Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

RE: [RPRWG] 802.17 Outline: Stratum Clock distribution?

It seems nobody really knows what it really means or why this section suddenly appeared in the outline for .17.
If it's like James says, synchronization for circuit emulation this is indeed not something that should be part of the RPR standard.
Also since we are not defining a PHY layer, I don't understand why we should bother with synchronization or lack of synchronization in the different PHY layers we are going to use.

Can we momentarily remove this section from the outline. If in the future we all agree on content and purpose of this section, we can always add it again.


"Chan, James" <jchan@xxxxxxxxxxxxxxxxx> on 21/11/2001 22:32:51
 To:      "'djz@xxxxxxxxxxx'" <djz@xxxxxxxxxxx>, Jeanne DE    
 cc:      stds-802-17@xxxxxxxx                                
 Subject: RE: [RPRWG] 802.17 Outline: Stratum Clock           

Stratum Clock Distribution to me means ANSI T1.101 Synchronization hierarchy
standard. This is very different to time-of-day clocks. Synchronization is
necessary from PSTN (TDM voice) perspective. It may also be required for a
RPR network supporting circuit emulation services (there may be other ways
to do it without synchronization). However, this is an implementation
specific issue which should not be part of the RPR standard. Individual
vendors may choose to do it as their differentiator.

I was not aware of stratum clock discussion in the last meeting. Can any
else shed some light?


James Chan

-----Original Message-----
From: David James [mailto:djz@xxxxxxxxxxx]
Sent: Wednesday, November 21, 2001 10:14 AM
To: Jeanne.De_Jaegher@xxxxxxxxxx
Cc: stds-802-17@xxxxxxxx
Subject: RE: [RPRWG] 802.17 Outline: Stratum Clock distribution?


Some physical layers have no provisions for accurately
synchronizing time-of-day clocks (GMT like clocks) of
clock slave's to clock masters.

For physical layers without such services, this clause
describes how such time-of-day clocks can be accurately
synchronized by MAC-level services.

From IEEE Std 1394 Serial Bus experiences, as well as
the telecom industry as a whole, the value of synchronous
transfers is greatly increased if time-of-day clocks
can also be synchronized.


David V. James, PhD
Chief Architect
Network Processing Solutions
Data Communications Division
Cypress Semiconductor
110 Nortech Parkway
San Jose, CA 95134
Work: +1.408.942.2010
Cell: +1.650.954.6906
Fax:  +1.408.942.2099
Work: djz@xxxxxxxxxxx
Base: dvj@xxxxxxxxxxxx

> -----Original Message-----
> From: owner-stds-802-17@xxxxxxxxxxxxxxxxxx
> [mailto:owner-stds-802-17@xxxxxxxxxxxxxxxxxx]On Behalf Of
> Jeanne.De_Jaegher@xxxxxxxxxx
> Sent: Wednesday, November 21, 2001 3:17 AM
> To: stds-802-17@xxxxxxxx
> Subject: [RPRWG] 802.17 Outline: Stratum Clock distribution?
> Good morning,
> Can someone tell me what the section over Stratum Clock
> Distribution covers?
> Thank's
> Jeanne