US 2010/0165998 A1Published application

Communication node, and ring configuration method and ring establishment method in communication system

AssigneeMitsubishi Electric Corporation

InventorMasato NAKAMURA

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Abstract

A plurality of communication nodes are one-to-one connected to each other by Ethernet (registered trademark) which is duplicated with a normal-system ring and with a standby-system ring. The communication node includes an A port, a B port, and a communication processor that performs a process of receiving a frame output from the B port and a process of transmitting the frame from the normal-system ring from the B port when the communication is normal. When other communication node performs a loop-back process due to communication abnormality, the communication node performs only a process of forwarding a frame input from the standby-system ring in the B port without receiving the frame and performs a process of transmitting the frame from the A port to the standby-system ring.

Claims17

Dependent claims

A communication node that forms a communication system in which a plurality of communication nodes are connected to each other in a ring by Ethernet (registered trademark), the communication node comprising:

a first port that includes an input unit that receives a frame and an output unit that outputs a frame;
a second port that includes an input unit that receives a frame and an output unit that outputs a frame;
and
a communication processor that performs a process of receiving a frame input from the input unit of the first port and transmits the frame from the output unit of the second port when the first port and the second port are respectively in normal states, performs, when communication abnormality occurs between the communication node and a neighboring communication node, a loop-back process being a process of receiving a frame input from an input unit of a port on the other side of a port connected to the neighboring communication node and transmitting the frame from an output unit of the same port as the input unit to which the frame has been input, and when other communication node performs the loop-back process, transmits the frame from the output unit of the first port without performing a process of receiving a frame input from the input unit of the second port, wherein
the communication processor includes
a ring-establishment check-frame issuing unit that issues a ring-establishment check frame in which an issuance time is embedded when power is turned on or when an own communication node performs a loop-back process to configure a new ring, and, when receiving the ring-establishment check frame having circulated around the ring, stops issuing a subsequent ring-establishment check frame;
a frame-circulation-time calculating unit that calculates a frame circulation time by subtracting the issuance time in the ring-establishment check frame from a time of reception of the ring-establishment check frame which has been issued by the ring-establishment check-frame issuing unit and has circulated around the ring;
and
a ring-establishment determining unit that determines whether any ring-establishment check frame passing around the ring is not detected for the frame circulation time or more after issuing of the ring-establishment check frame is stopped.

6 more elements

A ring-establishment check method in a communication system in which a plurality of communication nodes are connected to each other in a ring by Ethernet (registered trademark), the ring-establishment check method comprising:

a ring-establishment-check-frame issuing step of issuing, when power is turned on or when an own communication node performs a loop-back process by the communication node to configure a new ring, a ring-establishment check frame with an issuance time of the frame embedded therein, and, when receiving a ring-establishment check frame, stopping issuing a subsequent ring-establishment check frame;
and
a ring-establishment checking step of checking that the ring has been established, by receiving the ring-establishment check frame issued by the communication node at the ring-establishment-check-frame issuing step, wherein
the ring-establishment checking step includes
a frame-circulation-time calculating step of calculating a frame circulation time by subtracting the issuance time in the ring-establishment check frame from a time of reception of the ring-establishment check frame;
and
a ring-establishment determining step of confirming establishment of the ring when the ring-establishment check frame does not pass around the ring for the frame circulation time or more after issuing of the ring-establishment check frame is stopped.

4 more elements

Dependencies are inferred from the claim text.