From: Rick Jones <rick.jones2@hp.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: "David Miller" <davem@davemloft.net>,
netdev <netdev@vger.kernel.org>,
"Perry Lorier" <perryl@google.com>,
"Matt Mathis" <mattmathis@google.com>,
"Yuchung Cheng" <ycheng@google.com>,
"Neal Cardwell" <ncardwell@google.com>,
"Tom Herbert" <therbert@google.com>,
"Wilmer van der Gaast" <wilmer@google.com>,
"Dave Täht" <dave.taht@bufferbloat.net>,
"Ankur Jain" <jankur@google.com>
Subject: Re: [PATCH net-next] tcp: be more strict before accepting ECN negociation
Date: Fri, 04 May 2012 13:20:19 -0700 [thread overview]
Message-ID: <4FA43A03.4090707@hp.com> (raw)
In-Reply-To: <1336158359.3752.382.camel@edumazet-glaptop>
On 05/04/2012 12:05 PM, Eric Dumazet wrote:
> On Fri, 2012-05-04 at 11:48 -0700, Rick Jones wrote:
>> 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)
True, I'm looking at more than the ECN bits, but in the 90 minutes the
tcpdump has been running there have been no packets with the any of the
8 bits at ip[1] being 1 anyway :) Netperf.org doesn't get a massive
quantity of traffic. It may go the entire week-end or longer without
seeing such a packet.
> 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
True. I suspect that 99 times out of 10, the outbound connections
established by netperf.org are in response to traffic to netperf-talk,
which is itself a rather quiet list, so I'm not too worried about the
output being cluttered with false hits.
rick
next prev parent reply other threads:[~2012-05-04 20:20 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-04 15:14 [PATCH net-next] tcp: be more strict before accepting ECN negociation Eric Dumazet
2012-05-04 15:54 ` Neal Cardwell
2012-05-04 16:06 ` David Miller
2012-05-04 18:09 ` Rick Jones
2012-05-04 18:23 ` Eric Dumazet
2012-05-04 18:48 ` Rick Jones
2012-05-04 19:05 ` Eric Dumazet
2012-05-04 20:20 ` Rick Jones [this message]
2012-05-04 20:36 ` Rick Jones
2012-05-04 20:49 ` Eric Dumazet
2012-05-04 21:01 ` Rick Jones
2012-05-04 21:14 ` Eric Dumazet
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