Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

RE: FW: 664b/66b frame alignment in SONET payload


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).


- Tom

-----Original Message-----
From: Wesley Lee [mailto:wlee@xxxxxxxxxx]
Sent: Friday, June 16, 2000 11:48 AM
To: Thomas Dineen
Cc: 'rabynum@xxxxxxxxxxxxxx'; 'erikt@xxxxxxxxxxxxxxxxxx';
Subject: Re: FW: 664b/66b frame alignment in SONET payload


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
is that an aligner function will be needed to handle this "wrapping". Not a
deal, only that it may entail a 66 to 1 mux which some might want to avoid
high speed.

-Wesley Lee

Thomas Dineen wrote:
> > Gentlepeople:
> >
> >       Maybe I am missing something here but I think this is a
> >
> >       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
> > SPE to another! The N+1 th SPE follows the Nth SPE in the same manor
> > 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)

Lucent Microelectronics Enterprise LAN Division - West
1381 McCarthy Blvd, Miltpitas, CA 95035
Work: 408-952-8822  FAX : 408-952-8887   wlee@xxxxxxxxxx