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Re: [10GBT] Frame delineation in 10GBT


I seem to agree with the merits you pointing out
of 64/65 pcs coding and in my opinion it is worth


At 10:19 AM 8/13/2004 -0700, Hugh Barrass wrote:
>Brad et al,
>During the discussion on the proposal for framing in 10GBT, I mentioned
>that I thought the 64/65 octet encapsulation used in .3ah (Clause 61.3)
>would be a better proposition than 64b/66b (from .3ae) or 64b/65b (as
>described in the presentation). I know that this is a relatively small
>issue compared to the PAM-8 / PAM-12 discussion but I think that those
>involved in PCS definition would benefit from a good reading of the .3ah
>The main benefit of the 64/65 octet encapsulation is that it is byte
>oriented and therefore much more straightforward to fit on top of the
>byte oriented LDPC coding. It has a very low overhead (1/64, duh!) and
>does not have any alignment issue with odd size frames. It also supports
>IPG compression (although that is not relevant for 10G) and has some
>spare codepoints for adding in prequalizer feedback data if required.
>It might also be worth considering the use of 64/65 to cover the dual
>function of LDPC block delineation as well as Ethernet frame
>delineation. This would require the use of some more codepoints for
>block flags, but shouldn't be difficult to achieve. I believe that we
>could get a PCS encapsulation that is significantly simpler to define
>and implement as well as being more robust and less overhead.
>If anybody is interested in this, I'd be willing to go through it in
>more detail - or else let me know that I am wasting my breath & I'll
>drop the subject.