# Re: Maximum run length of 64/66b

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Hi Pat and Mike:

One more similar question for WIS,  i.e. after 64b/66b then go through WIS
interface,
What is the max run length?
How is the DC balancing ?

Best Regards
Happy New Year

Steven Shen
Silicon Bridge Inc.

pat_thaler@xxxxxxxxxxx wrote:

> Look at the presentation:
> http://grouper.ieee.org/groups/802/3/10G_study/public/jan00/walker_1_0100.pd
> f
> for a simulation of baseline wander with the scrambled code.
>
> Pat
>
> -----Original Message-----
> From: THALER,PAT (A-Roseville,ex1)
> Sent: Monday, December 04, 2000 3:14 PM
> To: 'Mike Jenkins'; stds-802-3-hssg@xxxxxxxx
> Subject: RE: Maximum run length of 64/66b
>
> Mike and Shen,
>
> Sorry I didn't get to answering sooner. I was busy getting
>
> The maximum run length is 66 which can occur when a data frame is
> followed by a control frame or vice versa. There is always a transition
> between the two bits of the sync header. The probability of a run of
> 65 or 66 bits is 2^64 ~ 16 * 10^18.
>
> One can AC couple just as one can with any scrambled code. On the average
> about half the bits will be zero and half will be one. The cut-off frequency
> will be much lower than for something like an 8B/10B code, but it does not
> have to go down to zero.
>
> Regards,
> Pat
>
> -----Original Message-----
> From: Mike Jenkins [mailto:jenkins@xxxxxxxx]
> Sent: Tuesday, November 14, 2000 2:45 PM
> To: stds-802-3-hssg@xxxxxxxx
> Subject: Re: Maximum run length of 64/66b
>
> Hello,
>
> Perhaps I missed it, but I haven't seen any responses to the
> question below, so let me hazard a guess and hope that someone
> corrects me if I'm wrong:
>
>  1) The max run length is 66, since the sync bits are not
>     scrambled.
>
>  2) I suspect the frequency content is sufficiently low that
>     any AC coupling would be impossible.
>
> Improved theoretical or empirical results might help 64b/66b
> serve other applications as well as this one, I would think.
> Opinions anyone?
>
> Regards,
> Mike
>
> ss_shen@xxxxxxxxxxxxxxxxx wrote:
> >
> > Hi :
> >
> > This maybe a silly question, but if someone can
> > tell me, would be much appreciated.
> >
> >  (1)  the Maximum run length of 64/66b:
> >       Before scramble, the worse run length is
> >       65 when it has 01111...... (one "0", 65 "1").
> >       What would be the maximum run length after
> >       scramble?
> >
> >   (2) DC balancing aspect of 64b/66b + scramble
> >