Re: [Ntp] New rev of the NTP port randomization I-D (Fwd: New Version Notification for draft-gont-ntp-port-randomization-01.txt)

Miroslav Lichvar <mlichvar@redhat.com> Tue, 04 June 2019 08:17 UTC

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Date: Tue, 4 Jun 2019 10:17:40 +0200
From: Miroslav Lichvar <mlichvar@redhat.com>
To: Fernando Gont <fgont@si6networks.com>
Cc: ntp@ietf.org
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Subject: Re: [Ntp] New rev of the NTP port randomization I-D (Fwd: New Version Notification for draft-gont-ntp-port-randomization-01.txt)
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On Thu, May 30, 2019 at 02:19:59PM -0400, Fernando Gont wrote:
> > If you had two clients in your network and they were synchronized to
> > the same server, there could be a significant offset between their
> > clocks if they used a fixed port. If they randomized their ports with
> > each request, the offset should be smaller and not change randomly
> > when the clients are restarted, etc.
> 
> Agreed. My question is: should one aim at the individual measurements to
> be dropped, or at the server to be un-preferred over other (possibly
> better) ones? -- I realize that in some scenarios this might happen with
> all servers, in which case the former option (have individual
> measurements dropped) might be a better option.

I think both. The client should use only the best measurements from
each server and then select the best servers for synchronization. A
server with a highly unstable delay may still be prefered over a
server with stable but larger delay, or if it better fits a cluster
of other servers.

-- 
Miroslav Lichvar