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=-0.3 required=5.0 tests=DKIM_INVALID,DKIM_SIGNED, MAILING_LIST_MULTI,SUBJ_ALL_CAPS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 22534 invoked from network); 15 Jul 2022 11:56:18 -0000 Received: from minnie.tuhs.org (50.116.15.146) by inbox.vuxu.org with ESMTPUTF8; 15 Jul 2022 11:56:18 -0000 Received: from minnie.tuhs.org (localhost [IPv6:::1]) by minnie.tuhs.org (Postfix) with ESMTP id 55DAF406FD; Fri, 15 Jul 2022 21:55:44 +1000 (AEST) Received: from out5-smtp.messagingengine.com (out5-smtp.messagingengine.com [66.111.4.29]) by minnie.tuhs.org (Postfix) with ESMTPS id 11A72406F2 for ; Fri, 15 Jul 2022 21:55:40 +1000 (AEST) Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by mailout.nyi.internal (Postfix) with ESMTP id 1DA965C02CD for ; Fri, 15 Jul 2022 07:55:39 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute3.internal (MEProxy); Fri, 15 Jul 2022 07:55:39 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ronnatalie.com; h=cc:content-transfer-encoding:content-type:date:date:from:from :in-reply-to:in-reply-to:message-id:mime-version:references :reply-to:reply-to:sender:subject:subject:to:to; s=fm2; t= 1657886139; x=1657972539; bh=QLJMWahmW641NjWk7ZMN78Z3Oxt2vxBWg7y 2l9gelMo=; b=MdXFWPH8VA1pqbs4gYkhOq+LE+Jjvw7k6XoCuMljrFtxfwj+4/M g09HMrNxV/B80Pu+4sqQE8aWKPguJ+ZkEfRIikBG+Go8fdRQTqkOEvoLuUJm6jVv CfjULPJYbUPbgB+ZZC4bKz3nhrEcuLx7xtRFuVj8rhOWL8leTN18WYNOW1R+42+5 vpLkjkta3miz085aUv1h6AJn7PbYh4j2etO2Hbt4JkgMbspc1xift1Xfln4o/UKs 1CdFLWbQJCc9RrYO/RjVKA3Rgq8ufykpE7mK1HpzHxieUVYebY3MRVQyN/jKWQXo xRKlIGT4mFLa+D6unMvtKRbXM0PDE6wCe3g== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:date:feedback-id:feedback-id:from:from:in-reply-to :in-reply-to:message-id:mime-version:references:reply-to :reply-to:sender:subject:subject:to:to:x-me-proxy:x-me-proxy :x-me-sender:x-me-sender:x-sasl-enc; s=fm3; t=1657886139; x= 1657972539; bh=QLJMWahmW641NjWk7ZMN78Z3Oxt2vxBWg7y2l9gelMo=; b=i me2jtE+EuCgwmSFkUCor5j68oQDMOk5Az3/tcR1UsvfiNFVBwDdCferp/zhJNWa4 ++SuPL3NJcf/IJa9ZGVx1Moml8BdK4u0lDqZlpvmHLDn+QmG9z92gv5DVZisvdQP 6dPzCPrHFT8x2fmNgQ9j2s2UKkscWy6sP325ThfJoIEl7/NIKeVxQ9LLQcROTGoz /fNLWp3vwblMIxrORWVHebVg8v5Y4Z/0y23ARg/HCWX3rzsrT2Nh6qdBkdsSUheN DzazH07WRpvej7JDQnkumqf+TFzDDkaqlpQjfZJ6745sagWQXLc8tk6ckp4OeF/g N0PYlOlUfH0oYlIRuLqCA== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvfedrudekuddggeejucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucenucfjughrpefhvffufffkjghfrhgfgggtgfesth hqredttderjeenucfhrhhomhepfdftohhnucfprghtrghlihgvfdcuoehrohhnsehrohhn nhgrthgrlhhivgdrtghomheqnecuggftrfgrthhtvghrnhepffduteevteffueethfelle dvtdefhfekhfdvgfehudejveeijeekvddvtdejveegnecuvehluhhsthgvrhfuihiivgep tdenucfrrghrrghmpehmrghilhhfrhhomheprhhonhesrhhonhhnrghtrghlihgvrdgtoh hm X-ME-Proxy: Feedback-ID: iaba146ad:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA for ; Fri, 15 Jul 2022 07:55:38 -0400 (EDT) From: "Ron Natalie" To: "The Eunuchs Hysterical Society" Date: Fri, 15 Jul 2022 11:55:38 +0000 Message-Id: In-Reply-To: References: User-Agent: eM_Client/9.0.1755.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable Message-ID-Hash: QXBBCABZ536KQBIOKPX7NZARPOMFVPBI X-Message-ID-Hash: QXBBCABZ536KQBIOKPX7NZARPOMFVPBI X-MailFrom: ron@ronnatalie.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 X-Mailman-Version: 3.3.6b1 Precedence: list Reply-To: Ron Natalie Subject: [TUHS] ECU List-Id: The Unix Heritage Society mailing list Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: I had an ECU connecting the BRL-GATEWAY to the Imp in another building. =20 Rutgers also used an ECU to get their internet connection of the=20 Columbia IMP. When visiting BBN=E2=80=99s NOC I noted little red squares= on=20 the network map for my site. I was told these signified an ECU and it=20 is because it causes problems when the host crashes. Let me explain this quaint piece of operation. Both the IMP and the LH or DH host interface have a relay that indicates=20 the interface is powered up. The idea is that if you shutdown the=20 machine (or the imp) the relay fails open. That=E2=80=99s fine for a gro= ss=20 shutdown, but let=E2=80=99s say the machine just hangs. The IMP has a feature called =E2=80=9CTARDY DOWN.=E2=80=9D If you stop acc= epting=20 packets for a while, the thing declares you =E2=80=9CTARDY DOWN=E2=80=9D (e= ffectively=20 down for the rest of the net). This is signified on the later C-30=20 imps by the display register bit for that host flashing. Now the IMP=20 says, =E2=80=9CHey, let me try to wake this guy up.=E2=80=9D It does this = by dropping=20 its relay for a second hoping to trick the host into thinking it has=20 rebooted and it should reinitialize. Of course, this gambit rarely=20 works, but if the host did wake up, if it starts processing messages=20 again, the IMP says =E2=80=9CAll is well=E2=80=9D and declares the host up. Now, what if you had an ECU. Well, when the IMP flaps it=E2=80=99s relay, = the=20 ECU says =E2=80=9CHey, something happened to the IMP.=E2=80=9D I better r= eset=20 everything including any buffered packets. The ECU actually buffers=20 three packets or so while it is transferring them to the other end. =20 Well, now that the buffer is empty, it can take three more packets. =20 The IMP declares it up. Of course, the host isn=E2=80=99t really there, s= o the=20 packets just stay there and then the ECU fills up and stops answering=20 the IMP and the IMP eventually declares it TARDY DOWN again. Lather, Rinse, Repeat. This wouldn=E2=80=99t be so bad except that every time there=E2=80=99s a tr= ansition a=20 message is printed out in the NOC. So a dead host on an ECU causes a=20 couple of messages to be printed every three minutes until someone does=20 something about it. Later, we had similar fun and games with the EGP protocol. The=20 protocol suggest you not declare the peer up until after you receive n=20 (where n =3D 3) hello messages. I=E2=80=99m more optimistic than that. = My=20 implementation sent a =E2=80=9COK, You=E2=80=99re up=E2=80=9D response afte= r a single HELLO. =20 Of course, this pissed off some other client who said, I can=E2=80=99t be u= p=20 after only one HELLO, I better start the whole thing over again. Lather, Rinse, Repeat.