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Media Converter Glossary

  Media Converter Glossary

   Far End Fault

     The optional link integrity check on the 100BASE-FX fiber optic segments is called the Far End Fault function.
     In operation, Far End Fault detection occurs when a constant stream of IDLE symbols is no longer detected on
     a 100BASE-FX link. At this point, any device that detects the failure of the IDLE symbols on the receive side of
     the link will transmit a constant stream of Far End Fault signals. A device equipped with Far End Fault capability
     will interpret the incoming Far End Fault signals as a link failure and will be able to signal that failure to the
     management interface in the device.

     The Far End Fault detection feature is useful, since fiber links can be very long. A system that can detect a link
     that is working in one direction but not the other can save valuable time when troubleshooting links.

   Link Fault Pass Through

     When the link fault pass through function is enabled, the link status on the TX port will inform the FX port of
     the same device and vice versa. In the link fault pass through explanation shown below, if the link failure occurs
     on the TX port (1), the local FX port will send a non-idle pattern to notify the remote FX port (2). The remote
     FX port then forces its TX port to show a link failure, after receiving the non-idle pattern (4). This mechanism
     will alert the link fault status of the local TX port to the remote converter's TX port, and the link status of the
     remote TX port will show a fault. The link status LED will also shut off for both ports.

              (1) TP port link failed           (3) Fiber port gets remote  (5) Remote TP
                                                    link fault information      link is off

                                local                          remote
                          Converter A
Switch or PC  UTP                               Fiber Converter B UTP Switch or PC

                                                                            Link off

                          (2) Fiber port sends     (4) TP link fail
                              non-idle pattern

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