Hitachi, Ltd.

Other

Hitachi America, Ltd.

Shoichi Hanatani

Shigeki Kitajima

Hirohisa Sano

Tatsuo Kanetake

Masahiro Takatori

Yasuyuki Fukashiro

Yukio Hayashi

Hiroki Ikeda

An optical crossconnect apparatus which includes one terminal connected to a transmission path from one optical transmission terminal station and another terminal connected to a transmission path from another optical transmission terminal station, a first optical signal switch having 'M' ports and 'N' ports, through which the optical signal can pass, a second optical signal switch having &#x201c;M&#x201d; ports and &#x201c;N&#x201d; ports, through which the optical signal can pass, and &#x201c;L&#x201d; optical signal repeaters, one end connected to the &#x201c;N&#x201d; ports of the first optical signal switch, and the other end connected to the &#x201c;N&#x201d; ports of the second optical switch. The &#x201c;N&#x201d; and the &#x201c;N&#x201d; ports are equal to &#x201c;L&#x201d; optical signal repeaters. The &#x201c;M&#x201d; ports of the first optical signal switch connected to the one terminal, and the &#x201c;M&#x201d; ports of the second optical signal switch connected to the other terminal are larger than, or equal to 2.

Optical crossconnect apparatus and optical transmission system

A network is protected against interruption of service while one or more faulty switches or optical fiber transmission lines are repaired or replaced, by an interconnecting configuration of small N&#xd7;N optical input/output switches, where N is 2 or greater than 2. The switches are configured among protection and working transmission lines. The small number of fibers for each switch improves repair and installation connection reliability and permits configurations that flexibly meet differing requirements. Also the fault is monitored with a fault check signal.

Optical protection switching using 2 by 2 switching functions

An optical crossconnect apparatus which includes one terminal connected to a transmission path from one optical transmission terminal station and another terminal connected to a transmission path from another optical transmission terminal station, a first optical signal switch having &ldquo;M1&rdquo; ports and &ldquo;N1&rdquo; ports, through which the optical signal can pass, a second optical signal switch having &ldquo;M2&rdquo; ports and &ldquo;N2&rdquo; ports, through which the optical signal can pass, and &ldquo;L&rdquo; optical signal repeaters, one end connected to the &ldquo;N1&rdquo; ports of the first optical signal switch, and the other end connected to the &ldquo;N2&rdquo; ports of the second optical switch. The &ldquo;N1&rdquo; and the &ldquo;N2&rdquo; ports are equal to &ldquo;L&rdquo; optical signal repeaters. The &ldquo;M1&rdquo; ports of the first optical signal switch connected to the one terminal, and the &ldquo;M2&rdquo; ports of the second optical signal switch connected to the other terminal are larger than, or equal to 2.

Input/output fibers for the optical cross-connect system are classified into working fibers and protecting fibers. In a normal time (a state in which there occurs no failure), there turns out to be a one-to-one correspondence between a line terminal and a working fiber. Namely, connection property required for the switch matrix in the optical cross-connect system is not necessarily strictly non-blocking connections among all of the fibers. The connection property is a one-to-one connection relationship with the working fibers, and is a predetermined connection relationship with the protecting fibers at the time of a failure occurrence. Utilization thereof makes it possible to extremely downsize scale of the switch.

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Richardson, TX, United States of America

Shoichi Hanatani