Network relay system and control method thereof

Abstract

The network relay device of the invention carries out data transmission to and from an opposite device to relay data in a network. The network relay device includes: multiple ports connecting with corresponding multiple ports of the opposite device via multiple links; and a link aggregation control module that aggregates the multiple links to establish a link aggregation, which is regarded as one logic link, and carries out transmission of a control frame signal including a synchronization bit, as well as data transmission, at each port via the link aggregation. In response to detection of occurrence of a trouble in at least one of the aggregated multiple links, the link aggregation control module causes a port that connects with a normal link without the trouble among the multiple ports to stop the data transmission and send the control frame signal including the synchronization bit set equal to a first value. Here the first value functions to stop the data transmission at a corresponding port of the opposite device connecting with the normal link.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a network relay device that carries out data transmission to and from an opposite device, so as to relay data in a network. [0003] 2. Description of the Related Art [0004] A switch as one of network relay devices may be designed to have the function of link aggregation, which connects with another switch by multiple links (multiple physical lines) and aggregates the multiple links as one logic link. [0005] One known example of the link aggregation is disclosed in Japanese Patent Laid-Open Gazette No. 2002-26909. [0006] The bandwidth of the logic link is the total of the individual bandwidths of the aggregated multiple links. The link aggregation thus advantageously expands the bandwidth. Even in the case of the occurrence of a trouble or failure in some of the aggregated multiple links, the link aggregation adopts a degenerate mode to continue communication via the remaining normal l...

AI Technical Summary

Benefits of technology

[0013] The object of the invention is thus to eliminate the drawbacks of the prior art technique and provide a technique of restraining a degenerate mode and stopping data transmission via aggregated multiple links, in the case of the occurrence of a trouble or failure in at least one of the aggregated multiple links.

[0025] The link aggregation control module allows for a transition of the operating state from the first state to the second state, in response to detection of occurrence of a trouble in a link other than a link connecting with the port in the first state, among the aggregated multiple links. The link aggregation control module allows for a transition of the operating state from the second state to the third state, when the port in the second state receives the control frame signal from a corresponding port of the opposite device. The link aggregation control module allows for a transition of the operating state from the third state to the fourth state, in response to recovery of the link from the trouble. The link aggregation control module allows for a transition of the operating state from the fourth state to the first state, when the port in the fourth state receives the control frame signal including the synchronization bit set equal to 1 from a corresponding port of the opposite device. The link aggregation control module allows for a transition of the operating state from the first state to the fourth state, when the port in the first state receives the control frame signal including the synchronization bit set equal to 0 from a corresponding port of the opposite device.

[0026] In response to the occurrence of a trouble or failure in at least one of the aggregated multiple links, the second network relay device of the invention causes the port connecting with the normal link without the trouble to change the operating state from the first state to the second state. The port in the second state stops the data transmission and sends the control frame signal including the synchronization bit set equal to 0 to the opposite device, in order to stop the data transmission at the corresponding port of the opposite device. The second network relay device of the invention thus effectively restrains the degenerate mode and stops the data transmission via the aggregated multiple links, in the case of the occurrence of a trouble or failure in at least one of the aggregated multiple links.

[0027] In one preferable embodiment of the second network relay device of the invention, the link aggregation control module allows for the transition of the operating state from the third state to the fourth state, when the trouble has been fixed in the link and when all the multiple ports have received the control frame signal including the synchronization bit set equal to 1 from respective corresponding ports of the opposite device.

Problems solved by technology

This prior art technique, however, has the following problems with regard to the redundancy of the link aggregation.

In the case of the occurrence of a trouble in some of the aggregated multiple links, the degenerate mode establishes communication by only normal links and thus undesirably reduces the total bandwidth by the bandwidth of the link with the trouble.

This problems is not restricted to the switches as one of the network relay devices but is also found in other network relay devices having the function of link aggregation, for example, routers.

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