Re: [Ntp] Antw: Re: Calls for Adoption -- NTP Extension Field drafts -- Four separate drafts

Harlan Stenn <stenn@nwtime.org> Mon, 02 September 2019 12:52 UTC

Return-Path: <stenn@nwtime.org>
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 ACAF0120119 for <ntp@ietfa.amsl.com>; Mon, 2 Sep 2019 05:52:37 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.901
X-Spam-Level:
X-Spam-Status: No, score=-1.901 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_NONE=-0.0001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
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 Zj2ZTyJ55hDN for <ntp@ietfa.amsl.com>; Mon, 2 Sep 2019 05:52:36 -0700 (PDT)
Received: from chessie.everett.org (chessie.everett.org [66.220.13.234]) (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 005A4120110 for <ntp@ietf.org>; Mon, 2 Sep 2019 05:52:35 -0700 (PDT)
Received: from [10.208.75.157] (75-139-194-196.dhcp.knwc.wa.charter.com [75.139.194.196]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by chessie.everett.org (Postfix) with ESMTPSA id 46MVPP0ShLzL7Y; Mon, 2 Sep 2019 12:53:13 +0000 (UTC)
To: ntp@ietf.org
References: <5D66392D020000A100033273@gwsmtp.uni-regensburg.de> <8F6BAF5F-CC7B-47B9-90FD-BD20D6ABE845@meinberg.de> <20190828103752.GI24761@localhost> <3f4b55ca-02d9-a470-229b-40860866efbf@nwtime.org> <20190828111458.GJ24761@localhost> <e50112dd-f918-1135-74c8-a738ecb70b70@nwtime.org> <55867E75-9813-466B-8E57-0E157DE5AEB9@meinberg.de> <d308b5d4-3d6e-981b-3dfc-9d5938bad78d@rubidium.se> <252618a3-d2fb-d5b1-baa4-72b16ef0f845@nwtime.org> <e5b16adb-eddb-fadd-4940-9d97685a36e4@rubidium.se> <20190902124303.GF15024@localhost>
From: Harlan Stenn <stenn@nwtime.org>
Openpgp: preference=signencrypt
Autocrypt: addr=stenn@nwtime.org; prefer-encrypt=mutual; keydata= mQGNBFI2xmQBDACrPayw18eU4pIwCvKh7k0iMkAV9cvzs49kBppM+xoH+KKj4QWmkKELD39H ngQnT3RkKsTLlwxyLqPdUmeQNAY2M5fsOK+OF6EvwLPK9hbmE3Wx2moX+sbEUxJ2VzFhKSKb OPZALXwk1XxL0qBedz0xHYcDwaSAZZkEFXURv2pDIdrmnoUnq2gdC8GpoFJiXoUaCLSYzzaY ac4Njw7Mue8IqfzRQb70aMjXl/qmsmfmEVAyGXywDdc/ler4XSgiuYOV7Kf69bj9PFZZSMdJ MWgEyZH6lJ0TU5ccR2zp5ZRmWzQQkxJMyH2th7q0Nmz3aX4A0K4yE0Ba9/5Dr7ctpF15BrMF aEo4s5lwI6tUnkgMWo265mMzCz4mAPV/ac0w0OXQg7r9E2r0+dRapnzUlG43D0JLDqDr9uRR L6IrRQqoCWUC75lfmPYQYSlaTJaK68r3lXd0z1cXJUgVtEL5H3/Z71R2B20twcQVAnw2iIH6 L5vdrsIjHrMmkqRVbs9nNyEAEQEAAbQ5SGFybGFuIFN0ZW5uIChOZXR3b3JrIFRpbWUgRm91 bmRhdGlvbikgPHN0ZW5uQG53dGltZS5vcmc+iQG5BBMBAgAjBQJSNsblAhsvBwsJCAcDAgEG FQgCCQoLBBYCAwECHgECF4AACgkQyIwAt1pH+kBlzgv/QOg70vdj8wU/z97UPdlbxtN4THAB gfSX4N0VPKT5fjX1tFhuXZQAOv7wedR3Trh7TGteyg33TBAFf9A42mXZKi1IxAiQG118Hd8I 51rXwnugURIYQaIyQI+vbchRbwVyz+mVLTI/h6FdbsVzT4UFmir+ZMkb/XeZPu0HItk4OZHE 6hk+TuTiCnlqlCPLq371fXV54VOb91WZYD8EQFtK02QHGHsQqWvapdphiDVpYehmsPyiTESq NMKLVtjtyPkQ6S7QF3slSg+2q3j8lyxEA78Yl0MSFNU8B/BtKgzWP2itBOfi+rtUKg+jOY1V /s2uVk2kq2QmHJ/s5k5ldy3qVvoTpxvwBe0+EoBocTHYt+xxp0mTM6YY1xLiQpLznzluqg9z qtejX1gZOF4mgLiBIrhXzed3zsAazhTp5rNb1kn0brZFh6JC5Wk941eilnA4LqX8AWo0lmwo eb+mpwZK/5lNdage/anpVqft9wJ/8EcvST9TLUO4fPrmT3d/0LpWuQGNBFI2xmQBDADXLsBk I7CSa5UXlrNVFJQHER1VxRBKqjWWCh/8Qv9v3p3NrIc2UnhoZ1uWQ2voBGty5Xfy9k4afV5k WwDyRDUIb7PX+Tj4HjVVr7qvnOVe/0KzZpNq0Azd0ggFbsM+8mydktHIwJykW0NUsGwPRYuD OA0Lro0ohb5IiCt3sSQi1X1hYjo7O1Vmn8Gy/XYOnhnMux+5zDPO2yTkCNX5PocYi9IJJy6p Mq1yQV4Y2Dl8KtQzvtq55vCUxx6n0MMzFViGwNW6F4ge9ItO4tDScsgowDrHa208ehwOpv/i wjf93lCClQ6vaKmOBX872K/tdY/hwhxPPjgl1bcrOwMRYVemOPPehwnXH5bwclk1hvDQdkJQ 5pJOkE4VCryTF/iDAt4g2QnHocUwt3b6/ChUUWmj2GZ22OR12rbnCtLedwp0DpViKPUCQHBO vpgXdzE/L9zWar9fqM0EREMgfWbsJc9028qluCcFLIN1gYsq4cC+YGAcOu7HOI5orBBV4m9j XfsAEQEAAYkDPgQYAQIACQUCUjbGZAIbLgGpCRDIjAC3Wkf6QMDdIAQZAQIABgUCUjbGZAAK CRDfCQ/G52/8P/uWDACe7OEM+VETDRqjQgAwzX+RjCVPvtgrqc1SExS0fV7i1mUUxr/B8io3 Y1cRHFoFKmedxf8prHZq316Md5u4egjFdTT6ZqEqkK0hvv+i0pRpCa5EX9VIStcJStomZp8F cY34grA+EOWITaLQ4qNZUP7rf2e7gq1ubQTj7uLr6HZZvMZ5em+IvrOWEuWDI6yOiI6px04w RDfkoR2h6kgdw4V0PT4NjK9WYYKrVCf1bjLlVImNBEcXfvlUTrIYO8y6ptvoUsBQky5pQRvP 99Pn42WfyLy50aII6+vyudD4T0yLjXAz4KteUttxtIte64m/F9/7GEIZAxTUcLyOq/7bP4le h39jBckwc62iYzeK/VkU/bMMh2D68Z3QylMnhhcW27BcgQHPKsHhmFa2SNytYcuQiSdf9+pj 4i32ETz1nJAvYAAqgTF/0PL+8ZNQoEpe/n9woMKrlZrqD4EgFmhQ3bNVhlaXz1nuTZDrwPt1 yMxBuUNbCF4jFnaruwrSiGTRoIfUZQwAjQglahrV4/mcjfnvbNoseHX0PKd9q+wjg7MIjWqr f2CI8Fa6MdanqwYphz43I2yXANKFZuMWsWqyQYlvGuPUlUUcAL3stp24RkzDB1Q+JS0IZJST T2JSu0aTfUdWVNqr2UI19eX+zxbOTckSi3Ng14ezG8ZX194ZH10b8JzntQOwmA20pd5JDhug zQfASER+CZDiPPcQ4mvC4y7rMrfV6XGQbDynC3ekDxo8SC5SvjaczXMwXg6SZ8iFtEWmEwW9 r7zPjjIPDrX8w5LXBgxArM5o/HbERpc2EdAvMh1D7LC0SvmoE7fBKxsicVBe4h6vXjEZ+LLr /wuZiBld9OnxAUIpwptbBspO6WKTQYvgFH2OeDG27hiE5P4Xs4WSp5j9ez8OVB1iZnA2nCQ+ tNTjO8c+C/P92vPLx5+bpGRXTXMNaLh34PS3ZsYoUDkKZNhczRZUWJ7nynSbeeyF+QW7SLwA qY7O7dyk9LFTsfJqRQJ7tWnIAjJPCwmSgQ8Kl0UJ
Message-ID: <24c6b80b-2bbb-e555-9eaf-34f964947d6e@nwtime.org>
Date: Mon, 2 Sep 2019 05:52:33 -0700
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0
MIME-Version: 1.0
In-Reply-To: <20190902124303.GF15024@localhost>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Archived-At: <https://mailarchive.ietf.org/arch/msg/ntp/tfLvXZGn78WrEIG7gvtNWoVpuOg>
Subject: Re: [Ntp] Antw: Re: Calls for Adoption -- NTP Extension Field drafts -- Four separate drafts
X-BeenThere: ntp@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: <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, 02 Sep 2019 12:52:38 -0000


On 9/2/2019 5:43 AM, Miroslav Lichvar wrote:
> On Mon, Sep 02, 2019 at 01:32:11PM +0200, Magnus Danielson wrote:
>>>> If I only had time to describe all the things I would do to enhance NTP,
>>>> it has a number of built-in assumptions which is not useful or correct.
>>> How about a list of at least some of the built-in assumptions that you
>>> think are not useful or correct?
>>
>> From the top of my head a few:
>>
>> The Allan interception point is based on incorrect theory of the noise.
>>
>> Rather than drive things to highest stratum, going to closes
>> intermediate node and then let that do aggregated questioning to
>> increase the width of single stream rather than separate allows better
>> noise surpression of asymmetric delays.
>>
>> The frequency/phase lock-in methods is dated and has failures in
>> error-handling, especially with how calibration works and can become
>> incorrect. There is simpler methods with much better error-handling.
> 
> If I understand it correctly, those are not a problem of the NTPv4
> format or protocol, but rather RFC 5905. I'm not sure if a new NTP
> version is needed to fix that. A draft could specify that NTPv4
> implementations are free to use different algorithms and models of the
> clock than what is specified in RFC 5905. That would just describe the
> current state. I think it was an idea for the NTPv5 specifications
> that it would have no algorithms, only the message format and
> protocol.

This was discussed for NTPv4 as well.

The thing is that NTP is a complete specification with a goal of time
synchronization that includes *known behavior in the face of impulse
response*.

If one uses different algorithms with different impulse response
behaviors, this can trigger oscillations and even unstable tracking (the
wheels fly off the bus).

Be careful what you wish for.

> What I wanted to collect were issues that may require changes in the
> format itself. Like insufficient resolution of the root delay and
> dispersion, missing timescale identification, minimum length of
> extension fields, etc.
> 

-- 
Harlan Stenn, Network Time Foundation
http://nwtime.org - be a Member!