Library /sys$common/syshlp/nclhelp.hlb disable, routing, circuit, reachable_address  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    disable  [node node-id] routing circuit circuit-name -
             reachable address simple-name

    Example:

    disable routing circuit csmacd-1 reachable address to-bulean