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 412393CB35 for ; Mon, 24 May 2021 14:51:25 -0400 (EDT) Received: from [172.20.10.2] (x52716277.dyn.telefonica.de [82.113.98.119]) (authenticated bits=0) by mailgw1.uni-kl.de (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id 14OIpA1u172559 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 24 May 2021 20:51:21 +0200 To: Taraldsen Erik , bloat References: From: Erik Auerswald Message-ID: Date: Mon, 24 May 2021 20:51:07 +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: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit X-Spam-Status: No, hits=1.839, tests=KHOP_HELO_FCRDNS=0.399, NICE_REPLY_A=-0.001, URI_DOTEDU=1.441 X-Spam-Score: * (1.839) 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: Mon, 24 May 2021 18:51:25 -0000 Hi Erik, On 21.05.21 08:01, 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. > > > Is there good education out there - preferably in the form of an video - which I can send to my co workers? The part of tcp using ack's is pure magic to them. They really struggle to grasp the concept. With so basic lack of understanding it is hard to have a meaningful discussion about loss, latency an buffering. You could take a look at: "Video Notes: Tanenbaum, Wetherall Computer Networks 5e" https://media.pearsoncmg.com/ph/streaming/esm/tanenbaum5e_videonotes/tanenbaum_videoNotes.html Specifically the sections "Transport Layer, Reliable Transport" and "Congestion Control." For reading material I can recommend "The TCP/IP Guide" http://www.tcpipguide.com/ . You can find a curated list of freely available networking (i.e., packet switching and TCP/IP) textbooks in the section "Textbooks and Other Books You Should Read" of the "How Networks Really Work" webinars from Ivan Pepelnjak: https://my.ipspace.net/bin/list?id=Net101#TEXTBOOK > I don't mean to talk them down to much, they are really good with the radio part of their job - but the transition into seeing tcp and radio together is very hard on them. Packet switching, and the transport services built on top, e.g., TCP, are different from other information transport systems. They have evolved over decades and have become quite complex, with surprising interactions (e.g., bufferbloat). IP data over mobile networks is even more complex, and it differs for the different mobile network generations. Thus I do not think one should expect to really understand it immediately. Jumping right into the middle with TCP ACKs, used for both reliability and flow control, and as part of the congestion control scheme used on the Internet, without looking at the fundamentals first, seems quite hard. My advice, if I may, would be to view IP/TCP as something new to your colleagues. It would seem advisable to me to start by learning the fundamentals. This would most probably require quite some time, though. After achieving some confidence regarding the fundamentals, I recommend taking a look at the four links from: https://www.unix-ag.uni-kl.de/~auerswal/networkers_essential_reading/ (especially the paper "End-to-End Arguments in System Design" http://web.mit.edu/Saltzer/www/publications/endtoend/endtoend.pdf). HTH, Erik