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