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Re: NTp sources that work in a datacenter (was Re: Is latency equivalentto RTT?)

  • From: N. Richard Solis
  • Date: Wed May 14 13:40:36 2003

IIRC, NTP actually sends a packet with a local timestamp, sends it to a remote location for a remote timestamp, and then checks the local timestamp when the packet is received to calculate RTT.


Steven M. Bellovin wrote:

In message [email protected]"><[email protected]>, Joel Jae
ggli writes:
>Also if you just need  a high level of syncronization between the time on
>all your hosts you can just deploy one standalone ntp server, sync it
>against public time sources and get everything synced against that. its
>probably a 95% solution to most people's timeing needs.

If I recall correctly, NTP assumes that latency = RTT/2.  You might
make it work well for his application *if* you set up your tree so that
your paths are each one hop, or at least symmetric over your network.

                --Steve Bellovin, (me)
       (2nd edition of "Firewalls" book)