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RE: 1000BASE-T PCS question

I'd like to clarify the residual BER spec for telecom systems. For OC-48
rate SONET systems, the
end-of-life BER customer requirement is 1E-12 (no FEC). For OC-192 rate the
value is the same, 
1E-12 without FEC (c.f. BCR GR-1377-CORE Section 4.2.1, page 4-3) and 1E-15
with FEC (customer

Note that some of our OC-48 customers, who have had systems running for up
to 10 years, are
measuring RBERs in the 1E-16 range (about one error every 7 years on a DS-3
trib). The OC-192
systems out there will need to run awhile longer to acquire similar
performance data.

The point here is that the SONET scrambler is not the limiting issue in
achieving low error rates. The
issue is having enough photons/bit, or optical SNR (eye-Q) to accurately
recover the data. 


David W. Martin
Nortel Networks
+1 613 765-2901   
+1 613 763-2388 (fax)

	-----Original Message-----
	From:	Chang, Edward S []
	Sent:	Thursday, May 27, 1999 9:16 AM
	To:	Jaime Kardontchik;
	Cc:	HSSG_reflector
	Subject:	RE: 1000BASE-T PCS question


	We have been discussing scramble code versus block code, 8B/10B in
	particular, for a while on the reflector. Many people have the same
	that scrambled code has run length much longer than desirable to
	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
	for the datacom file transfer.  I believe the BER of 1000BASE-T is
	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,
	less critical data handling. 

	Please clarify.

	Ed Chang
	Unisys Corporation