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


Not allowing 66-bit frames to span two WIS frames does not matter since Ethernet
packets will likely span two WIS frames anyway. The WIS must buffer enough
information on Rx and Tx sides to account for at least WIS overhead and clock
tolerances. The buffering requirements for a 66-bit frame spanning two WIS
frames are negligible relative to the those to support WIS OH. 

Best Regards,

Wesley Lee wrote:
> Hi,
> Related to Erik's question, it gets kinda messy to extract
> the 66-bit code words which wrap around the ends of the SONET
> payload (a lot of muxing would be necessary since the wrap point
> would be at arbitrary bit boundaries).  Just thinking out loud,
> would it be possible to increase the Path overhead by 8 bits, or
> subtract it by 58 bits so that the 66-bit code words fit within
> the SPE without wrapping.
> Regards,
> -Wesley Lee
> --------------------------------------------------------------------
> 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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