From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ip-64-139-1-69.sjc.megapath.net (ip-64-139-1-69.sjc.megapath.net [64.139.1.69]) by huchra.bufferbloat.net (Postfix) with ESMTP id 3D14521F2A6 for ; Mon, 12 May 2014 21:33:29 -0700 (PDT) Received: from shuksan (localhost [127.0.0.1]) by ip-64-139-1-69.sjc.megapath.net (Postfix) with ESMTP id 63233406060; Mon, 12 May 2014 21:33:28 -0700 (PDT) X-Mailer: exmh version 2.7.2 01/07/2005 with nmh-1.3 To: bloat@lists.bufferbloat.net From: Hal Murray Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Mon, 12 May 2014 21:33:28 -0700 Message-Id: <20140513043328.63233406060@ip-64-139-1-69.sjc.megapath.net> Cc: Hal Murray Subject: Re: [Bloat] How is bufferbloat prevented/fixed for UDP? 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: Tue, 13 May 2014 04:33:29 -0000 > 1)With UDP, you cannot uniquely identify a flow? This prevents an > AQM-algorithm to drop packets for an (several) offending UDP flow(s). UDP packets have port numbers, just like TCP. > 2) Unlike TCP, UDP does not back down when encountering packet loss Mumble. The OS doesn't do it. It has to be done in user code. But there is no reason that it can't be done there even if it isn't done correctly as often as we might like. I think most DNS code is reasonably sane, mostly because the retransmit timeout is several seconds and also because it only retransmits a few times. The poster child for how to do it wrong is the NTP client that was shipped in a zillion Netgear home routers with a hard wired NTP server. Dave Plonka did a wonderful writeup. http://pages.cs.wisc.edu/~plonka/netgear-sntp/ I call it required reading (and understanding) for anybody interested in networks. -- These are my opinions. I hate spam.