Re: 1000BASE-T PCS question
- To: "Chang, Edward S" <Edward.Chang@xxxxxxxxxx>
- Subject: Re: 1000BASE-T PCS question
- From: Roy Bynum <rabynum@xxxxxxxxxxx>
- Date: Fri, 28 May 1999 20:08:39 -0500
- CC: Jaime Kardontchik <kardontchik.jaime@xxxxxxxxxxx>, rtaborek@xxxxxxxxxxxxxxxx, HSSG_reflector <stds-802-3-hssg@xxxxxxxx>
- Organization: .
- References: <8E37550684B3D211A20B0090271EC59D01818610@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
- Reply-To: rabynum@xxxxxxxxxxx
- Sender: owner-stds-802-3-hssg@xxxxxxxxxxxxxxxxxx
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.
Chang, Edward S wrote:
> 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
> -----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
> 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 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