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

Miroslav Lichvar <mlichvar@redhat.com> Wed, 04 September 2019 09:51 UTC

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Date: Wed, 4 Sep 2019 11:51:11 +0200
From: Miroslav Lichvar <mlichvar@redhat.com>
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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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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