Hitachi, Ltd.

Mitsunobu Kimura

Takashi Mori

Masaki Ohira

Koji Kato

Masazumi Noguchi

Masatoshi Takahashi

Keiji Usuba

Seigo Obayashi

A transmission speed of a protection (backup) line using 1G-OLT unit and 1G-ONU unit is set to be lower than a transmission speed of a working (primary) line using 10G-OLT unit and 10G-ONU unit. A priority and band of each communication service in ONU are preset individually and separately every LLID for a working (primary) line and a protection (backup) line. When bands are allocated to the protection (backup) line, the band allocation is performed so as to secure a minimum number of bands of each communication service. A monitoring controller refers to a predetermined band information table according to an operation state of the working (primary) line or the protection (backup) line with respect to a downstream signal packet.

Passive optical network system and optical line terminal

In a transmission network including multiplex transmission units A, F, G, D and E, when the line breakage has occurred on the OC-12 transmission path of the direction from unit A to unit F, the unit F detects the signal coming in from the OC-12 path indicative of the line breakage. The unit F inserts the APS bytes which comes in from the unit A into the undefined area of the OC-192 transport overhead which is reserved for the through-transport of APS bytes, and transports it to the unit G. On receiving the through-transport APS bytes, the unit G inserts it intact into the defined area for the APS bytes in the OC-12 transport overhead, and sends it to the unit D. In this manner, protection switching between the units A and D is carried out.

Method and apparatus for multiplex transmission

A bi-directional line switched ring network system including a plurality of optical fiber communications lines and a plurality of nodes connected by the plurality of optical fiber communications lines forming a closed circuit. Each of the nodes performs an addition and a drop of a path between an external communications apparatus and the optical fiber communications lines or permits the path on the optical fiber communications lines to pass through, or performs a change of a direction of the path. A control unit is located in each of the nodes to control the addition, the drop, the pass-through and the direction change of the path. When the path passes through each of the nodes, the control unit sets a time slot number of the path in being inputted into the node and a time slot number of the path in being outputted from the node independently of each other.

Bi-directional line switched ring network system

Growing community of inventors

Fujisawa, Japan

Mitsunobu Kimura