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Barefoot/Edgecore Wedge100bf_32x no link over optical transport (not handling ethernet link fault signalling #521
We are connecting 100G ports with LR optics to a core router over optical transport (Juniper BTI). No issues getting link when directly connecting over short, direct patches , but over the transport we do not get Eth link unless we plugin Tx side of fiber patch first, wait a few seconds, then plugin Rx side.
It looks like the WEDGE switch is not reacting correctly to ethernet link fault signalling. When the device receives a 'remote fault' signal on an Rx port, it seems to stop transmitting ethernet signaling on its Tx port. It does not disable the Tx laser and we are assuming it's just transmitting CW (constance wave). Per the standards, the switch should not shutoff it's signalling, its Tx signal has to go to the far end device at which point that device would stop transmitting remote fault.
As to why it works over short spans and not via the optical transport: typically if you are connected directly to a device, the Tx from the WEDGE switch would hit the adjacent device fairly quickly, clearing the fault, so we think it comes down to the timing of the control loop on the switch monitoring the faults. When connected to any sort of optical transport, the linkup process takes a bit longer, which we believe is exposing the problem.