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When connecting two devices via a pre-built system of patch panels, it mut must be taken into account the number of permanent links (segments of multi fiber cable, with patch panels at both ends) used.
If the number of permanent link is even (2,4,...) then you can employ standard "A to B" patch cables all the way. If the number of permanent link is odd (1,3,...) then you have to use one "A to A" patch cable along the path. Even if it is not important where this cable is used, it is good to always adopt the same method, for example by placing the "A to A" cable on the last connection.
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