[58456] in North American Network Operators' Group
Re: NTp sources that work in a datacenter (was Re: Is latency equivalent
daemon@ATHENA.MIT.EDU (N. Richard Solis)
Wed May 14 13:39:07 2003
Date: Wed, 14 May 2003 13:38:32 -0400
From: "N. Richard Solis" <nrsolis@aol.net>
To: "Steven M. Bellovin" <smb@research.att.com>
Cc: "Joel Jaeggli" <joelja@darkwing.uoregon.edu>,
"Steve Francis" <steve@expertcity.com>, Michael.Dillon@radianz.com,
nanog@merit.edu
In-Reply-To: <20030514163843.7EA697B6C@berkshire.research.att.com>
Errors-To: owner-nanog-outgoing@merit.edu
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.<br>
<br>
-Richard<br>
<br>
<br>
<span type="cite">Steven M. Bellovin wrote:</span>
<p> </p>
<blockquote type="cite"
style="border-left: thin solid blue; padding-left: 10px; margin-left: 0pt;"> <tt> <br>
In message
<a class="moz-txt-link-rfc2396E" href="mailto:Pine.LNX.4.44.0305140802170.7544-100000@twin.uoregon.edu"><Pine.LNX.4.44.0305140802170.7544-100000@twin.uoregon.edu></a>, Joel
Jae <br>
ggli writes: <br>
> <br>
> <br>
>Also if you just need a high level of syncronization between the
time on <br>
>all your hosts you can just deploy one standalone ntp server, sync
it <br>
>against public time sources and get everything synced against that.
its <br>
>probably a 95% solution to most people's timeing needs. <br>
> <br>
<br>
If I recall correctly, NTP assumes that latency = RTT/2. You might <br>
make it work well for his application *if* you set up your tree so that<br>
your paths are each one hop, or at least symmetric over your network. <br>
<br>
--Steve Bellovin, <a
href="http://www.research.att.com/%7Esmb">http://www.research.att.com/~smb</a>
(me) <br>
<a href="http://www.wilyhacker.com">http://www.wilyhacker.com</a>
(2nd edition of "Firewalls" book) <br>
<br>
<br>
<br>
</tt> </blockquote>
