[58793] in North American Network Operators' Group
Re: Clocking Sources (was NTp sources that work in a datacenter (was
daemon@ATHENA.MIT.EDU (Peter Lothberg)
Sun Jun 1 02:23:18 2003
Date: Sat, 31 May 2003 23:22:40 PDT
From: Peter Lothberg <roll@stupi.se>
To: "N. Richard Solis" <nrsolis@aol.net>
Cc: "Spinka, Kristofer" <kspinka@style.net>, nanog@merit.edu
In-Reply-To: Your message of Fri, 16 May 2003 15:55:51 -0400
Errors-To: owner-nanog-outgoing@merit.edu
> The desire for everyone to have a timing source that is tracable to
> a Cesium clock comes from the SONET standard. If you tie two SONET
> networks together, if they both don't have timing that's tracable to
> a Stratum 1 (PRS) source, they'll drift at the points where they
> interconnect and PSE (Positive Stuff Event) and NSE (Negative Stuff
> Event) errors will be the result. This is BAD BAD BAD for the voice
> networks that are provisioned over SONET.
BITS and SONET systems do not carry time-of-day information. It's only
frequency.
Sonet/GR253C SDH/G811 stratum-1 is 1x10-11 that will give you one
pointer update every 72 days. But you can do one pointer-update every
two frames...
-P
(you do stuffing on PDH systems)
