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Another example of doing this is the
hi_lfer variable used in 10GBASE-T, clause 55.
It counts FEC decoding failures. In my opinion, when the FEC is essential to the link integrity, counting errors or even specifying the BER prior to FEC is a waste of time (for a bunch of reasons, among them that if you want to translate you have to
assume a bunch of things about the distribution of errors which may not be true).
However, if you use the error-rate post-FEC for block-lock, you’ll get a much more stable result, and one that is easy to specify. George Zimmerman Principal, CME Consulting Experts in Advanced
PHYsical Communications Technology george@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx 310-920-3860 (PLEASE NOTE NEW EMAIL ADDRESS.
THE OTHER WILL STILL WORK, BUT PLEASE USE THIS FOR CME BUSINESS) From: Duane
Remein [mailto:Duane.Remein@xxxxxxxxxx] Below is the solution 802.3bn EPoC (D1.3) will be using to signal 64B/66B blocks which have bad FEC. This might be useful for your signaling across the AUI.
101.3.3.1.3 Codeword error monitor
The FEC decoder in the CNU shall provide a user-configurable option (variable
CRC40ErrCtrl) to indicate an uncorrectable FEC codeword (due to an excess of symbols containing errors) to higher layers. If
CRC40ErrCtrl is enabled and the calculated value of CRC40 does not match the value of CRC40 retrieved from the received FEC codeword, the FEC decoder replaces bit <0> and <1> in the sync headers in all 64B/ 66B blocks with the binary value of “11”. If
CRC40ErrCtrl is set to enable and the calculated value of CRC40 does not match the value of CRC40 retrieved from the received FEC codeword the FEC decoder indicates an error to the PCS by replacing bit <0> and <1> in the sync header with the binary value
of "11" in the first 64B/66B block and every 8th 64B/66B block, e.g. 1st, 9th, 17th, 25th, etc. as well as the last 64B/ 66B block from the errored FEC codeword. The BER monitor state machine as defined in Clause 49 is then disabled. This option is intended
for testing purposes. Best Regards, Duane FutureWei Technologies Inc. Director, Access R&D 919 418 4741 Raleigh, NC |