nanog mailing list archives
Re: Clocking Sources (was NTp sources that work in a datacenter (was Re: Is latency equivalentto RTT?))
From: Peter Lothberg <roll () stupi se>
Date: Sat, 31 May 2003 23:22:40 PDT
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)
Current thread:
- Re: Clocking Sources (was NTp sources that work in a datacenter (was Re: Is latency equivalentto RTT?)) Peter Lothberg (May 31)
- <Possible follow-ups>
- Re: Clocking Sources (was NTp sources that work in a datacenter (was Re: Is latency equivalentto RTT?)) Peter Lothberg (May 31)
- pool.ntp.org NTP servers wayne (Jun 01)
- Message not available
- Re: pool.ntp.org NTP servers wayne (Jun 03)
- Re: pool.ntp.org NTP servers Curtis Maurand (Jun 05)
- pool.ntp.org NTP servers wayne (Jun 01)
- Re: Clocking Sources (was NTp sources that work in a datacenter (was Re: Is latency equivalentto RTT?)) N. Richard Solis (Jun 02)