From owner-freebsd-net Tue Aug 14 11:47:57 2001 Delivered-To: freebsd-net@freebsd.org Received: from neon-gw.transmeta.com (neon-gw-l3.transmeta.com [63.209.4.196]) by hub.freebsd.org (Postfix) with ESMTP id 11EC437B405 for ; Tue, 14 Aug 2001 11:47:54 -0700 (PDT) (envelope-from hpa@zytor.com) Received: (from root@localhost) by neon-gw.transmeta.com (8.9.3/8.9.3) id JAA31803; Tue, 14 Aug 2001 09:41:11 -0700 Received: from mailhost.transmeta.com(10.1.1.15) by neon-gw.transmeta.com via smap (V2.1) id xma031790; Tue, 14 Aug 01 09:40:56 -0700 Received: from tazenda.transmeta.com (tazenda.transmeta.com [10.8.42.16]) by deepthought.transmeta.com (8.9.3/8.9.3) with ESMTP id JAA09061; Tue, 14 Aug 2001 09:40:57 -0700 (PDT) Received: from zytor.com (hpa@localhost [127.0.0.1]) by tazenda.transmeta.com (8.9.3/8.7.3) with ESMTP id JAA00730; Tue, 14 Aug 2001 09:40:57 -0700 Message-ID: <3B795499.4050307@zytor.com> Date: Tue, 14 Aug 2001 09:40:57 -0700 From: "H. Peter Anvin" Organization: Zytor Communications User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:0.9.3) Gecko/20010801 X-Accept-Language: en, sv MIME-Version: 1.0 To: Gerhard Butscher Cc: syslinux@linux.kernel.org, net@FreeBSD.ORG Subject: Re: TFTP sorcerer's apprentice syndrome References: <3B78F5E1.475FF891@esk.fhg.de> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org Gerhard Butscher wrote: > Hello, > > I am using the linux (SuSE 7.0) tftp server with an embedded > tftp client (running on an embedded target). I changed that > client code and caused by that change a considerable amount of > delay. And the Sorcerer's Apprentice Syndrome appeared: > >>From that point where the server has sent a duplicate data > packet (after the client's ACK timed out), there were always > duplicate data (and of course ACK) packets until the end > of the file transfer. > > I am not a protocol expert nor a unix programming expert > but as far as I understand the tftp server code (e.g. > tftp-hpa-0.21) there is a handling for duplicate ACK packets. > But (maybe) not exactly the handling proposed by the RFC 1350. > It's hard to know if this really is Sorcerer's Apprentice without seeing a trace of the traffic. There are other pathologies that can cause this. Besides, you're talking about the "SuSE 7.0 tftp server", which definitely isn't tftp-hpa-0.21, so I don't know what baseline code you're talking about. -hpa To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message