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North American Network Operators Group

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Re: NTP servers

  • From: Paul Vixie
  • Date: Sat Jun 07 23:07:16 2003 ("Ejay Hire") writes:

> I was thinking about the not the closest-server problem today, and =
> realized this is a good application for BGP-DNS =
>  Making it possible to look at =
> the reqeustor's network location and retrun the "closest" servers.

you mean you believe you can predict which server is going to be best(*)
for a given client by looking at aspath length?  to quote rocky the
squirrel, "that trick never works!"

what you're looking for in terms of an ntp server is "best isochrony".
as long as the delay and loss constant it doesn't matter how high they
are.  a secondary sort term would be server load, but presumably a 
server which was too loaded could just stop answering new clients.

time, like netnews, should roughly follow router topology.  get time from
your isp and let them get it from GPS/GOES or their peers/transits/whatever.
Paul Vixie

(*) "best" could mean lowest time to last byte, lowest latency for first
byte, lowest average latency for all segments, largest tcp window size,
fewest likely retime/retransmit events; and could be file size dependent
since a satellite connection will probably win on large files whereas a
9600 baud slip line will probably win on small files... the beat goes on.

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