Aspects of the present disclosure relates to an indexing terminal including a multi-fiber ruggedized de-mateable connection location, a first single-fiber ruggedized de-mateable connection location and a second single-fiber ruggedized de-mateable connection location. The multi-fiber ruggedized de-mateable connection location includes a plurality of fiber positions with one of the fiber positions optically coupled to the first single fiber ruggedized de-mateable connection location.

A master unit configured to manage a plurality of remote units connected in a ring topology, the master unit comprising: a network management section configured to transmit at least one of a path-state monitoring control signal and a delay measurement control signal to the plurality of remote units in a first direction and a second direction which is a reverse direction of the first direction, and receives an acknowledgement signal in response to the at least one of a path-state monitoring control signal and a delay measurement control signal; and switching control means for transmitting a forward signal received from a base station in the first direction, and transmitting a switching control signal in the second direction when a defect is detected in any remote unit among the plurality of remote units by the network management section.

A relay method includes transmitting, by a first apparatus in a ring network, a first control frame in which information of the first apparatus is stored, through a first port different from a second port where a communication failure is detected; receiving, by a second apparatus in the ring network, the first control frame through a third port, when the communication failure does not occur at a side of a fourth port different from the third port: storing information of the second apparatus in the first control frame; and transmitting the first control frame through the fourth port; and when the communication failure occurs at the side of the fourth port, determining whether a data frame flowing into the ring network is affected by the communication failure for every VLAN (virtual local area network) based on the first control frame; and switching a communication path set in an affected VLAN.

A master unit configured to manage a plurality of remote units connected in a ring topology, the master unit comprising: a network management section configured to transmit at least one of a path-state monitoring control signal and a delay measurement control signal to the plurality of remote units in a first direction and a second direction which is a reverse direction of the first direction, and receives an acknowledgement signal in response to the at least one of a path-state monitoring control signal and a delay measurement control signal; and switching control means for transmitting a forward signal received from a base station in the first direction, and transmitting a switching control signal in the second direction when a defect is detected in any remote unit among the plurality of remote units by the network management section.

An object of the present invention is to provide an optical access network that has high reliability for supporting information communication services and efficiently responds to difficult-to-predict optical fiber demand. An optical access network configuration according to the present invention includes an optical fiber cable 11 that is looped to connect a wiring section 25 and an exchange office 10 together (hereinafter, an upper loop), an optical fiber cable 21 that is looped and laid in each wiring section 25 (hereinafter, a lower loop), and an optical fiber switching function unit 31 installed at a connection point 30 between the upper loop 11 and the lower loop 21. The optical fiber switching function unit 31 is a wiring board or an optical switch which can be switched by connector connection. The wiring board or the optical switch may be remotely controllable.