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

Heiko Gerstung <heiko.gerstung@meinberg.de> Wed, 04 September 2019 10:05 UTC

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Date: Wed, 4 Sep 2019 12:05:47 +0200
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Thread-Topic: [Ntp] Antw: Re: Antw: Re: Calls for Adoption -- NTP Extension Field drafts -- Four separate drafts
References: <mlichvar@redhat.com> <20190902095854.GC15024@localhost> <20190903120544.394CC40605C@ip-64-139-1-69.sjc.megapath.net> <20190904095111.GJ15024@localhost>
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From: Heiko Gerstung <heiko.gerstung@meinberg.de>
To: Miroslav Lichvar <mlichvar@redhat.com>, "ntp@ietf.org" <ntp@ietf.org>
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Subject: Re: [Ntp] Antw: Re: Antw: Re: Calls for Adoption -- NTP Extension Field drafts -- Four separate drafts
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Using a Ethernet mac address or an IP address will allow to identify a server if it is included in the "sync chain" data set, I therefore would definitively go for a random ID. I am not yet decided if it should be allowed to let the user assign a static ID via configuration as that would make duplicates/collisions more likely than the random ID approach. 

Regards, 
    Heiko


On 04.09.19, 11:52 "ntp im Auftrag von Miroslav Lichvar" <ntp-bounces@ietf.org im Auftrag von mlichvar@redhat.com> wrote:
> 
> On Tue, Sep 03, 2019 at 05:05:44AM -0700, Hal Murray wrote:
>> I think there are two approaches.
>> 
>> One is to use random data. The probability of a collision can
>> be made 
>> arbitrarily small by making the number of bits in the ID big
>> enough. That 
>> needs good randomness.
>> 
>> The other approach is to piggyback on some other scheme that
>> has already 
>> solved the problem.
> 
> The former makes more sense to me. We don't need the ID to be
> static.
> Generating a random number on each start should be fine.
> 
>> Can we assume that every server will have a globally routeable
>> IPv6 address? 
> 
> No. IPv6 is not universally available. Address translation is
> common, so we cannot assume an IPv4 or IPv6 address is unique.
> 
>> Can we assume that every server will have an Ethernet host address?
> 
> The vast majority will, but I'm not sure we can rely on them
> being random.
> 
>> In both cases, for multi homed servers, just pick one. After
>> that choice, 
>> it's an ID, no longer an address.
> 
> Yes. And it's important that all clients get the same ID.
> 
> -- 
> Miroslav Lichvar
> 
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