RE: 1000BASE-T PCS question

["Chang, Edward S" <Edward.Chang@xxxxxxxxxx>]

Roy:

The BER of 10^-12 is specified in GbE Optical section, and Fibre Channel
specification.  They were originated from file transfer which need low BER
to avoid frequent retry which is times consuming, particularly for a file. 

Ed Chang

-----Original Message-----
From: Roy Bynum [mailto:rabynum@xxxxxxxxxxx]
Sent: Friday, May 28, 1999 9:09 PM
To: Chang, Edward S
Cc: Jaime Kardontchik; rtaborek@xxxxxxxxxxxxxxxx; HSSG_reflector
Subject: Re: 1000BASE-T PCS question


Edward,

Where did you get the requirement for a BER of 10^-12?  If native
Ethernet only has a BER of 10^-10 why exceed that?  On the carrier
systems we use what is known as forward error correction (FEC) to
achieve higher than 10^-10 BER or to achieve that at greater distances.

					Thank you,
					Roy Bynum


Chang, Edward S wrote:
> 
> Jami:
> 
> We have been discussing scramble code versus block code, 8B/10B in
> particular, for a while on the reflector. Many people have the same
feeling
> that scrambled code has run length much longer than desirable to cause
> base-line wander, and PLL clock drift; as a result, it can not meet the
BER
> of 10^-12
> 
> The SONET using scramble code has BER of 10^-10, which is not recommended
> for the datacom file transfer.  I believe the BER of 1000BASE-T is 10^-10,
> again, which is not recommended for file transfer.
> 
> You can prove the BER is 10^-12 for the 4D symbol code to enable it to be
> used for all purposes, or stay at 10^-10 BER to be used, as 802.3ab, for
> less critical data handling.
> 
> Please clarify.
> 
> Ed Chang
> Unisys Corporation
> Edward.Chang@xxxxxxxxxx
> 
> 
> -----Original Message-----
> From: Jaime Kardontchik [mailto:kardontchik.jaime@xxxxxxxxxxx]
> Sent: Wednesday, May 26, 1999 9:48 PM
> To: rtaborek@xxxxxxxxxxxxxxxx
> Cc: Jaime Kardontchik; HSSG_reflector
> Subject: Re: 1000BASE-T PCS question
> 
> Rich,
> 
> For simplicity, I did not mention nor I did include in the
> figures that the 4D encoded symbols are randomized before
> sending them to the transmitters. This procedure is described
> in the 1000BASE-T standard.
> 
> The produce assures that the output levels send down the
> wires (or the fiber) are DC balanced. However, you will not
> get the nice extremely short running disparity that one could
> get with the 8b/10b encoder, since the randomization is based
> on the scrambler. The scrambler used is 33 delays long (much
> longer than the scrambler used in Fast Ethernet) and it is
> expected to produce a better short term balance than the one
> obtained in Fast Ethernet.
> 
> The clock can be recovered (in the same way as it is recovered in
> Fast Ethernet). Many simulations were run during the development
> of the 1000BASE-T standard and presented during its meetings
> showing that this is the case. There is already a well known
> company that has 1000BASE-T transceivers on Silicon, and
> has shown that they work in the last Interop gathering.
> 
> Jaime
> 
> Jaime E. Kardontchik
> Micro Linear
> San Jose, CA 95131
> email: kardontchik.jaime@xxxxxxxxxxx
> 
> Rich Taborek wrote:
> 
> > Jaime,
> >
> > I have a question about the 4D 8-state Trellis code used by 1000BASE-T
> > which I hope you may be able to answer:
> >
> > Is the 4D 8-state Trellis code A DC balanced code? If not, how difficult
> > will it be for the receiver to recover the clock?
> >
> > P.S. I believe that the usual procedure for presentations is to send
> > them to the chair or webmaster for placement on the IEEE web site. In
> > this case, that means sending a copy to Jonathan Thatcher or David Law.
> > (I would send it to both of them).
> >
> > --
> >
> > Jaime Kardontchik wrote:
> > >
> > > Jonathan,
> > >
> > > I sent a couple of hours ago the complete presentation on the
> > > "10G-BASE-T" approach in pdf format, but I did not get it back from
the
> > > Reflector. The pdf file is not large (17 pages, about 70,000 bytes).
> > > Should I resend it ?
> > >
> > > Jaime
> > >
> > > Jaime E. Kardontchik
> > > Micro Linear
> > > San Jose, CA 95131
> > > email: kardontchik.jaime@xxxxxxxxxxx
> >
> > --
> >
> > Best Regards,
> > Rich
> >
> > -------------------------------------------------------------
> > Richard Taborek Sr.    Tel: 650 210 8800 x101 or 408 370 9233
> > Principal Architect         Fax: 650 940 1898 or 408 374 3645
> > Transcendata, Inc.           Email: rtaborek@xxxxxxxxxxxxxxxx
> > 1029 Corporation Way              http://www.transcendata.com
> > Palo Alto, CA 94303-4305    Alt email: rtaborek@xxxxxxxxxxxxx