• The distance of a communications link measured by a tester with a TDR. For TIA/EIA 568-B.2, the Permanent Link is limited to 90 meters of horizontal cabling embedded in the walls and ceiling plenum. Length is one of the ANSI/EIA/TIA-568-B.2 required tests for a Category 5e UTP cable limited to a total distance of 100 meters including the Permanent Link of 90 meters + 10 meters allowance of line cords, patch cords and up to two cross-connects in a link. (also see NOMINAL VELOCITY OF PROPAGATION)