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=-0.8 required=5.0 tests=DKIM_INVALID,DKIM_SIGNED, MAILING_LIST_MULTI,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 20876 invoked from network); 25 Jun 2022 23:02:00 -0000 Received: from minnie.tuhs.org (50.116.15.146) by inbox.vuxu.org with ESMTPUTF8; 25 Jun 2022 23:02:00 -0000 Received: from minnie.tuhs.org (localhost [IPv6:::1]) by minnie.tuhs.org (Postfix) with ESMTP id 228094012F; Sun, 26 Jun 2022 09:01:36 +1000 (AEST) Received: from ewsoutbound.kpnmail.nl (unknown [195.121.94.170]) by minnie.tuhs.org (Postfix) with ESMTPS id 3F23140121 for ; Sun, 26 Jun 2022 09:01:20 +1000 (AEST) X-KPN-MessageId: ac6863c5-f4da-11ec-8294-005056ab378f Received: from smtp.kpnmail.nl (unknown [10.31.155.38]) by ewsoutbound.so.kpn.org (Halon) with ESMTPS id ac6863c5-f4da-11ec-8294-005056ab378f; Sun, 26 Jun 2022 01:00:57 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=planet.nl; s=planet01; h=to:date:message-id:subject:mime-version:content-type:from; bh=bVCQPlq+Sxc7gRP96uegHxzPxGUSuySYR/FSLhSXzvg=; b=HnDYSsnFl4nWEuT9LfNIQuxjmaAJ7tQ+J8n9ejCYgJtW8JdO0RaNdHmXfseW+xH2cSezPnlqieW64 fxqB4SMz+DUtwQZviZ+cM4kIUYDMtzh7cbpGzbJwO4nFhQeKDWOgHzpcgSpDF6bWMWt+mDRJiH4emf Tz+1D0bz4XVr8V/o= X-KPN-MID: 33|tqV58LldClZ0q4zpDI2GVBasHfV/SenzOGXm0hh100pGXeXatd2Mi0UfaIVPdc+ nVaUXBlMLa88+gfVgVySxrQ== X-KPN-VerifiedSender: Yes X-CMASSUN: 33|8Qxmj8qU/edoKI65XsQqHBDxysVxCrnU8qW4vMiwVZRRlaD9/AJRBbkE4IDSFRe QbNojQXRu+qAcyC35/glAhw== X-Originating-IP: 77.172.38.96 Received: from smtpclient.apple (77-172-38-96.fixed.kpn.net [77.172.38.96]) by smtp.kpnmail.nl (Halon) with ESMTPSA id b2c77f99-f4da-11ec-b5e4-005056abf0db; Sun, 26 Jun 2022 01:01:08 +0200 (CEST) From: Paul Ruizendaal Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Mime-Version: 1.0 (Mac OS X Mail 14.0 \(3654.120.0.1.13\)) Message-Id: <2803DC51-6CBC-4257-B40C-8A559C27CAE3@planet.nl> Date: Sun, 26 Jun 2022 01:01:07 +0200 To: tuhs@tuhs.org X-Mailer: Apple Mail (2.3654.120.0.1.13) Message-ID-Hash: ECHFLWSZYH2E5IRFFS6YFKFYUJMALT27 X-Message-ID-Hash: ECHFLWSZYH2E5IRFFS6YFKFYUJMALT27 X-MailFrom: pnr@planet.nl 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 X-Mailman-Version: 3.3.6b1 Precedence: list Subject: [TUHS] 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: 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=E2=80=99 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 (=E2=80=9CURP") 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=E2=80=99s. 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: =E2=80=9Carea/trunk/switch=E2=80=9D. 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 =E2=80=9Cca/stclara/mtnview!google!www=E2=80=9D to = do a search.=