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icon5.gif  What is the BER on copper ? How likely are problems ? [message #935 is a reply to message #930] Wed, 15 September 2004 19:40 Go to previous messageGo to previous message
Walter F.J. Müller is currently offline  Walter F.J. Müller
Messages: 229
Registered: December 2003
Location: GSI, CBM
first-grade participant

Error protection is certainly a good feature. The question is, how often do errors happen, how likely is a malfunction if there is no error protection ?

In the "Hardware" talk given by G. Kopcsay on the 2003 BlueGene/L workshop in Reno you'll find on page 17 some numbers for the serial links used in BlueGene/L. Bottom line is, that the BER is around 10-18.

If this is translated into an AS system with at 10 Tb/s thoughput, one gets roughly one bit error per day. About half will be caught by the coding layer, and with reasonable packet sizes less than 20% will be in the AS header, so there is a potential problem at the once every 2 week level.

If somebody has BER numbers for 2.5 Gbps links over 20-30" FR4 plus two connectors, which is a typical backplane scenario, please post a pointer to this information.

W.F.J.Müller, GSI, CBM, Tel: 2766
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