This enumerated value determines whether a port detected with a unidirectional link is shut down automatically by DLDP or must be shut down manually by an admin. Admins use auto(2), the default, in most environments so faulty links are immediately taken out of service, reserving manual(3) for situations where they want to review a detected fault before acting. Setting it to manual(3) means a port with a confirmed unidirectional link stays up until an admin explicitly disables it, rather than DLDP shutting it down automatically.