From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mailgw1.uni-kl.de (mailgw1.uni-kl.de [IPv6:2001:638:208:120::220]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 359353B29D for ; Sun, 23 May 2021 14:47:44 -0400 (EDT) Received: from [172.20.10.2] (dynamic-046-114-003-126.46.114.pool.telefonica.de [46.114.3.126]) (authenticated bits=0) by mailgw1.uni-kl.de (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id 14NIlVa1171086 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT) for ; Sun, 23 May 2021 20:47:41 +0200 To: bloat@lists.bufferbloat.net References: <7FBA3F6F-CBA1-4B19-B48F-10927EDA17A9@gmail.com> From: Erik Auerswald Message-ID: Date: Sun, 23 May 2021 20:47:29 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <7FBA3F6F-CBA1-4B19-B48F-10927EDA17A9@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit X-Spam-Status: No, hits=0.399, tests=KHOP_HELO_FCRDNS=0.4,NICE_REPLY_A=-0.001 X-Spam-Score: (0.399) X-Spam-Flag: NO Subject: Re: [Bloat] Educate colleges on tcp vs udp 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, 23 May 2021 18:47:44 -0000 Hi, On 23.05.21 12:23, Jonathan Morton wrote: >> On 21 May, 2021, at 9:01 am, Taraldsen Erik wrote: >> >> I'm getting some traction with my colleges in the Mobile department on measurements to to say something about user experience. While they are coming around to the idea, they have major gaps in tcp/udp/ip understanding. I don't have the skill or will to try and educate them. >> [...] > > I don't have a video link to hand, but let's tease out the major differences between these three protocols: > [...] > It's common to use UDP for simple request-response applications (where both the request and response are small) and where timeliness of delivery is far more important than reliability (eg. multiplayer games, voice/video calls). As an additional point to consider when pondering whether to use TCP or UDP: To mitigate that simple request-response protocols using UDP lend themselves to being abused for reflection and amplification (DDoS) attacks, either the response should be smaller than the request, or the protocol should require authentication, with either silent discard of packets that are not correctly authenticated, or at least a smaller error message (with rate limit, please) to indicate an authentication failure. Especially if the response needs to be larger than the request, e.g., with DNS, a response rate limit should be applied. Since basic TCP first establishes a connection using small packets (SYN, SYN+ACK, ACK), it is less useful for reflection attacks than UDP. Thanks, Erik