COMMUNICATION NODE, AND RING CONFIGURATION METHOD AND RING ESTABLISHMENT METHOD IN COMMUNICATION SYSTEM

• US 20090316588A1
• Filed: 06/30/2006
• Published: 12/24/2009
• Est. Priority Date: 06/30/2006
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Nakamura, Masato
• Granted Patent: US 7,983,177 B2
• Time in Patent Office: Days
• US Class Current: 370/249
• CPC Class Codes: H04L 12/437 Ring fault isolation or reconfiguration for SDH/SONET ring networks H04J3/085

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.

Claims

1-26. -26. (canceled)

27. A communication node that forms a communication system in which a plurality of communication nodes are connected in a ring, the communication nodes being one-to-one connected to each other by Ethernet (registered trademark) which is duplicated with a normal-system ring that transmits a frame when a communication state is normal and with a standby-system ring used for transmission of a frame when the communication state is abnormal, the communication node comprising:

a first port that includes an input unit for the normal-system ring and an output unit for the standby-system ring;

a second port that includes an output unit for the normal-system ring and an input unit for the standby-system ring; and

a communication processor that performs a process of receiving a frame input from the input unit of the normal-system ring in the first port and a process of transmitting the frame from the output unit of the normal-system ring in the second port upon normal communication, performs, when other communication node performs a loop-back process due to communication abnormality, only a process of forwarding a frame input from the input unit of the standby-system ring in the second port without receiving the frame and performs a process of transmitting the frame from the output unit of the standby-system ring in the first port, and, when communication abnormality occurs between the communication node and a neighboring communication node, performs the loop-back process by coupling between the normal-system ring and the standby-system ring of the port on the other side of the port connected to the neighboring communication node, 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.

28. The communication node according to claim 27, wherein the ring-establishment check-frame issuing unit of the communication processor includes a function of embedding specific information for uniquely identifying the frame in the ring-establishment check frame, wherein the communication processor further includes

a received-frame-information storage unit that stores received-frame information containing a source communication node of a ring-establishment check frame received from other communication node in the communication system and containing the specific information;

and

a received-frame-information management unit that compares the received-frame information acquired from the ring-establishment check frame sent by the other communication node with received-frame information corresponding to the other communication node stored in the received-frame-information storage unit, and, when the received ring-establishment check frame is the previously received frame, discards the frame.

29. The communication node according to claim 27, wherein the communication processor further includes

a loop-back-state control unit that controls, when a first neighboring communication node neighboring to the communication node is disconnected from the ring, to form a new ring by performing a loop-back process, and then, before a ring-establishment check process in the new ring is finished, a second neighboring communication node is added to a position of the first neighboring communication node, so that a communication node neighboring to the second neighboring communication node maintains the looped-back state until the ring-establishment check process in the new ring is finished.

30. The communication node according to claim 28, wherein the received-frame-information management unit of the communication processor further includes a function of acquiring received-frame information containing specific information for the ring-establishment check frame issued by the own communication node, of ring-establishment check frames passing around the standby-system ring, stores the acquired received-frame information in the received-frame-information storage unit when the same received-frame information is not stored in the received-frame-information storage unit, and discards the ring-establishment check frame when the same received-frame information is stored therein.

31. The communication node according to claim 27, wherein the communication processor further includes a frame discard processor that discards a frame of received frames except a ring-establishment check frame upon transition from a state in which a token frame is made to pass into the ring and communication is performed using a token passing system to a state of a ring-establishment check process due to disconnection of the neighboring communication node from the ring.

32. The communication node according to claim 27, wherein the ring-establishment check-frame issuing unit of the communication processor transits to a state of a ring-establishment check process when detecting reception of the ring-establishment check frame, and starts to issue a ring-establishment check frame.

33. The communication node according to claim 27, wherein the communication processor further includes a station-information management unit that issues, when the ring-establishment check process is finished, a station-information notification frame containing station information related to the own communication node required to create network configuration information, and that receives the station-information notification frame having circulated around the ring.

34. The communication node according to claim 33, wherein the station-information management unit of the communication processor is issuing a station-information notification frame until the issued station-information notification frame circulates around the ring and returns to the processor.

35. The communication node according to claim 34, wherein the station-information management unit of the communication processor further includes a function of embedding an issuance time of the frame in the station-information notification frame, and stopping issuing, when receiving the station-information notification frame having circulated around the ring, subsequent station-information notification frames, wherein the communication processor further includes

a frame-circulation-time calculating unit that calculates a frame circulation time by subtracting the issuance time in the station-information notification frame from a time of reception of the station-information notification frame which has been issued by the station-information management unit and has circulated around the ring;

and

a station-information notification-completion determining unit that determines whether any station-information notification frame passing around the ring is not detected for the frame circulation time or more after issuing of the station-information notification frame is stopped.

36. A ring-establishment check method in a communication system in which a plurality of communication nodes are connected in a ring, the communication nodes being one-to-one connected to each other by Ethernet (registered trademark) which is duplicated with a normal-system ring that transmits a frame when a communication state is normal and with a standby-system ring used for transmission of a frame when the communication state is abnormal, 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 to check whether a ring is established within the new ring, and, when receiving the issued ring-establishment check frame, stopping issuing a subsequent ring-establishment check frame; and

a ring-establishment checking step of recognizing that the ring is formed, 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 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 having circulated around the ring; 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.

37. The ring-establishment check method in the communication system according to claim 36, wherein

the ring-establishment-check-frame issuing step includes embedding specific information for uniquely identifying the frame in the ring-establishment check frame, and the ring-establishment check method further comprises:

a received-frame-information storing step of storing received-frame information containing a source communication node of a ring-establishment check frame received from other communication node in the communication system and containing the specific information; and

a received-frame-information managing step of comparing the received-frame information acquired from the ring-establishment check frame received from the other communication node with already stored received-frame information corresponding to the other communication node, and, when the received frame is the previously received frame, discarding the frame.

38. The ring-establishment check method in the communication system according to claim 36, further comprising:

in a communication node neighboring to a second communication node,

a loop-back controlling step of maintaining a state of a loop-back process until a ring-establishment check process in a new ring is finished, when a first communication node is disconnected from the ring, to configure the new ring by performing the loop-back process, and then, before the ring-establishment check process for the new ring is finished, the second communication node is added to a position of the first communication node.

39. The ring-establishment check method in the communication system according to claim 37, wherein the received-frame-information managing step further includes

performing processes of acquiring received-frame information containing specific information for the ring-establishment check frame issued by the own communication node, of ring-establishment check frames passing around the standby-system ring, storing the acquired received-frame information when the received-frame information for the acquired frame is not stored, and discarding the ring-establishment check frame when the received-frame information for the acquired frame is stored.

40. The ring-establishment check method in the communication system according to claim 36, further comprising a frame discard processing step of discarding a frame of received frames except the ring-establishment check frame, upon transition from a state in which a token frame is made to pass into the ring and communication is performed using a token passing system to the ring-establishment checking step of disconnecting a communication node from the ring and checking ring establishment.

41. The ring-establishment check method in the communication system according to claim 36, further comprising a station-information managing step of transmitting a station-information notification frame containing station information related to the own communication node required to create network configuration information, after the ring-establishment checking step.

42. The ring-establishment check method in the communication system according to claim 41, wherein the station-information managing step includes issuing station-information notification frame until the issued station-information notification frame circulates around the ring and returns.

43. The ring-establishment check method in the communication system according to claim 42, wherein the station-information managing step includes embedding an issuance time of the frame in the station-information notification frame, and stopping issuing, when receiving the issued station-information notification frame, subsequent station-information notification frames, and the ring-establishment check method further comprises:

a frame-circulation-time calculating step of calculating a frame circulation time by subtracting the issuance time in the station-information notification frame from a time of reception of the station-information notification frame which has been issued at the station-information managing step and has circulated around the ring; and

a station-information notification-completion determining step of determining whether station information is exchanged between communication nodes on the network when the station-information notification frame does not pass around the ring for the frame circulation time or more after issuing of the station-information notification frame is stopped.