From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-02-iad.dyndns.com (mxout-214-iad.mailhop.org [216.146.32.214]) by lists.bufferbloat.net (Postfix) with ESMTP id 922882E0438 for ; Thu, 10 Feb 2011 09:50:10 -0800 (PST) Received: from scan-01-iad.mailhop.org (scan-01-iad.local [10.150.0.206]) by mail-02-iad.dyndns.com (Postfix) with ESMTP id 89BB9835B80 for ; Thu, 10 Feb 2011 17:50:10 +0000 (UTC) X-Spam-Score: 0.1 () X-Mail-Handler: MailHop by DynDNS X-Originating-IP: 75.145.127.229 Received: from gw.co.teklibre.org (75-145-127-229-Colorado.hfc.comcastbusiness.net [75.145.127.229]) by mail-02-iad.dyndns.com (Postfix) with ESMTP id 05A688357E4 for ; Thu, 10 Feb 2011 17:50:07 +0000 (UTC) Received: from cruithne.co.teklibre.org (unknown [IPv6:2002:4b91:7fe5:1::20]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "cruithne.co.teklibre.org", Issuer "CA Cert Signing Authority" (verified OK)) by gw.co.teklibre.org (Postfix) with ESMTPS id BFF325EC57 for ; Thu, 10 Feb 2011 10:50:05 -0700 (MST) Received: by cruithne.co.teklibre.org (Postfix, from userid 1000) id 185BD121FA8; Thu, 10 Feb 2011 10:50:04 -0700 (MST) From: d@taht.net (Dave =?utf-8?Q?T=C3=A4ht?=) To: Jim Gettys Organization: Teklibre - http://www.teklibre.com References: <20110205132305.GA29396@thyrsus.com> <20110208181811.GD7744@thyrsus.com> <4D53FC4B.5000307@freedesktop.org> Date: Thu, 10 Feb 2011 10:50:04 -0700 In-Reply-To: <4D53FC4B.5000307@freedesktop.org> (Jim Gettys's message of "Thu, 10 Feb 2011 09:55:07 -0500") Message-ID: <87lj1n3hkj.fsf@cruithne.co.teklibre.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: bloat@lists.bufferbloat.net Subject: Re: [Bloat] First draft of complete "Bufferbloat And You" enclosed. X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 10 Feb 2011 17:50:11 -0000 Jim Gettys writes: > Well, another way to think about transport protocols is as servo > systems, that apply feedback to control the rates. > > If you look at the TCP traces that set me off on this merry chase, you > see quite violent periodic behaviour, where the periods are quite long > (of order 10 seconds). > > Injecting delays way beyond the natural RTT is hazardous to the > stability of transport protocols. > > You can see TCP slowly losing its mind it's RTT estimation gets longer > and longer as the buffer fills. Eventually, it goes ballistic. > > The servo system's stability has been destroyed... I LIKE the idea of trying to think about this as a complex servo system. I also like many of the other analogies that have gone by. At the moment, the lower levels of plumbing in the internet's servos more closely resemble a rube goldberg machine. Everybody here could use a belly laugh. Try this: http://www.youtube.com/watch?v=qybUFnY7Y8w We've also been overcomplicating this discussion, getting overwhelmed in detail. There is no perfect analogy, all we can do is - as blind men feeling up this elephant from trunk, hip and tail - is to keep trying to describe its shape in as many different ways as possible until it's more than a shadow on the wall... [1] If we can take a step back and not go for one-size-fits all and think of each audience that we need to address, perhaps we'll keep finding analogies that work for each audience in smaller, more digestible, pieces. > - Jim > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat [1] Plato and the Elephant - coming soon to a writers workshop near you! -- Dave Taht http://nex-6.taht.net