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Re: wis scrambler vs 64/66 scrambler


The x7+x6+1 scrambler is the SONET scrambler within the WIS.
The x58+x19+1 (or 1+x39+x58 as it is now defined) scrambler,
is within the PCS (64B/66B). They are not the same thing and,
when the WIS is enabled, they are both used.


Eric Ng wrote:
> Hi,
> In the blue book the wis scrambler is x7+x6+1, only the
> 6th and 7th term are xor and feedback to the beginning
> of the 7-bit shift register.
> However, in the 64/66PCS section x58+x19+1 is used but
> this time the scrambled output xor 58th xor 19th and
> feed back to the beginning of the 58-bit shift registers.
> The two equations are very similar but the drawing in the
> bluebook suggested otherwise.  Also, base on the drawing,
> the wis scrambler/descrambler would be the same while the
> 64/66 scrambler and descrambler are different. I must have
> misunderstood some fundamental.  I hope someone could clarify
> this for me.
> Thanks in advance.
> regards,
> --
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