From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: tuhs-bounces@minnie.tuhs.org X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE autolearn=ham autolearn_force=no version=3.4.1 Received: from minnie.tuhs.org (minnie.tuhs.org [45.79.103.53]) by inbox.vuxu.org (OpenSMTPD) with ESMTP id 71ce6777 for ; Sun, 17 Jun 2018 15:59:21 +0000 (UTC) Received: by minnie.tuhs.org (Postfix, from userid 112) id 22DF3A1564; Mon, 18 Jun 2018 01:59:20 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id 798B59EDEE; Mon, 18 Jun 2018 01:58:56 +1000 (AEST) Received: by minnie.tuhs.org (Postfix, from userid 112) id C646B9EDE4; Mon, 18 Jun 2018 01:58:53 +1000 (AEST) Received: from accordion.employees.org (accordion.employees.org [198.137.202.74]) by minnie.tuhs.org (Postfix) with ESMTPS id 1632E9BC34 for ; Mon, 18 Jun 2018 01:58:53 +1000 (AEST) Received: by accordion.employees.org (Postfix, from userid 1736) id D2B0B2D5259; Sun, 17 Jun 2018 15:58:52 +0000 (UTC) Date: Sun, 17 Jun 2018 16:58:52 +0100 From: Derek Fawcus To: Noel Chiappa Message-ID: <20180617155852.GA12237@accordion.employees.org> References: <20180617143610.B53FE18C0A7@mercury.lcs.mit.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180617143610.B53FE18C0A7@mercury.lcs.mit.edu> User-Agent: Mutt/1.9.4 (2018-02-28) Subject: Re: [TUHS] core X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: tuhs@tuhs.org Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" On Sun, Jun 17, 2018 at 10:36:10AM -0400, Noel Chiappa wrote: > > From: Derek Fawcus > > > Are you able to point to any document which still describes that > > variable length scheme? I see that IEN 28 defines a variable length > > scheme (using version 2) > > That's the one; Version 2 of IP, but it was for Version 3 of TCP (described > here: IEN-21, Cerf, "TCP 3 Specification", Jan-78 ). Ah - thanks. So my scan of it suggests that only the host part of the address which were extensible, but then I guess the CIDR scheme could have eventually been applied to that portion. The other thing obviously missing in the IEN 28 version is the TTL (which appeared by IEN 41). > > and that IEN 41 defines a different variable length scheme, but is > > proposing to use version 4. > > Right, that's a draft only (no code ever written for it), from just before the > meeting that substituted 32-bit addresses. > > > (IEN 44 looks a lot like the current IPv4). > > Because it _is_ the current IPv4 (well, modulo the class A/B/C addressing > stuff). :-) I wrote 'a lot', because it has the DF flag in the TOS field, and an OP bit in the flags field; the CIDR vs A/B/C stuff didn't really change the rest. But yeah - essentially what we still use now. Now 40 years and still going. The other bit I find amusing are the various movements of the port numbers, obviously they were originally part of the combined header (e.g. IEN 26), then the IEN 21 TCP has them in the middle of its header, by IEN 44 it is sort of its own header split from the TCP header which now omits ports. Eventually they end up in the current location, as part of the start of the TCP header (and UDP, etc), essentially combining that 'Port Header' with whatever transport follows. DF