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

Heiko Gerstung <heiko.gerstung@meinberg.de> Tue, 03 September 2019 08:31 UTC

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Date: Tue, 3 Sep 2019 10:31:42 +0200
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Thread-Topic: [Ntp] Antw: Re: Calls for Adoption -- NTP Extension Field drafts -- Four separate drafts
References: <heiko.gerstung@meinberg.de> <F9ECE897-2A6D-4336-86B6-88F87FC4BA89@meinberg.de> <20190903081335.15AB8406062@ip-64-139-1-69.sjc.megapath.net>
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From: Heiko Gerstung <heiko.gerstung@meinberg.de>
To: Hal Murray <hmurray@megapathdsl.net>
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Subject: Re: [Ntp] Antw: Re: Calls for Adoption -- NTP Extension Field drafts -- Four separate drafts
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Hal, 

I believe you quoted Harlan (although I agreed to him), most probably this is caused by Outlook for Mac's incredibly bad quoting behavior... Apologies for this ...

I would think that we either carefully craft the v5 packet format in a way that the information required to create a v3/v4 response is still in the same place or, if that is not possible, face the fact that a v4 server cannot respond to a v5 request. This is, IMHO, acceptable. In this case we might change the packet format for v5 so dramatically that the most common v4 implementations will end up ignoring this request. 

But I believe it should be possible to make sure that the v5 packet format allows a v4 server to respond with a v4 packet. The location in the packet for things like the timestamps could be preserved, I guess. What else is copied from the request in v4 implementaions?

Regards,
  Heiko

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On 03.09.19, 10:21 "Hal Murray" <hmurray@megapathdsl.net> wrote:

    
    heiko.gerstung@meinberg.de said:
    >     I'm saying that if a v3 system gets a v4 (or greater) packet, the v3
    >     system should respond with a v3 packet. 
    
    It can't.  There are fields in a NTP v3 reply that are copied from the request 
    packet.  The v3 only system doesn't know how to find them in a v4 packet.
    
    (For v3 and v4, they may be in the same place, but that may not be true for 
    v5.)
    
    
    -- 
    These are my opinions.  I hate spam.