Fujitsu Corporation

Masamichi Kasa

Kazuhiro Uchida

Kazuyuki Tajima

Toshiyuki Sakai

Kazuto Nishimura

Hiroshi Tomonaga

Masatake Miyabe

Haruo Yamashita

Tomohiro Shinomiya

Akihiro Hata

Toshinori Koyanagi

Setsuo Abiru

Shinichi Shiwachi

Michihiko Goto

Manabu Tomiyasu

Masahiko Iwakiri

An apparatus for controlling buffering of an arrival packet. The apparatus includes a packet buffer for temporarily storing each of one or more packets to be transmitted in association with an arrival time thereof, and a packet discard section for determining an arrival packet to be discarded or to be stored in the packet buffer, based on a discard condition defined by using a packet residence time that is calculated on the basis of one or more residence times of one or more packets staying in the packet buffer, wherein the arrival packet is defined as a packet that has newly arrived at the apparatus.

Apparatus and method for controlling buffering of an arrival packet

A repeater stores retrieval situation of an address retrieved as an address identical with the transmission destination address of the reception frame in association with each address registered in the learning table, refers to, when the transmission source address of the received frame is registered in the learning table, the retrieval situation of the address stored in association with a port identical with the port that receives the frame from among retrieval situations, specifies an address to be overwritten by the transmission source address of the reception frame, overwrites and registers the transmission source address of the reception frame on the specified address, and updates, when the address identical with the transmission destination address of the received frame is retrieved from the learning table, the retrieval situation stored in association with the retrieved address.

Repeater and repeating method

A communication device capable of restraining the packet transmission efficiency from lowering. An address storing unit extracts, from uplink packets, the addresses of terminals connected to sub-units and registers the addresses in an address management table. An address extracting unit extracts the address of a destination terminal included in a downlink packet output from a layer 2 switch, and an address determining unit determines whether or not the address of the destination terminal is registered in the address management table. In accordance with the result of the determination, a packet output unit outputs the downlink packet to a corresponding coupler.

Host unit in a passive optical network

In a communication system comprising a network unit and a plurality of subscriber units connected to the network unit, the network unit generates a message in which validity of transmission grant information is set for the subscriber units, and suspends a transmission of polling information to allocate a transmission grant to the subscriber units by using the transmission grant information for a fixed time in consideration of a processing time of the subscriber units from a time when the message has been completely transmitted. Also, when a disconnection state of an inputted cell from the subscriber units is detected, the network unit may suspend an input disconnection detecting operation for a fixed time from a time when the message and the polling information have been completely transmitted. Furthermore, a switchover of an input disconnection detection/transmission grant information may be suspended by mutually exchanging messages.

Communication system

In a system where a plurality of terminal units are connected to a network unit via an optical transmission line and packets are transmitted in units of cells according to polling information, polling request information including the number of variable-length packets stored in the buffer of each of the terminal unit, the number of cells composing each variable-length packet and the number of remaining cells of a packet being read is created, polling information corresponding to a time slot allocated according to the polling request information is transmitted from the shared band control unit of the network unit, and bands are allocated to the plurality of terminal units.

Band allocation method and transmission system for transmitting variable-length packets

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Fukuoka, Japan

Masamichi Kasa