Nec Corporation

Toshiaki Arikawa

Michio Masuda

Shigekazu Harada

Takahide Sugita

Hidetoshi Shinoda

Ryuuichi Ikematsu

Motoo Nishihara

Kenshin Yamada

Hajime Ishikawa

Hajima Ishikawa

Disclosed are the multiplex communication system and the method therefore. A fault detection part of a duplex switching device detects it as generation of fault when recognizable signals are not detected from a connected line within a prescribed time. When the fault detection part detects the generation of fault in the present system line, the line switching part switches the lines from the present line to the standby line to perform communication between a terminal device and another terminal device therethrough. Also, the fault detection part notifies the generation of fault to the other duplex switching device after a prescribed switching protection time has passed from the time of the fault detected by the fault detection part, so the selection of the lines becomes consistent.

Optical transmission switching device

Multiplex communication system and method

A multi-layer class identifying communication apparatus, includes an input interface connected to input communication lines; a switch circuit; and an output interface connected to output communication lines. The input interface comprises an allocating section which determines a class identifier indicative of one of classes to which an IP packet belongs, from header data of the IP packet received through one of the input communication lines, and allocates an IP-QOS (Internet-Protocol-Quality-of-Service) code to the IP packet. The switch circuit selects one of the output communication lines based on a destination address of the IP packet, such that the IP packet is outputted from the output interface to the selected output communication output interface.

Multi-layer class identifying communication apparatus with priority control

In the packet scheduling device, the output class selection part is made to conduct the selective output of priority class, based on the weight count value calculated from a weight value corresponding to minimum guarantee bandwidth for each priority class and the amount of packet accumulated in each queue. The output class selection part operates so that if the weight count value is &ldquo;0&rdquo; or more, then the packet length of variable-length packet data to be output is subtracted from the current weight count value to give a renewed weight count value. On the other hand, if the weight count value is less than &ldquo;0&rdquo;, until reaching a predetermined repeat count (Cmax&minus;1), the weight value of each priority class is added to the weight count value of all priority classes, and, when reaching the repeat count (Cmax&minus;1), the weight value is added to the weight count value of all priority classes or replaced by half the weight value. Thereby, the weight count value is made to be more than &ldquo;0&rdquo;, and the values thus renewed are subject to the rule of round robin so as to select the priority class.

Packet scheduling device

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Tokyo, Japan

Toshiaki Arikawa