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Re: 664b/66b frame alignment in SONET payload


This sounds like a reasonable approach insofar as WIS frame delineation goes.
However, the 64B/66B PCS sits "above" the WIS and may not know or care that it
is in WAN mode. Therefore, 66B codes at the receiver may be aligned on odd-bit
as well as even-bit boundaries and the reduction in valid sync locations from 66
to 33 seems negligible.

Best Regards,

Erik Trounce wrote:
> Hi,
> I have a question regarding alignment of the PCS 66-bit frames
> within the SONET payload (in WAN mode obviously).  My understanding
> is that the PCS 66-bit frames can and will cross SONET frames, and
> obviously they will not begin on octet boundaries.  However, will
> it be specified that the PCS frames will sit on even-bit boundaries,
> reducing the valid sync locations from 66 to 33?
> Erik
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