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Link Fault Pass-Through

Link Fault Pass-Through

| 1/13/2015 12:00:00 AM

Link Fault Pass Through, LFPT,  is a troubleshooting feature that combines TX LinkLoss (Twisted Pair, copper interface) and FX LinkLoss (Fiber, fiber interface) from both the local and remote IMC Networks media converters, when used in pairs.  This feature, when enabled, will pass a link fault through the device at each segment.  If a link fails on one interface of the media converter, the media converter will force the link down on its link partner and then forward it to the next interface.  The fault will be carried onto the local end.  LFPT can be enabled via DIP Switches or through SNMP management (if the product supports it).  
Media Converters, LFPT
If a fault should occur on the fiber (Segment 2) without LFPT enabled, both switches would display an active link on the fiber interfaces of the media converters even though a link has failed between the two.  Since neither switch would sense a failed link, they would not extinguish the LED on their copper interfaces. 
 
When LFPT is enabled through SNMP management, and a fault occurs on the fiber segment (Segment 2), both media converters would pass that fault through to the next segment.  Media converter 1 would force the copper segment 1 down which switch 1 would sense, and it would issue a Trap.  Media converter 2 would force the copper [CAT5] segment 3 down, which switch 2 would sense, and it would issue a Trap.  The SNMP server would receive the Traps and take the appropriate actions to help remedy the issue (usually by sending an alert to the network administrator). 
 
LFPT is a diagnostic feature that many network administrators require in media converter devices, in order to reduce troubleshooting and down time in a network application. If a single fault occurs, all Link LEDs will extinguish, and the network admin will investigate, fix and verify that all links are active before the customer may realize a down condition. 
 

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