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RE: 9.584640

With regard to your point 5a below, I was pointing out that to do framing,
either flow control (because of coding overhead) OR new packet formating
(SDL ?)
would be required at that point, even at the slower OC-192 payload rate.  
I meant that this issue should be considered ALONG with the clocking issue.


  -----Original Message-----
  From: Rich Taborek [mailto:rtaborek@xxxxxxxxxxxxxxxx]
  Sent: Thursday, July 15, 1999 3:17 PM
  To: Hon Wah Chin; HSSG; Dan Dove
  Subject: Re: 9.584640

  Hon Wah,

  Thanks for kicking this issue off again!

      Hon Wah Chin wrote:

      >   ---
      >  :
      >  :

  In my conversations with several folks on both sides of the issue during
  Montreal meetings, I've come to the conclusion that the root reasons to
  either a 10 or 9.584640 Gbps are purely ease-of implementation based and
have no

  5) Consider a Ethernet to OC-192 line card (feeding a fiber or wavelength)
  operation. Assume that receive and transmit paths are separate on the
SONET side
  and related (i.e. full duplex) on the Ethernet side:
    a) Ethernet -> SONET @ 9.584640 Gbps: The Ethernet side can continuously
  the SONET link with no flow control required.
    b) Ethernet -> SONET @ 10 Gbps: The Ethernet side must be flow
controlled to
  prevent over-feeding the SONET link
    c) SONET -> Ethernet @ 9.584640 or 10 Gbps: The Ethernet side can
  source SONET data but will flow control or drop packets downstream
whenever the
  network is congested.


  Best Regards,


      > Given a raw continuous bit stream at the PMD, some scheme for
      > framing packets would be needed.  10M used a carrier, 100M used
      > 1000M used coding.  Using coding where the PMD speed is fixed at
      > would mean a further speed reduction (probably 10-20%) at the
      > interface. The discussion at the meeting has already started to
consider ways
      > of
      > reducing the useful throughput at the MAC/PLS below the data
clocking rate.
      > An
      > alternative framing scheme presented to HSSG, which has a smaller
      > reduction, requires a packet length header -- a departure from
previous 802
      > practice.
      >  :
      >  :
      > -hwc

  Richard Taborek Sr.    Tel: 650 210 8800 x101 or 408 370 9233
  Principal Architect         Fax: 650 940 1898 or 408 374 3645
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