Communication device and communication control method

Abstract

This communication device comprises a plurality of communication packages, a control unit, and a notification unit. The plurality of communication packages transmit and receive signals to and from the counterpart devices to be communicated via each of different links constituting a link aggregation. The control unit controls the execution and cancellation of a cold standby for each of the communication packages. When execution of a cold standby has been determined for a communication package by the control unit, the notification unit notifies the counterpart device before the communication package transitions to the cold standby state that the communication package is in a communication-disabled state. Meanwhile, when cancellation of a cold standby has been determined for a communication package by the control unit, the notification unit notifies the counterpart device after the communication package transitions from the cold standby state to an operational state that the communication package is in a communication-enabled state.

Description

Communication device and communication control method 【0001】 The present invention relates to a communication device and a communication control method. 【0002】 A conventional communication system has a communication device and its opposing device. The communication device is equipped with a communication PKG (package). The communication PKG can perform cold standby (see, for example, Patent Document 1). Cold standby means that when a redundant communication PKG is installed in the communication device, the power supply of the standby communication PKG is stopped and it is put on standby. By using the cold standby function to stop the power supply of some communication PKGs, reduction of power consumption is achieved. 【0003】 Japanese Patent Application Laid-Open No. 2020-110016 【0004】 In a communication device with a redundant configuration having a plurality of communication PKGs, the power consumption of the entire communication device is high. Therefore, in some cases, the power consumption of the entire device is reduced by cold-standby of some communication PKGs as described above. The communication device determines by itself whether to perform and release the cold standby of the communication PKG. Therefore, the communication device cannot cooperate with the opposing device, which is another communication device in the surroundings, and there is a possibility that communication frames are lost. 【0005】 In view of the above circumstances, an object of the present invention is to provide a communication device and a communication control method capable of reducing packet loss associated with the implementation and release of cold standby of a communication PKG. 【0006】A communication device according to one aspect of the present invention comprises: a plurality of communication packages that transmit and receive signals with a counterpart device via different links constituting a link aggregation; a control unit that controls the implementation and release of cold standby for each of the communication packages; and a notification unit that, when the control unit decides to implement cold standby for the communication package, notifies the counterpart device that the communication package is in a communication-unavailable state before the communication package transitions to a cold standby state, and when the control unit decides to release cold standby for the communication package, notifies the counterpart device that the communication package is in a communication-available state after the communication package transitions from a cold standby state to an operational state. 【0007】 A communication control method according to one aspect of the present invention includes a control step of controlling the implementation and release of cold standby for each of a plurality of communication packages that transmit and receive signals with a counterpart device via each of the different links constituting a link aggregation; a notification step of notifying the counterpart device that the communication package is in a communication-unavailable state before the communication package transitions to a cold standby state when it is decided in the control step to release the cold standby for the communication package when it is decided in the control step to notify the counterpart device that the communication package is in a communication-available state after the communication package transitions from a cold standby state to an operational state. 【0008】 The present invention makes it possible to reduce packet loss associated with the implementation and deactivation of cold standby for communication packages. 【0009】 This is a diagram illustrating the overview of the communication system according to this embodiment. This is a diagram showing the configuration of the communication system according to the same embodiment. This is a diagram showing the configuration of the communication package according to the same embodiment. This is a sequence diagram showing the operation of the communication system according to the same embodiment. This is a sequence diagram showing the operation of the communication system according to the same embodiment. This is a sequence diagram showing the operation of the communication system according to the same embodiment. 【0010】 Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a diagram illustrating the outline of this embodiment. The communication system 1 includes a counterpart device 2 and a communication device 3. The counterpart device 2 is another communication device that communicates with the communication device 3. The communication device 3 is equipped with N (where N is an integer of 1 or more) communication packages 31. The communication device 3 is capable of autonomously implementing and deactivating cold standby for each of the communication packages 31 it is equipped with. 【0011】 When the communication package 31 enters cold standby mode, communication between the opposing device 2 and the communication package 31 goes down. Therefore, in conventional technology, frame loss occurs, albeit for a short time. Also, when cold standby is released, it may take time for the communication package 31 to start up. For example, it may take several minutes before frame transmission is possible between the opposing device 2 and the communication package 31. If the opposing device 2 determines that the link is up and sends a frame to the communication package 31 during that time, frame loss will occur. 【0012】 Therefore, in this embodiment, the objective device 2 is prevented from transmitting frames to the communication PKG 31 while it is in cold standby mode, with no changes to the objective device 2, or with as few changes as possible. Specifically, the communication device 3 notifies the objective device 2 whether or not the communication PKG 31 is in cold standby mode. Upon receiving this notification, the objective device 2 refrains from transmitting frames to the communication PKG 31 while it is in cold standby mode, and transmits frames only to the communication PKG 31 that is in operation. This control prevents frame loss of transmitted frames from the objective device 2. 【0013】 According to this embodiment, even if the communication device 3 autonomously puts the communication package 31 into cold standby mode, the loss of user traffic can be suppressed. Therefore, power consumption can be reduced by putting the communication package 31 into cold standby mode while maintaining service quality. 【0014】 Figure 2 shows an example of the configuration of communication system 1. Communication system 1 includes a counterpart device 2 and a communication device 3. 【0015】The opposing device 2 has N first ports 21, one or more second ports 22, a transfer unit 23, and a control unit 24. 【0016】 Each first port 21 is connected one-to-one by cable to a communication package 31 installed on the communication device 3. The N first ports 21 of the opposing device 2 and the N communication packages 31 of the communication device 3 form a link aggregation (LAG). Link aggregation is a function that treats multiple physical links as a single logical link. The N first ports 21 are denoted as first ports 21-1 to 21-N. The opposing device 2 may have (N+1) or more first ports 21. The second port 22 is connected by cable to other communication devices. 【0017】 The transfer unit 23 outputs the signal received from the first port 21 from the second port 22 according to the signal destination, etc. Also, the transfer unit 23 outputs the signal input from the second port 22 from the first port 21 according to the signal destination, etc. 【0018】 The control unit 24 controls whether transmission from each first port 21 is possible or not, based on the notification of the status of the communication PKG 31 received from the communication device 3, similar to the conventional technology. The control unit 24 also controls the transfer unit 23 so as not to transmit frames from first ports 21 that are in a state where frame transmission is not possible. The control unit 24 may be provided inside the transfer unit 23. 【0019】 The communication device 3 is equipped with N communication packages 31 and a control package 39. The N communication packages 31 are connected to the opposing device 2 via each of the N different links that constitute the link aggregation. The communication package 31 connected to the first port 21-n (where n is an integer between 1 and N) of the opposing device 2 is referred to as communication package 31-n. 【0020】The communication package 31 has a connection port connected to a link with a lower-level device and a connection port connected to a link with a higher-level device. The communication package 31 outputs signals received from the link with the lower-level device to the link with the higher-level device, and outputs signals received from the link with the higher-level device to the link with the lower-level device. In the following, the opposing device 2 is considered to be a higher-level device of the communication device 3, but the opposing device 2 may be a lower-level device of the communication device 3. The communication package 31 has two states: an operational state and a cold standby state. The operational state is a state in which the communication device 3 can transfer frames to a lower-level device, and the cold standby state is a state in which the communication device 3 cannot transfer frames to a lower-level device. Note that the operational state and the cold standby state may each have further subdivided states. 【0021】 Each communication package 31 has a notification unit 32. The notification unit 32 of a communication package 31-n is referred to as notification unit 32-n. The notification unit 32-n communicates to the opposing device 2 that the communication package 31-n is in a state where it cannot receive communication frames. In other words, the notification unit 32-n notifies the opposing device 2 of the frame reception failure state before the communication package 31-n transitions to a cold standby state after receiving instructions from the control package 39. Furthermore, the notification unit 32-n notifies the opposing device 2 of the frame reception failure state after the communication package 31-n transitions from a cold standby state to an operational state after receiving instructions from the control package 39. 【0022】 The control PKG 39 determines whether to implement or cancel cold standby for each communication PKG 31. If the control PKG 39 determines that cold standby is being implemented for a communication PKG 31, it instructs that communication PKG 31 to transition from the operational state to the cold standby state. Also, if the control PKG 39 determines that cold standby has been canceled for a communication PKG 31, it instructs that communication PKG 31 to transition from the cold standby state to the operational state. 【0023】Communication device 3 controls communication PKG 31, which is the destination for frame transmission from the opposing device 2, by controlling the link state with the opposing device 2. Before communication PKG 31-n enters a cold standby state, communication device 3 notifies the opposing device 2 that frame transmission is not possible and blocks the port of communication PKG 31-n to bring the link down. While communication PKG 31-n is releasing from cold standby, communication device 3 keeps the port of communication PKG 31-n blocked and continues the link down. When communication PKG 31-n finishes releasing from cold standby and releases the port block on communication PKG 31-n to bring the link up, communication device 3 notifies the opposing device 2 that frame transmission is possible. 【0024】 Figure 3 shows an example configuration of the communication package 31. The communication package 31 includes an upper-level connection port 33, a lower-level connection port 34, a transfer unit 35, a CPU (central processing unit) 36, and a power supply 37. 【0025】 The upper-level connection port 33 is connected to the link with the first port 21 of the opposing device 2. The lower-level connection port 34 is connected to the link with the lower-level communication device. The transfer unit 35 outputs frames received by the lower-level connection port 34 from the upper-level connection port 33. The transfer unit 35 also outputs frames received from the upper-level connection port 33 from the lower-level connection port 34. 【0026】 The CPU 36 controls each part of the communication package 31. The CPU 36 also operates as a notification unit 32. The power supply 37 supplies power to the upper-level connection port 33, lower-level connection port 34, transfer unit 35, and CPU 36 of the communication package 31. Each of these parts operates using the power supplied by the power supply 37. 【0027】With the above configuration, the communication device 3 receives uplink frames from the lower connection port 34. The transfer unit 35 outputs the received uplink frames from the upper connection port 33. The communication device 3 also receives downlink frames from the upper connection port 33, which is connected to the opposing device 2. The transfer unit 35 outputs the received downlink frames from the lower connection port 34, which is connected to the lower communication device. In this way, uplink frames flow from the lower connection port 34 to the upper connection port 33 via the transfer unit 35, and downlink frames flow from the upper connection port 33 to the lower connection port 34 via the transfer unit 35. 【0028】 When the communication package 31 is released from cold standby, it turns on the power supply 37. The power supplied from the power supply 37 powers up the transfer unit 35 first, then the CPU 36, and finally the upper-level connection port 33 and the lower-level connection port 34 in that order. This order is because the upper-level connection port 33 and the first port 21 of the opposing device 2 are connected by a cable, so when the upper-level connection port 33 is powered up, a physical link is established between it and the opposing device 2. For example, if the upper-level connection port 33 is powered up first, the opposing device 2 will send a downlink frame to the communication package 31 because the link has been established, regardless of whether other components in the communication device 3 have already powered up. However, if other components of the communication package 31 are powered up, the frame received from the opposing device 2 will be discarded. 【0029】 Similarly, when performing cold standby, if the upstream connection port 33 is the last to receive power, the opposing device 2 may send an uplink frame to the communication package 31 even though all other components of the communication device 3 are powered off. In this case, the frame received by the communication package 31 from the opposing device 2 is discarded. 【0030】The communication package 31 keeps the upper-level connection port 33 blocked while cold standby is being released, starts up the CPU 36 and the transfer unit 35, and finally starts up the upper-level connection port 33 and the lower-level connection port 34. This prevents frames from being sent from the opposing device 2 until the communication package 31 is started up. In addition, when the communication package 31 performs cold standby, it first cuts off power to the upper-level connection port 33. 【0031】 Hereinafter, the upper-level connection port 33, lower-level connection port 34, transfer unit 35, CPU 36, and power supply 37 of the communication PKG 31-n will be referred to as upper-level connection port 33-n, lower-level connection port 34-n, transfer unit 35-n, CPU 36-n, and power supply 37-n, respectively. 【0032】 Next, an example of the operation of communication system 1 will be explained. Communication system 1 uses control frames transmitted from communication device 3 to control the destination of frames transmitted from opposing device 2. 【0033】 Figure 4 is a sequence diagram showing an example of the operation of communication system 1. The opposing device 2 and each communication PKG 31-n of communication device 3 perform the operations shown in Figure 4. Figure 4 is an example using IEEE (Institute of Electrical and Electronics Engineers) 802.3ad LACP (Link Aggregation Control Protocol). The communication PKG 31 of the opposing device 2 and communication device 3 notify the opposing device 2 of the status of the communication PKG 31 by sending and receiving LACP Data Unit (LACPDU) frames. 【0034】The communication PKG 31 of the opposing device 2 and the communication device 3 can be in one of the following states: DETACHED, WAITING, ATTATCHED, COLLECTING, or DISTRIBUTING. DETACHED means that it is not yet known which LAG the port should be associated with. WAITING means that the port is waiting to be coupled with the LAG. ATTATCHED means that the port and LAG are coupled, but frame transmission and reception are not possible. COLLECTING means that frame reception is possible, but frame transmission is not possible. DISTRIBUTING means that frame transmission and reception are possible. The communication system 1 prevents the opposing device 2 from transmitting a frame when the communication PKG 31 is in a state other than DISTRIBUTING. 【0035】 The first port 21-n of the opposing device 2 and the communication package 31-n of the communication device 3 are in the DISTRIBUTING state (steps S101, S102). The state of the first port 21-n is the state of communication with the communication package 31-n in the opposing device 2. The control unit 24 of the opposing device 2 outputs a LACPD DU frame with state information indicating that the first port 21-n is in the DISTRIBUTING state. The transfer unit 23 transmits the LACPD DU frame from the first port 21-n (step S103). The transfer unit 35-n of the communication package 31-n of the communication device 3 outputs the LACPD DU frame received by the upstream connection port 33-n to the CPU 36-n. Based on the state information set in the LACPD frame, the CPU 36-n keeps the communication package 31-n in the DISTRIBUTING state. 【0036】 Furthermore, the notification unit 32-n of the communication package 31-n outputs a LACPD DU frame to the transfer unit 35-n, which contains status information indicating that the status of the communication package 31-n is DISTRIBUTING. The transfer unit 35-n transmits the LACPD DU frame from the upper-level connection port 33-n (step S104). The transfer unit 23 of the opposing device 2 outputs the LACPD frame received by the first port 21-n to the control unit 24. Based on the status information set in the LACPD frame, the control unit 24 keeps the first port 21-n in the DISTRIBUTING state. 【0037】 The control PKG 39 of the communication device 3 determines that it will perform cold standby for the communication PKG 31-n (step S105). Before setting the state of the LACPDU of the communication PKG 31-n to cold standby, the control PKG 39 sets it to the ATTATCHED state. As a result, the notification unit 32-n of the communication PKG 31-n transmits the LACPDU, which has set state information indicating COLLECTING=False (frame reception impossible), to the opposing device 2 via the transfer unit 35-n from the upper-level connection port 33-n (step S106). Note that the WAITING state or DETACHED state may be used instead of the ATTATCHED state. 【0038】 The control unit 24 of the opposing device 2 receives the LACPD frame received by the first port 21-n via the transfer unit 23. Since the state information set in the received LACPD indicates COLLECTING = False, the control unit 24 transitions the state of the first port 21-n from the DISTRIBUTING state to the COLLECTING state according to the LACPD specifications (step S107). Since COLLECTING is a state where transmission is not possible, the opposing device 2 stops transmitting frames to the communication PKG 31-n (step S108). 【0039】 Meanwhile, after the transmission of the LACPDU frame in step S106, the control PKG 39 of the communication device 3 puts the communication PKG 31-n into a cold standby state and brings down the link between the upper-level connection port 33-n and the opposing device 2 (step S109). The power supply 37-n of the communication PKG 31-n stops supplying power to each part. 【0040】 After step S109, the control PKG 39 determines to release the cold standby state of the communication PKG 31-n (step S110). The control PKG 39 transitions the communication PKG 31-n to the operational state. The communication PKG 31-n begins supplying power sequentially from the power supply 37-n to the transfer unit 35-n, CPU 36-n, upper-level connection port 33-n, and lower-level connection port 34-n. Each of these units starts up with the supplied power, and the communication PKG 31-n transitions to the operational state (step S111). 【0041】After the communication PKG31-n transitions to the operating state, the control PKG39 causes the LACP state of the communication PKG31-n to transition to COLLECTING. The notification unit 32-n of the communication PKG31-n transmits an LACPDU in which state information indicating COLLECTING = True (frame reception enabled) is set from the upper connection port 33-n to the opposing device 2 via the transfer unit 35-n (step S112). The control PKG39 of the communication device 3 causes the state of the communication PKG31-n to transition to the DISTRIBUTING state (step S113). 【0042】 The control unit 24 of the opposing device 2 receives the LACPD frame received by the first port 21-n via the transfer unit 23. Since the state information set in the received LACDP indicates COLLECTING = True, the control unit 24 causes the state of the first port 21-n to transition from COLLECTING to the DISTRIBUTING state (step S114). 【0043】 The control unit 24 of the opposing device 2 transmits an LACPDU frame in which state information indicating DISTRIBUTING is set from the first port 21-n via the transfer unit 23 (step S115). The transfer unit 35-n of the communication PKG31-n mounted on the communication device 3 outputs the LACPDU frame input from the upper connection port 33-n to the CPU 36-n. Based on the state information set in the LACPD frame, the CPU 36-n keeps the communication PKG31-n in the DISTRIBUTING state. 【0044】 The notification unit 32-n of the communication PKG31-n transmits an LACPDU frame in which state information indicating DISTRIBUTING is set from the upper connection port 33-n to the opposing device 2 via the transfer unit 35-n (step S116). The control unit 24 of the opposing device 2 receives the LACPD frame received by the first port 21-n via the transfer unit 23. Based on the state information set in the LACPD frame, the control unit 24 keeps the first port 21-n in the DISTRIBUTING state. 【0045】Figure 5 is a sequence diagram showing another example of operation of communication system 1. The opposing device 2 and each communication PKG 31-n of communication device 3 perform the operations shown in Figure 5. Figure 5 is an example using ETH-CC (Ethernet® Continuity Check function) of ITU-T (International Telecommunication Union Telecommunication Standardization Sector) Y. 1731. The opposing device 2 and communication PKG 31-n send and receive CCM (Continuity Check Message) frames to inform the opposing device 2 of the status of communication PKG 31-n. The CCM frame is a signal frame used in the ETH-CC function. A CCM frame containing ETH-RDI (Ethernet® Remote Defect Indication function) information with an RDI (Remote Defect Indication) bit of 1 is referred to as CCM frame (RDI bit 1), and a CCM frame containing ETH-RDI information with an RDI bit of 0 is referred to as CCM frame (RDI bit 0). 【0046】 Communication PKG 31-n is in operation (step S201). Control PKG 39 of communication device 3 determines to perform cold standby for communication PKG 31-n. Notification unit 32-n of communication PKG 31-n transmits a CCM frame (RDIbit1) with ETH-RDI information where the RDI bit is 1 via forwarding unit 35-n from upper-level connection port 33-n to the opposing device 2 before communication PKG 31-n enters cold standby (step S202). Control unit 24 of the opposing device 2 receives the CCM frame (RDIbit1) received by the first port 21-n via forwarding unit 23. When forwarding unit 23 receives the CCM frame with ETH-RDI information where the RDI bit is 1, it stops transmitting frames to communication PKG 31-n using the first port 21-n (step S203). 【0047】After transmitting the CCM frame (RDI bit 1) in step S202, the control PKG 39 of the communication device 3 sets the communication PKG 31-n to the cold standby state (step S204). The power supply 37-n of the communication PKG 31-n stops supplying power to each part. 【0048】 After step S204, the control PKG 39 of the communication device 3 determines to release the cold standby of the communication PKG 31-n and instructs the communication PKG 31-n to transition to the operating state. The communication PKG 31-n starts supplying power from the power supply 37-n to the transfer unit 35-n, the CPU 36-n, the upper connection port 33-n, and the lower connection port 34-n, and these parts are activated by the supplied power (step S205). During the activation of each part, the notification unit 32-n continues to transmit the CCM frame (RDI bit 1) from the upper connection port 33-n to the opposing device 2 via the transfer unit 35-n, for example, at a certain time interval (steps S206, step S207). The control unit 24 of the opposing device 2 receives the CCM frame (RDI bit 1) received by the first port 21-n via the transfer unit 23. The transfer unit 23 continues to stop frame transmission to the communication PKG 31-n while receiving the CCM frame (RDI bit 1). 【0049】 When the communication PKG 31-n of the communication device 3 starts up normally, it transitions to the operating state (step S208). The notification unit 32-n transmits a CCM frame (RDI bit 0) with ETH-RDI information in which the RDI bit is 0 from the upper connection port 33-n to the opposing device 2 via the transfer unit 35-n (step S209). The control unit 24 of the opposing device 2 receives the CCM frame (RDI bit 0) received by the first port 21-n via the transfer unit 23. When the control unit 24 receives a CCM frame with ETH-RDI information in which the RDI bit is 0, it determines that the state with the communication PKG 31-n has recovered RDI. The control unit 24 starts transmitting the CCM frame to the communication PKG 31-n via the first port 21-n (step S210). 【0050】Furthermore, the communication PKG31-n of communication device 3 may stop transmitting CCM frames periodically during cold standby. After 3.5 cycles, the opposing device 2 detects an LOC (Loss of Continuity) and stops transmitting frames to the communication PKG31-n. When cold standby is released, the communication PKG31-n of communication device 3 resumes transmitting CCM frames periodically after normal startup. After 3.5 cycles, the opposing device 2 recovers the LOC and starts transmitting frames to the communication PKG31-n. 【0051】 Figure 6 is a sequence diagram showing another example of operation of communication system 1. The opposing device 2 and each communication PKG 31-n of communication device 3 perform the operations shown in Figure 6. Figure 6 is another example when using ITU-TY. 1731 ETH-CC. 【0052】 Communication PKG 31-n is in operation (step S301). In operation, the notification unit 32-n of communication PKG 31-n periodically transmits CCM frames to the opposing device 2. When the control unit 24 of the opposing device 2 receives the CCM frame received by the first port 21-n from the transfer unit 23, it determines that the continuity with communication PKG 31-n is normal. 【0053】 The control PKG 39 of the communication device 3 determines that it will perform cold standby for the communication PKG 31-n. When the communication PKG 31-n receives a transition instruction to cold standby from the control PKG 39, the notification unit 32-n stops transmitting CCM frames to the opposing device 2 (step S302). The control unit 24 of the opposing device 2 detects LOC 3.5 cycles after it stops receiving CCM frames from the communication PKG 31-n (step S303). The control unit 24 stops transmitting frames to the communication PKG 31-n via the first port 21-n. After transmitting the CCM frame in step S302, the communication PKG 31-n of the communication device 3 transitions to a cold standby state (step S304). The power supply 37-n of the communication PKG 31-n stops supplying power to each part. 【0054】After step S304, the control PKG 39 of the communication device 3 determines to release the cold standby state of the communication PKG 31-n and instructs the communication PKG 31-n to transition to the operational state. The communication PKG 31-n starts supplying power from the power supply 37-n to the notification unit 32-n, the upper-level connection port 33-n, the lower-level connection port 34-n, and the transfer unit 35-n within the communication PKG 31-n, and these units start up with the supplied power (step S305). Once each unit of the communication PKG 31-n has started up normally, it transitions to the operational state (step S306). The notification unit 32-n periodically transmits CCM frames again from the upper-level connection port 33-n to the opposing device 2 via the transfer unit 35-n (step S307). The control unit 24 of the opposing device 2 receives the CCM frames received by the first port 21-n via the transfer unit 23. The control unit 24 recovers the LOC 3.5 cycles after receiving the CCM frame. After recovery, the control unit 24 starts transmitting the CCM frame to communication PKG 31-n (step S308). 【0055】 Figure 7 is a sequence diagram showing another example of operation of the communication system 1. The opposing device 2 and each communication PKG 31-n of the communication device 3 perform the operations shown in Figure 7. Figure 7 is an example using PAUSE in IEEE 802.3 Annex 31B / IEEE 802.3x. 【0056】 Communication PKG 31-n is in operation (step S401). When the control PKG 39 of the communication device 3 determines that it will perform cold standby for communication PKG 31-n, it instructs communication PKG 31-n to transition to the cold standby state. The power supply 37-n of communication PKG 31-n stops supplying power to each part and enters the cold standby state (step S402). 【0057】After step S402, the control PKG 39 of the communication device 3 determines that the cold standby state of the communication PKG 31-n should be released and instructs the communication PKG 31-n to transition to the operational state. The communication PKG 31-n releases the cold standby state and begins supplying power from the power supply 37-n to the transfer unit 35-n, CPU 36-n, upper-level connection port 33-n, and lower-level connection port 34-n. Each part of the communication PKG 31-n starts up with the supplied power (step S403). 【0058】 The notification unit 32-n of the communication package 31-n transmits a PAUSE frame from the upper-level connection port 33-n to the opposing device 2 via the transfer unit 35-n immediately after the link between the upper-level connection port 33-n and the opposing device 2 is established (step S404). The control unit 24 of the opposing device 2 receives the PAUSE frame received by the first port 21-n via the transfer unit 23. When the control unit 24 receives the PAUSE frame from the communication package 31-n, it stops transmitting frames to the communication package 31-n via the first port 21-n (step S405). 【0059】 While the communication package 31-n is activated, the notification unit 32-n periodically transmits PAUSE frames from the upper-level connection port 33-n to the opposing device 2 via the transfer unit 35-n (steps S406, S407). The control unit 24 of the opposing device 2 receives the PAUSE received by the first port 21-n via the transfer unit 23. While the control unit 24 is receiving PAUSE frames from the communication package 31-n, it stops transmitting frames to the communication package 31-n. 【0060】 When the communication package 31-n starts up normally, it transitions to the operational state. The notification unit 32-n stops transmitting PAUSE frames (step S408). The control unit 24 of the opposing device 2 enables frame transmission to the communication package 31-n because it has stopped receiving PAUSE frames from the communication package 31-n. 【0061】According to the embodiment described above, the opposing device 2 and the multiple communication packages 31 of the communication device 3 are connected by link aggregation. The communication device 3 notifies the opposing device 2 of the status of the communication packages 31 connected to it. Based on this notification, the communication device 3 controls the opposing device 2 to send traffic only to the communication packages 31 that are in operation. Furthermore, by notifying the status of the communication packages 31, the communication device 3 can perform or release cold standby without frame loss. 【0062】 As described above, the communication device 3 transmits the status of its installed communication package 31 to the opposing device 2, thereby controlling the opposing device 2 to send traffic to the operational communication package 31 and not to send traffic to the communication package 31 in cold standby mode, without requiring any additional functions from the opposing device 2. Furthermore, the communication package 31 sends frames that cannot be received to the opposing device 2 before entering cold standby mode, and then sends frames that can be received to the opposing device 2 after exiting cold standby mode. Therefore, even when the communication device 3 autonomously controls the cold standby state of the communication package 31, frames transmitted from the opposing device 2 can be prevented from being lost. 【0063】 According to the embodiment described above, the communication device includes a plurality of communication packages, a control unit, and a notification unit. The control unit corresponds, for example, to the control PKG39 of the embodiment. The plurality of communication packages transmit and receive signals with the opposing device via different links that constitute link aggregation. The control unit controls the implementation and release of cold standby for each communication package. When the control unit decides to implement cold standby for a communication package, the notification unit notifies the opposing device that the communication package is in a communication-unavailable state before the communication package transitions to the cold standby state. Also, when the control unit decides to release cold standby for a communication package, the notification unit notifies the opposing device that the communication package is in a communication-available state after the communication package transitions from the cold standby state to the operational state. 【0064】The notification unit may notify the opposing device that the communication package is in a communication-unavailable state by repeatedly stopping the transmission of signals that would normally be sent to the opposing device while the communication package is in a communication-enabled state. Alternatively, the notification unit may notify the opposing device that the communication package is in a communication-unavailable state between the time the control unit decides to release the communication package from cold standby and the time the communication package completes its transition from cold standby to operational state. 【0065】 While embodiments of this invention have been described in detail above with reference to the drawings, the specific configurations are not limited to these embodiments and include designs and the like that do not depart from the spirit of this invention. 【0066】 1 Communication system 2 Opposite device 3 Communication device 21 First port 22 Second port 23 Transfer unit 24 Control unit 31 Communication package 32 Notification unit 33 Upper connection port 34 Lower connection port 35 Transfer unit 36 ​​CPU 37 Power supply

Claims

1. A communication device comprising: a plurality of communication packages that send and receive signals with a counterpart device via different links constituting link aggregation; a control unit that controls the implementation and release of cold standby for each of the communication packages; and a notification unit that, when the control unit decides to implement cold standby for the communication package, notifies the counterpart device that the communication package is in a communication-unavailable state before the communication package transitions to the cold standby state, and when the control unit decides to release cold standby for the communication package, notifies the counterpart device that the communication package is in a communication-available state after the communication package transitions from the cold standby state to the operational state.

2. The communication device according to claim 1, wherein the notification unit notifies the opposing device that the communication package is in a communication-unavailable state by repeatedly stopping the transmission of signals to be transmitted to the opposing device while the communication package is in a communication-enabled state.

3. The communication device according to claim 1, wherein the notification unit notifies the opposing device that the communication package is in a communication-unavailable state between the time the control unit decides to release the communication package from cold standby and the time the communication package finishes transitioning from the cold standby state to the operational state.

4. A communication control method comprising: a control step for controlling the implementation and release of cold standby for each of a plurality of communication packages that transmit and receive signals with a counterpart device via each of the different links constituting a link aggregation; and a notification step for notifying the counterpart device that the communication package is in a communication-unavailable state before the communication package transitions to a cold standby state when it is decided in the control step to implement cold standby for the communication package, and notifying the counterpart device that the communication package is in a communication-available state after the communication package transitions from a cold standby state to an operational state when it is decided in the control step to release cold standby for the communication package.

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