Re: [Ntp] Antw: [EXT] Re: Robert Wilton's Discuss on draft‑ietf‑ntp‑interleaved‑modes‑05: (with DISCUSS and COMMENT)

Miroslav Lichvar <mlichvar@redhat.com> Mon, 26 July 2021 09:15 UTC

Return-Path: <mlichvar@redhat.com>
X-Original-To: ntp@ietfa.amsl.com
Delivered-To: ntp@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id B720B3A2232 for <ntp@ietfa.amsl.com>; Mon, 26 Jul 2021 02:15:14 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.549
X-Spam-Level:
X-Spam-Status: No, score=-2.549 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.452, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1024-bit key) header.d=redhat.com
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id x7Yy9SJNpaWB for <ntp@ietfa.amsl.com>; Mon, 26 Jul 2021 02:15:10 -0700 (PDT)
Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 7FEBE3A2231 for <ntp@ietf.org>; Mon, 26 Jul 2021 02:15:10 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1627290909; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=P9pV6adJB9gVITHfeB7uCXN9wj4eRjIEqLf/Yj6LnBQ=; b=Pe3Q9qhKZQHN4pILXZuvRWkMEYLn8cikZK9jvldj1jGYT8qkt5JHgR8+mhBTWhnxWn1LsS 1dW9mgqZ1Y9Nu975FQ0pcZNVn9ozvsUSKUg5JUVeGoK2dsPg2EfIT+d1YSyPxRq6f+pG/B SMrugdVJsyIeFXsAcaOXE/U9C9ZayVg=
Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-280-Um9D5ymRPH22Tc3xMRt_VQ-1; Mon, 26 Jul 2021 05:15:06 -0400
X-MC-Unique: Um9D5ymRPH22Tc3xMRt_VQ-1
Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id ED948107AD81; Mon, 26 Jul 2021 09:15:05 +0000 (UTC)
Received: from localhost (holly.tpb.lab.eng.brq.redhat.com [10.43.134.11]) by smtp.corp.redhat.com (Postfix) with ESMTPS id F417219D9B; Mon, 26 Jul 2021 09:15:04 +0000 (UTC)
Date: Mon, 26 Jul 2021 11:15:03 +0200
From: Miroslav Lichvar <mlichvar@redhat.com>
To: Erik Kline <ek.ietf@gmail.com>
Cc: Ulrich Windl <Ulrich.Windl@rz.uni-regensburg.de>, "ntp@ietf.org" <ntp@ietf.org>
Message-ID: <YP59F4YqwsevWjhz@localhost>
References: <YNrbjCDF4/609dg/@localhost> <D999D237-5A25-4E84-99D0-EE5DB2B13411@cisco.com> <YN3ZzPN5LOsAjmz6@localhost> <DM4PR11MB5438D8450E7B90D363929640B5119@DM4PR11MB5438.namprd11.prod.outlook.com> <YPaunrczI/inrtMP@localhost> <60F6B70A020000A100042803@gwsmtp.uni-regensburg.de> <YPa9H7IV2wITWKrD@localhost> <CAMGpriWzV4--_Nw9hsNC01U7f1FzjZQ8sNdJz+25dxhFtuDUvg@mail.gmail.com> <YPkxqtpgzD7g8Anz@localhost> <CAMGpriU3PKheo1uWStRid4z8mMuUvLwwkSx0j8+js=vOgnV3WQ@mail.gmail.com>
MIME-Version: 1.0
In-Reply-To: <CAMGpriU3PKheo1uWStRid4z8mMuUvLwwkSx0j8+js=vOgnV3WQ@mail.gmail.com>
X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23
Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mlichvar@redhat.com
X-Mimecast-Spam-Score: 0
X-Mimecast-Originator: redhat.com
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Archived-At: <https://mailarchive.ietf.org/arch/msg/ntp/YzdMCZ6iabu89Ca7w8n6eIZidiw>
Subject: Re: [Ntp] =?utf-8?q?Antw=3A_=5BEXT=5D_Re=3A_Robert_Wilton=27s_Discus?= =?utf-8?b?cyBvbiBkcmFmdOKAkWlldGbigJFudHDigJFpbnRlcmxlYXZlZOKAkW1vZGVz?= =?utf-8?b?4oCRMDU6ICh3aXRoIERJU0NVU1MgYW5kIENPTU1FTlQp?=
X-BeenThere: ntp@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Network Time Protocol <ntp.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/ntp>, <mailto:ntp-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/ntp/>
List-Post: <mailto:ntp@ietf.org>
List-Help: <mailto:ntp-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/ntp>, <mailto:ntp-request@ietf.org?subject=subscribe>
X-List-Received-Date: Mon, 26 Jul 2021 09:15:15 -0000

On Thu, Jul 22, 2021 at 04:54:25PM -0700, Erik Kline wrote:
>     Using a 28-octet extension field to convey a single bit of information
>     is quite wasteful anyway.
> 
> While I certainly see this point, it occurred to me that if the extension
> where written to be a general "extra flags and fields" extension -- of
> which one was defined for "I speak interleaved" and rest reserved -- then
> another way to think about it is that the cost of this space would be
> amortized across the other future uses of the space.

There was a draft like that
https://datatracker.ietf.org/doc/html/draft-stenn-ntp-i-do-06

But if a significant number of existing servers doesn't respond to
requests containing unknown extension fields (RFC5905 doesn't require
that), how will the client be sure whether the interleaved mode is or
is not supported? It would need to try both and see what works.

-- 
Miroslav Lichvar