From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=5.0 tests=MAILING_LIST_MULTI, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 22207 invoked from network); 25 Jun 2022 23:09:50 -0000 Received: from minnie.tuhs.org (50.116.15.146) by inbox.vuxu.org with ESMTPUTF8; 25 Jun 2022 23:09:50 -0000 Received: from minnie.tuhs.org (localhost [IPv6:::1]) by minnie.tuhs.org (Postfix) with ESMTP id 43CC94068D; Sun, 26 Jun 2022 09:09:46 +1000 (AEST) Received: from mcvoy.com (mcvoy.com [192.169.23.250]) by minnie.tuhs.org (Postfix) with ESMTPS id 8C9834013A for ; Sun, 26 Jun 2022 09:09:40 +1000 (AEST) Received: by mcvoy.com (Postfix, from userid 3546) id 07D9935E847; Sat, 25 Jun 2022 16:09:39 -0700 (PDT) Date: Sat, 25 Jun 2022 16:09:39 -0700 From: Larry McVoy To: Paul Ruizendaal Message-ID: <20220625230939.GG19404@mcvoy.com> References: <2803DC51-6CBC-4257-B40C-8A559C27CAE3@planet.nl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2803DC51-6CBC-4257-B40C-8A559C27CAE3@planet.nl> User-Agent: Mutt/1.5.24 (2015-08-30) Message-ID-Hash: VXEDEL4R3ZFYEH6PQR4QCOWCWNU3OAJC X-Message-ID-Hash: VXEDEL4R3ZFYEH6PQR4QCOWCWNU3OAJC X-MailFrom: lm@mcvoy.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-tuhs.tuhs.org-0; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: tuhs@tuhs.org X-Mailman-Version: 3.3.6b1 Precedence: list Subject: [TUHS] Re: Research Datakit notes List-Id: The Unix Heritage Society mailing list Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: Nice. Any chance you want to do a TCP/XTP comparison? On Sun, Jun 26, 2022 at 01:01:07AM +0200, Paul Ruizendaal wrote: > Wanted to post my notes as plain text, but the bullets / sub-bullets get lost. > > Here is a 2 page PDF with my notes on Research Datakit: > > https://www.jslite.net/notes/rdk.pdf > > The main takeaway is that connection build-up and tear-down is considerably more expensive than with TCP. The first cost is in the network, which builds up a dedicated path for each connection. Bandwidth is not allocated/reserved, but a path is and routing information is set up at each hop. The other cost is in the relatively verbose switch-host communication in this phase. This compares to the 3 packets exchanged at the hosts??? driver level to set up a TCP connection, with no permanent resources consumed in the network. > > In compensation, the cost to use a connection is considerably lower: the routing is known and the host-host link protocol (???URP") can be light-weight, as the network guarantees in-order delivery without duplicates but packets may be corrupted or lost (i.e. as if the connection is a phone line with a modem). No need to deal with packet fragmentation, stream reassembly and congestion storms as in the TCP of the early 80???s. > > Doing UDP traffic to a fixed remote host is easily mapped to using URP with no error correction and no flow control. Doing UDP where the remote host is different all the time is not practical on a Datakit network (i.e. a virtual circuit would be set up anyway). > > A secondary takeaway is that Research Datakit eventually settled on a three-level ascii namespace: ???area/trunk/switch???. On each switch, the hosts would be known by name, and each connection request had a service name as parameter. In an alternate reality we would maybe have used ???ca/stclara/mtnview!google!www??? to do a search. -- --- Larry McVoy Retired to fishing http://www.mcvoy.com/lm/boat