Re: FW: 664b/66b frame alignment in SONET payload
Tom,
Thanks for bringing this up. I forgot about the "gearbox" which
puts things nice byte-size chunks :)
Regards
-Wesley Lee
Tom Alexander wrote:
>
> Hi,
>
> In the 64B/66B codec diagrams presented by Rick Walker,
> there is mention of a 66:16 "gearbox" that performs a
> width/frequency conversion. I believe this may be what
> you are referring to with respect to the aligner function.
> In this case the service interface of the 64B/66B PCS
> should be directly mappable to the service interface of
> the WIS, with no extra alignment in between (i.e., no
> alignment that is not already required for the LAN-PHY).
>
> Cheers,
>
> - Tom
>
> -----Original Message-----
> From: Wesley Lee [mailto:wlee@lucent.com]
> Sent: Friday, June 16, 2000 11:48 AM
> To: Thomas Dineen
> Cc: 'rabynum@mindspring.com'; 'erikt@nortelnetworks.com';
> stds-802-3-hssg@ieee.org
> Subject: Re: FW: 664b/66b frame alignment in SONET payload
>
> 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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> 1381 McCarthy Blvd, Miltpitas, CA 95035
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Lucent Microelectronics Enterprise LAN Division - West
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Work: 408-952-8822 FAX : 408-952-8887 wlee@lucent.com
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