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RE: [PWE3] comments on draft-ietf-pwe3-requirements-03.txt
Yaakov and all,
Following your logic, VC4 does not belong to SDH because "S" in SDH
stands for SYNchronous, while VC4 clocks within an STM-n stream
are controlled separately via - each via its own pointer adjustments.
IMHO, Neil's remark correctly reflects the common understanding
of the Telecom world to which the notion belongs.
With best regards,
Sasha Vainshtein
email: sasha@axerra.com <mailto:sasha@axerra.com>
tel: +972-3-7659993 (office)
+972-8-9254948 (res.)
+972-58-674833 (cell.)
> -----Original Message-----
> From: Yaakov Stein [mailto:yaakov_s@rad.co.il]
> Sent: Tuesday, October 08, 2002 10:17 AM
> To: neil.2.harrison@bt.com; stbryant@cisco.com
> Cc: pwe3@ietf.org
> Subject: RE: [PWE3] comments on draft-ietf-pwe3-requirements-03.txt
>
>
>
> > E1 and T1 belong to PDH and only PDH.
>
> Sorry Neil, but PLESIOchronous refers ONLY
> to multiplexing of sources with NEARLY (BUT NOT EXACTLY)
> the same clock (PLESIO is Greek for near or close).
> (See G.701)
>
> PDH thus refers to the hierarchy of multiplexing schemes
> that use with stuffing bits, e.g. E2,T2,E3,T3.
>
> E1 and T1 mandate a single clock for all the DS0s they multiplex.
> They are thus not PLESIOchronous by any stretch of the imagination.
> They are simply synchronous (SYN means SAME).
>
> Please do not fall into the same pit as someone did in
> a previous thread on this list, and claim that various ITU
> standards refer to E1 and T1 as PDH. They don't.
> They use the term BASED ON the 1544 kbps or 2048 kbps hierarchy.
> The PDH hierarchy is BASED ON the E1 or T1 clocks,
> but the E1/T1 signals themselves are NOT PDH.
>
> Y(J)S
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