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Re: [HSSG] BER Objective

For the 100 Mbps EFM fiber optic links (100BASE-LX10 and 100BASE-BX10)
we specified a BER requirement of 1E-12, consistent with the BER requirement
for gigabit links. We recognized that this would be impractical to test in a
production environment, so we defined a means to extrapolate a BER of 1E-12
by testing to a BER of 1E-10 with an additional 1 dB of attenuation.  See
58.3.2 and 58.4.2.
Howard Frazier
Broadcom Corporation

From: Roger Merel [mailto:roger@xxxxxxxxxxx]
Sent: Monday, August 28, 2006 1:54 PM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [HSSG] BER Objective



Prior to 10G, the BER standard (for optical communications) was set at 1E-10 (155M-2.5G).  At 10G, the BER standard was revised to 1E-12.  For unamplified links, the difference between 1E-12 and 1E-15 is only a difference of 1dB in power delivered to the PD.  However, the larger issue is one of margin and testability (as the duration required to reliably verify 1E-15 for 10G is impractical as a factory test on every unit) especially since we’d want to spec worst case product distribution at worst case path loss (cable+connector loss) and at EOL with margin.  Thus in reality, all products ship at BOL from the factory with a BER of 1E-15 and in fact nearly all will continue to deliver 1E-15 for their entire life under their actual operating conditions and with their actual cable losses.


Thus, if by “design target”, you mean a worst case-worst case with margin to be assured at EOL on every factory unit, then this is overkill.  I might be willing to entertain a 1E-13 BER as this would imply that same number of errors per second (on an absolute basis; irrespective of the number of bits being passed; this takes the same time in the factory as verifying 1E-12 at 10G although this is in fact a real cost burden which adversely product economics); however, this would not substantially change the reality of the link budget.  It would make for a sensible policy for the continued future of bit error rate specs (should their be future “Still-Higher-Speed” SG’s).






From: Martin, David (CAR:Q840)
Sent: Friday, August 25, 2006 12:22 PM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: BER Objective


During the discussion on Reach Objectives there didn’t appear to be any mention of corresponding BER.


Recall the comments from the floor during the July meeting CFI, regarding how 10GigE has been used more as infrastructure rather than as typical end user NICs. And that the application expectation for 100GigE would be similar.


Based on that view, I’d suggest a BER design target of (at least) 1E-15. That has been the defacto expectation from most carriers since the introduction of OC-192 systems.


The need for strong FEC (e.g., G.709 RS), lighter FEC (e.g., BCH-3), or none at all would then depend on various factors, like the optical technology chosen for each of the target link lengths.


David W. Martin
Nortel Networks
+1 613 765 2901 (esn 395)