Nec Corporation

Hitachi, Ltd.

Fujitsu Corporation

Nippon Telegraph and Telephone Corporation

Kenji Akutsu

Hiromi Ueda

Takatoshi Kurano

Yoshihiro Ashi

Yukio Nakano

Motoo Nishihara

Takafumi Chujo

Shigeo Amemiya

Ryuichi Ikematsu

In a monitor system in a digital communication apparatus including communication processing blocks on transmission paths of digital data, test data inserting units and data monitor units are arranged such that a monitor interval for the monitor operation in a block overlaps with a monitor period for the monitor operation between adjacent blocks in each processing block. As a result, there is no unmonitored interval in each processing block, thereby achieving a complete monitor operation.

Monitor system for digital communication apparatus

In an ATM switching network, ATM (asynchronous transfer mode) self-routing switches are interconnected by facilities carrying STM-N (synchronous transport modules level N) signals. At each inlet of an ATM self-routing switch, an STM overhead is removed from each frame of an incoming STM-N signal to create a vacant interval and the frame is converted according to ATM cell format into a series of data ATM cells, and an idle ATM cell is derived from the vacant interval. A supervisory bit sequence is inserted to the payload field of the idle ATM cell to produce a supervisory ATM cell, and the data and supervisory ATM cells are sent into the ATM switch. At each outlet of the switch, the bit sequence of the supervisory ATM cell is checked to evaluate the quality of the ATM switch and a series of data ATM cells is then converted into an STM-N signal according to STM-N frame format.

High throughput supervisory system for ATM switching systems

Growing community of inventors

Kanagawa, Japan

Kenji Akutsu