From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cassarossa.samfundet.no (cassarossa.samfundet.no [IPv6:2001:67c:29f4::29]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 566443B2B0 for ; Sun, 12 Jun 2016 17:24:43 -0400 (EDT) Received: from pannekake.samfundet.no ([2001:67c:29f4::50] ident=unknown) by cassarossa with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.84_2) (envelope-from ) id 1bCCs4-0003ql-Ii for bloat@lists.bufferbloat.net; Sun, 12 Jun 2016 23:24:40 +0200 Received: from sesse by pannekake.samfundet.no with local (Exim 4.84_2) (envelope-from ) id 1bCCs4-0008TY-GT for bloat@lists.bufferbloat.net; Sun, 12 Jun 2016 23:24:40 +0200 Date: Sun, 12 Jun 2016 23:24:40 +0200 From: "Steinar H. Gunderson" To: bloat@lists.bufferbloat.net Message-ID: <20160612212440.GB25090@sesse.net> References: <151299a8-87ec-6a8a-b44b-9f710c31a46f@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-Operating-System: Linux 4.7.0-rc1 on a x86_64 User-Agent: Mutt/1.5.23 (2014-03-12) Subject: Re: [Bloat] Questions About Switch Buffering X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 12 Jun 2016 21:24:43 -0000 On Sun, Jun 12, 2016 at 01:25:17PM -0500, Benjamin Cronce wrote: > Internal networks rarely have bandwidth issues and congestion only happens > when you don't have enough bandwidth. I don't think this is true. You might not have an aggregate bandwidth issues, but given the burstiness of TCP and the typical switch buffer depth (64 frames is a typical number), it's very very easy to lose packets in your switch even on a relatively quiet network with no downconversion. (Witness the rise of DCTCP, made especially for internal traffic on this kind of network.) /* Steinar */ -- Homepage: https://www.sesse.net/