012-05-04 at 11:09 -0700, Rick Jones wrote: > >> What sort of networks were these? Any chance it was some sort of > >> attempt to add ECN to FastOpen? > > > > Nothing to do with fastopen. > > > > Just take a look at a random http server and sample all SYN packets it > > receives. > > > > Some of them have TOS bits 0 or 1 set, or even both bits set. > > I'll fire-up tcpdump on netperf.org: > > tcpdump -i eth0 -vvv '(tcp[tcpflags] & tcp-syn != 0) && (ip[1] != 0x0)' > > and see what appears. > > rick of (ip[1] & 3 != 0) Note that you could catch SYNACK with this filter (if your machine initiates some active TCP sessions), since SYNACK might have ECT bits, if some stacks implemented : http://tools.ietf.org/html/draft-kuzmanovic-ecn-syn-00 ( Adding Explicit Congestion Notification (ECN) Capability to TCP's SYN/ACK Packets ) http://tools.ietf.org/id/draft-ietf-tcpm-ecnsyn-04.txt -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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