Re: FW: 664b/66b frame alignment in SONET payload
Hi Wesley,
I don't see this as a problem. Since the WIS will be removing all
SONET overhead, it will be only passing payload (payload == SPE -
POH - fixed stuff) to the PCS. The PCS should not have any
exposure to SONET framing, it will be simply receiving a datastream
at 9.58464 Mbit/s (1 payload as defined above per 125 us). The
hard(-ish) part as far as aligning is concerned will be handling the
bit alignment.
Regards,
Erik Trounce
In message "664b/66b frame alignment in SONET payload", Wesley Lee
writes:
>Hi,
>
>Just to clarify my point which I believe is a different from Erik's and
>this issue admittedly is not major. The point I was make about
"wrapping"
>refers to the wrapping the 66-bit code word within the SPE. Given that
the
>width of the SPE is 16,640 bytes (133,120 bits), the 66-bit code word
is not
>a multiple of this size, and the last code word at the end of the row
will
>be split between this row and the beginning of the next row. What this
means
>is that an aligner function will be needed to handle this "wrapping".
Not a big
>deal, only that it may entail a 66 to 1 mux which some might want to
avoid at
>high speed.
>
>-Wesley Lee
>
>Thomas Dineen wrote:
>>
>> > Gentlepeople:
>> >
>> > Maybe I am missing something here but I think this is a
non-problem.
>> >
>> > I envision a series of repeating STS-N frames with their
>> > encapsulated
>> > SPEs as one continuous repeating structure. In other words, after
>> > extracting
>> > th ubiquitous Transport and Path Overhead there is no wrap around
from one
>> > SPE to another! The N+1 th SPE follows the Nth SPE in the same
manor that
>> > the N+1 th row follows the Nth. This is especially useful when
floating
>> > SPE mode
>> > is used with payload pointers.
>> >
>> > Inherited A Sonet Problem.
>> > (Thomas Dineen)
>
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