Re: code-word alignment location
Ben, Una,
I believe that Una answered her own question by qualifying/prefixing "codeword
alignment" with "PCS".
In the case of the UniPHY proposed by Mr. Howard Frazier, the PCS consists of
the following elements:
1) 64B/66B CODEC
2) SONET framer
3) x^7 + x^6 +1 scrambler
Byte alignment is relevant on the 64B side of the 64B/66B CODEC as well as all
non-66B payload of the SONET frame.
Synchronization is performed at the 66b level to the 1/0 or 0/1 sync bits as Mr.
Ben Brown indicates. This process is exactly the same whether or not the WIS is
bypassed in the UniPHY.
Best Regards,
Rich
--
"Brown, Ben [BAY:NHBED:DS48]" wrote:
>
> Una,
>
> I thought I'd throw in a response to your aside using a new thread.
>
> > Una Quinlan wrote:
> >
> > [ Aside: Does PCS codeword alignment belong in the PMA/WIS or the PCS?].
> >
>
> In 1000Base-X, code-word alignment (to the comma) occurred in the PMA.
> With a break down (from the Uni-PHY proposal) of PMD - PMA - WIS - PCS,
> the PMA cannot provide alignment. The WIS needs to align on A1/A2. From
> this, the WIS provides byte aligned data to the PCS. If the PCS
> is 64b/66b, this byte alignment is useless and 66b alignment is done
> to the 1/0 or 0/1 sync bits. The PMA can't participate in any of this
> because the WIS is optional and both the WIS and PCS require different
> alignment mechanisms. Implementations can do anything they want but the
> standard needs to keep these separate.
>
> Ben
>
> --
> -----------------------------------------
> Benjamin Brown
> Router Products Division
> Nortel Networks
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> -----------------------------------------
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