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Re: SONET/Ethernet clock tolerance


I am not sure why you are concerned about the regenerators budget timing
specifications.  Loop timed or derived timed systems run on the clock
specification of the incoming clock.

Thank you,
Roy Bynum

----- Original Message -----
From: Osamu ISHIDA <ishida@xxxxxxxxxxxxxxxxxxx>
To: Roy Bynum <rabynum@xxxxxxxxxxxxxx>
Cc: <stds-802-3-hssg@xxxxxxxx>
Sent: Thursday, March 30, 2000 12:04 AM
Subject: Re: SONET/Ethernet clock tolerance

> Roy,
> I have discussed about jitter budget over the end-end SONET-framed link.
> As I understand, in a chain of SONET(-lite) regenerators, the link jitter
> budget should be specified for all the chain elements.  This means each
> regenerator should meet very stringent jitter-transfer specifications.
> I think this is not the issue of +/-100ppm or +/-4.6ppm.
> It would be appreciated if you let me know about jitter-transfer spec.
> in "SONET-lite".
> Also please let me know if you have any further information about
> "SONET-lite".  I have checked the T1.416 Standard Document approved
> last December, but I can not find any statement about "+/-100ppm".
> It seems to say just "be compliant to T1.105 (=SONET)".
> My understanding at present is that there is no "SONET-lite" standard
> in ITU-T, T1, IETF, nor OIF.  Please correct me if I am wrong.
> Best Regards,
> Osamu Ishida
> At 8:37 AM -0600 00.3.29, Roy Bynum wrote:
> > The clock tolerances for regenerators (LRE) are very relaxed from those
> > line terminating equipment (LTE).  It is the LTE that does the
> > of the smaller TDM payloads into a full OC192 payload and puts the full
> > SONET overhead on it, scrambles it,  and sends it out.  The regenerator
> > a line clock recovery, unscrambles the SONET frame, uses the section
> > overhead information to determine performance and fault issues,
> > the SONET frame, and sends it out.  The regenerator re-times the signal
> > using the recovered clock, not a Stratum clock.  In the process the
> > regenerator removes any signal bit jitter that has been introduced by
> > various forms of dispersion that occur in optical fiber over any
> > Because it does not do the multiplexing and does not have the clock
> > tolerance issues that the LTE has, a regenerator is a lot less expensive
> > than an LTE.