From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail2.tohojo.dk (mail2.tohojo.dk [77.235.48.147]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 0489A3B260 for ; Mon, 6 Jun 2016 12:53:27 -0400 (EDT) X-Virus-Scanned: amavisd-new at mail2.tohojo.dk DKIM-Filter: OpenDKIM Filter v2.10.3 mail2.tohojo.dk 1730C40472 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=toke.dk; s=201310; t=1465232005; bh=8dtqp9I6LEJBkf1GqX9joNvdRYyqGRiTfSC7wdsPLLc=; h=From:To:Cc:Subject:References:Date:In-Reply-To:From; b=gXwssI/NNkmK7JocO4rcyZfIPv5QF8yFJrHQE8H9HKDZghbkJ57ws57BV2DOQ1WiK sxJujJkxLVZskPIFKJTOF9A+cPTAvp6VRAly+OENWM6oso7OAdgxhEGHD1+O8LLRIz Hxhja7XL+FelSFqdkZZ/rhMJpJrftdxkUMyuaIx4= Sender: toke@toke.dk Received: by alrua-karlstad.karlstad.toke.dk (Postfix, from userid 1000) id 18C0D75995A; Mon, 6 Jun 2016 18:53:23 +0200 (CEST) From: =?utf-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= To: Eric Johansson Cc: "cerowrt-devel\@lists.bufferbloat.net" References: <55fdf513-9c54-bea9-1f53-fe2c5229d7ba@eggo.org> Date: Mon, 06 Jun 2016 18:53:22 +0200 In-Reply-To: <55fdf513-9c54-bea9-1f53-fe2c5229d7ba@eggo.org> (Eric Johansson's message of "Mon, 6 Jun 2016 11:29:38 -0400") X-Clacks-Overhead: GNU Terry Pratchett Message-ID: <871t4as1h9.fsf@toke.dk> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Cerowrt-devel] trying to make sense of what switch vendors say wrt buffer bloat X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 06 Jun 2016 16:53:28 -0000 Eric Johansson writes: > Buffer bloat was a relevant on 10/100M switches, not 10Gb switches. At > 10Gb we can empty the queue in ~100ms, which is less than the TCP > retransmission timers, therefore no bloat. Buffer bloat can happen at > slower speeds, but not an issue at the speeds we have on our switches. 100 ms of buffering at 10 Gbps? Holy cow! There's no agreed-upon definition of what exactly constitutes 'bloat', and it really depends on the application. As such, I'm not surprised that this is the kind of answer you get if you ask "do your switches suffer from bufferbloat". A better question would be "how much buffer latency can your switches add to my traffic" - which they offer here. If I read the answer right, anytime you have (say) two ingress ports sending traffic at full speed out one egress port, that traffic will be queued for 100 ms. I would certainly consider that broken, but well, YMMV depending on what you need them for... -Toke