From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bifrost.lang.hm (mail.lang.hm [64.81.33.126]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by huchra.bufferbloat.net (Postfix) with ESMTPS id 8463221F285 for ; Tue, 17 Mar 2015 12:30:40 -0700 (PDT) Received: from asgard.lang.hm (asgard.lang.hm [10.0.0.100]) by bifrost.lang.hm (8.13.4/8.13.4/Debian-3) with ESMTP id t2HJUb4g029989; Tue, 17 Mar 2015 11:30:37 -0800 Date: Tue, 17 Mar 2015 12:30:37 -0700 (PDT) From: David Lang X-X-Sender: dlang@asgard.lang.hm To: Dave Taht In-Reply-To: Message-ID: References: <7i1tkozwf2.wl-jch@pps.univ-paris-diderot.fr> <87pp87x2yp.wl-jch@pps.univ-paris-diderot.fr> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/Plain; format=flowed; charset=US-ASCII Cc: "cerowrt-devel@lists.bufferbloat.net" Subject: Re: [Cerowrt-devel] Fwd: Dave's wishlist [was: Source-specific routing merged] X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 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: Tue, 17 Mar 2015 19:31:09 -0000 On Tue, 17 Mar 2015, Dave Taht wrote: > My quest is always for an extra "9" of reliability. Anyplace where you can > make something more robust (even if it is out at the .9999999999) level, I > tend to like to do in order to have the highest MTBF possible in > combination with all the other moving parts on the spacecraft (spaceship > earth). There are different ways to add reliability one is to try and make sure nothing ever fails the second is to have a way of recovering when things go wrong. Bufferbloat came about because people got trapped into the first mode of thinking (packets should never get lost), when the right answer ended up being to realize that we have a recovery method and use it. Sometimes trying to make sure nothing ever fails adds a lot of complexity to the code to handle all the corner cases, and the overall reliability will improve by instead simplify normal flow, even if it add a small number of failures, if that means that you can have a common set of recovery code that's well excercised and tested. As you are talking about loosing packets with route changes, watch out that you don't fall into this trap. David Lang