Library /sys$common/syshlp/ncphelp.hlb LOOP, NODE, Example  *Conan The Librarian (sorry for the slow response - running on an old VAX)

      NCP>SET NODE TESTER CIRCUIT FZA-0
      NCP>LOOP NODE TESTER
      NCP>CLEAR NODE TESTER CIRCUIT

          The first command creates a loop node name (TESTER) for
          the associated circuit.  The second command initiates a
          node-level loopback test with the loop node name.  The
          third command removes the loop node name from the volatile
          database when the loopback is completed.