Fujitsu Corporation

Katsumi Sekine

Ryoichi Ishibashi

Toshimasa Fukui

A congestion relieving system in a communication system includes a local switch (62a) and a customer station including a network terminator (64a) connected to the local switch (62a) and plural data receiving/transmitting units (65) connected to the network terminator (64a) through buses (67D and 67U) conformable to a DQDB protocol. The local switch (62a) includes a congestion relieving signal generating unit for generating a congestion relieving signal when congestion is detected. The congestion relieving signal is inserted, as a request bit, into a request bit area in the cell having a format conformable to the DQDB protocol. The cell is then transmitted from the local switch (62a) through the network terminator (64a) to the data receiving/transmitting units (65), and each data receiving/transmitting unit (65), is restricted, under the DQDB protocol, to transmit data, when the data receiving/transmitting unit (65) receives the request bit.

Congestion relieving system in a communication system

One of a plurality of subscribers connecting via a communications line a signal line and switching units, each accommodating a subscriber line connected to a terminal, etc., lowers the communication quality of the communications to reduce the cost of communications. A calling or called subscriber issues to a switching unit an instruction to lower the communication quality. A control unit in one of the switching unit receives the instruction, analyzes a method of lowering the communication quality and determining a switching unit for performing it, generates a control signal indicating that the communication quality should be lowered, and sends via a signal line the control signal to the switching unit determined to be used for lowering the communication quality. After receiving the control signal, a polishing unit in that switching unit lowers the communication quality by discarding a part of communication contents of the communications according to the control signal, or lowering the priority of the communication contents. Thus, communications fees can be greatly reduced.

Bidirectional communication apparatus for reducing transmitted data

A congestion relieving system in a communication system includes a local switch (62a) and a customer station including a network terminator (64a) connected to the local switch (62a) and plural data receiving/transmitting units (65) connected to the network terminator (64a) through buses (67D and 67U) conformable to a DQDB protocol, the local switch (62a) includes a congestion relieving signal generating unit for generating a congestion relieving signal when congestion is detected. The congestion relieving signal is inserted, as a request bit, into a request bit area in the cell having a format conformable to the DQDB protocol. The cell is then transmitted from the local switch (62a) through the network terminator (64a) to the data receiving/transmitting units (65), and each data receiving/transmitting unit (65) is restricted, under the DQDB protocol, to transmit data, when the data receiving/transmitting unit (65) receives the request bit.

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Kawasaki, Japan

Katsumi Sekine