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Re: Hari Byte vs. Word striping

Richard Dugan,

I have seen both of your postings of 12/10, one where you agree with the
points Al Widmer has made technically, then another where you consider the
byte vs. word case a draw.  Let me point out, firstly, that the
implications of Al Widmer's points, with which you agreed, are:

       1)  Byte striping will have more complex high-speed logic than the
word striping,

       2)  Byte striping will therefore have higher power consumption than
word striping (to be quantified),

       3)  Byte striping makes link deskew monitoring much more complex,
and requires unique initialization sequence to deskew fully,

       4) All of the above mean that testing of the byte-striped Hari will
be more difficult and yield will be lower (how much?) than for word

At the 10 G Fibre Channel meeting just this week, the byte striping
presentation included frank statements agreeing with the first three points
above (presented by the Hari group, not me!), and the logical conclusion of
these points is point number 4.  To me, this does not seem to be "a draw,"
it seems that word striping has considerable advantages for all concerned-
perhaps even those who have begun trying to design the byte striping
hardware.  The only plus of byte striping is lower latency, which is not
important for any of the proposed 10 Gb EN media options, since the added
latency is insignificant compared to even the shortest media latencies.
Could you please explain why you feel that the byte vs. word has come to a
"draw" ?

Mark B. Ritter
  Manager, Communication Link Design
  Room 36-107
  IBM T.J. Watson Research Center
  P.O. Box 218
  Yorktown Heights, NY.  10598
       phone: (914) 945-2170
       fax      :                  -1974
       dept. secretary   -3498

"DUGAN,RICHARD (HP-SanJose,ex1)" <richard_dugan@xxxxxxxxxxx> on
12/10/99 08:34:46 PM

Sent by:  owner-stds-802-3-hssg@xxxxxxxx

To:   "'stds-802-3-hssg@xxxxxxxx'" <stds-802-3-hssg@xxxxxxxx>
Subject:  Hari Byte vs. Word striping

Now that the dust has settled a bit, I would like to declare the match a
draw (at least from our point of view).  It seems that both sides have some
advantages and disadvantages, but as a serdes vendor we don't see any
knockout punch. There are other more difficult problems to be solved.

With that in mind, it seems like there is no compelling reason to change
from the original byte striped proposal.

- Regards,

Richard Dugan
Agilent Technologies