JP2009296441A - Network system, network terminal device, and lan switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce power consumption during the standby state of a network terminal device without incurring degradation in network performance nor trouble, in a network system constructed using a LAN switch having a spanning tree function. <P>SOLUTION: Network terminal devices 1, 2 are connected to each other via LAN switches 11-13 each having a spanning tree function. When shifting to a power saving mode, the first and the second network terminal devices 1, 2 notifies the LAN switch 12, 13 connected thereto of shifting. When notified, the LAN switches 12, 13 set ports connected to the network terminal device 1, 2 to edge ports and set the spanning tree functions of the ports to be invalid. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a network system in which a plurality of network terminal devices are connected by a LAN switch, and the network terminal device and the LAN switch.

  Currently, an information processing apparatus such as a personal computer (hereinafter referred to as a PC) or an image forming apparatus has a power saving mode in a standby state waiting for a processing request in addition to a normal mode for performing normal information processing. Thus, the power consumption of the information processing apparatus is reduced. As a means for realizing the power saving mode, there is a clock frequency reduction control. Information processing cannot be performed in the power saving mode, or even if it can be performed, the processing capability is reduced as compared to the normal mode. Therefore, when a processing request is generated in the power saving mode, the processing is returned to the normal mode and the request is processed.

  Since an information processing apparatus connected to a network (having a network interface) has a processing request via the network, the network interface is normally operated even in the power saving mode, and when the processing request is received via the network, the network The interface returns the other parts to the normal mode (see Patent Document 1).

  By the way, in a general network environment, a network system is constructed using a LAN switch. The LAN switch has an address table for managing network terminal devices connected to each port, and broadcast packets and destination packets not in the address table continue to travel around the network (broadcast storm, etc.) For the purpose of prevention, it has a function called Spanning Tree. According to this function, when a terminal device is newly added to the network, the LAN switch detects a change in the network configuration, performs address registration of the added terminal device, searches for a network route, and the network has a loop structure. The optimal network route is constructed so that it does not become. The LAN switch performs this operation every time the network configuration changes.

  Among the network interfaces of such network terminals, the power consumption of PHY (physical layer) devices is the largest. In particular, the power consumption when communicating at IGbps is very large. Therefore, in the power saving mode, it is conceivable to reduce power consumption by reducing the transfer rate of the network interface to 100 Mbps or the like.

However, changing the transfer rate of the network interface in the power saving mode has the following problems. When the network interface transfer rate is changed, the link will always be down / up. In a network environment constructed with a LAN switch equipped with the spanning tree function, the link down Each time / up occurs, the LAN switch determines that the network configuration has changed, and changes the held address table or reconstructs the network route. If the operation of the LAN switch is frequently performed in accordance with the transition to the power saving mode and the return to the normal mode in the network terminal device, the network is caused by frequent retry without data transfer and increased traffic. Problems such as performance degradation and data not reaching.
JP 2003-76451 A

  The present invention has been made to solve such a problem, and the object of the present invention is to prevent a decrease in network performance or a malfunction in a network system constructed using a LAN switch equipped with a spanning tree function. In addition, it is to reduce the power consumption of the network terminal device during standby.

  The network system of the present invention has a normal mode, a power saving mode in which power consumption and communication speed are lower than those in the normal mode, a plurality of network terminal devices whose link state changes when the communication speed changes, and their networks A network system comprising a plurality of LAN switches having a spanning tree function to which a terminal device is connected, wherein the network terminal device notifies the LAN switch connected to the network device to transition to a power saving mode When receiving the notification, the LAN switch has a means for invalidating a spanning tree function of a port to which the network terminal device that has made the notification is connected.

[Action]
According to the present invention, in a network system constructed using a LAN switch equipped with a spanning tree function, the network terminal device notifies the LAN switch connected to the network terminal device that the network terminal device shifts to the power saving mode. When receiving the notification, the LAN switch disables the spanning tree function of the port to which the network terminal device is connected. As a result, the network terminal device can improve the processing efficiency by performing high-speed communication in the normal mode (during operation), and increase the productivity, while the communication speed is reduced in the power saving mode (during standby). Power consumption can be reduced by responding to the minimum required network response.

  According to the present invention, in a network system constructed using a LAN switch equipped with a spanning tree function, it is possible to reduce the power consumption of the network terminal device without causing a drop in network performance or a malfunction.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a network system according to an embodiment of the present invention. This network system includes first and second network terminal apparatuses 1 and 2 and first to third LAN switches 11 to 13. Here, the first network terminal device 1 is a printer, and the second network terminal device 1 is a PC.

  The first and second network terminal apparatuses 1 and 2 are connected (connected) to the second and third LAN switches 12 and 13 by LAN cables 25 and 26, respectively. The first and second LAN switches 11 and 12 are connected by a LAN cable 22, the second and third LAN switches 12 and 13 are connected by a LAN cable 24, and the third and first LAN switches 13, 11 are connected by a LAN cable 23. The first LAN switch 11 is connected to the backbone network 21. That is, the first to third LAN switches 11 to 13 are connected in a loop by the LAN cables 22 to 24.

  Each LAN switch is configured to transmit a packet, such as a broadcast packet, that is simultaneously transmitted to network terminal devices to all ports. In the loop structure shown in the figure, the packet continues around until some connection is released. As a result, the network traffic increases, causing problems such as a decrease in the throughput of the entire network and the inability to transmit data to the target location.

  Therefore, this problem is solved by the spanning tree function. That is, as shown in FIG. 2, the connection (path) between the second and third LAN switches 12 and 13 is blocked so that the network does not have a loop structure. In the case of this structure, for example, when data is to be transferred from the second terminal device 2 to the first terminal device 1, the third LAN switch 13 to which the second terminal device 2 is connected receives the received data. Send to the first LAN switch 11. Since the first LAN switch 11 knows that the first terminal device 1 is connected to the second LAN switch 12, it transfers data to the second LAN switch 12, and the second LAN switch 11 Data is transferred from 12 to the first terminal device 1.

  When establishing this route, each LAN switch constantly monitors the network configuration, and if there is a change in the configuration, it updates the address table held by the LAN switch, searches the network route, and reestablishes the route. .

  FIG. 3 shows an example of an address table held by each LAN switch. The address of the other party connected to each port of the LAN switch is held corresponding to each port. The LAN switch can determine a new connection partner by updating this address table when the network path changes or the connection state of the port changes. In many cases, this is managed mainly by a MAC (Media Access Control) address possessed by each network terminal device.

  4 and 5 are diagrams for explaining an example of a network path establishment method. Here, FIG. 4 is a state before establishment, and four LAN switches 101 to 104 are connected in a loop by four LAN cables 111 to 114. FIG. 5 is after establishment, and the connection (path) between the LAN switches 102 and 103 is blocked.

  The major factors when determining the route are the bridge ID and the path cost. 4 and 5, the numbers in the rectangles arranged above or below each LAN switch are the bridge IDs, and the numbers in circles arranged on each LAN cable are the path costs.

  The bridge ID determines a value for each LAN switch, and the LAN switch having the smallest value becomes a root bridge (mainly manages the network path). This is set by the user. The path cost is a value determined for each line speed, and is a material for determining “closeness” for reaching the root bridge. This is determined by the line speed, for example, 100 for a line speed of 10 Mbps, 19 for a line speed of 100 Mbps, and 4 for a line speed of 1 Gbps.

  In the example of FIG. 4, since the bridge IDs of the LAN switches 101, 102, 103, and 104 are set to 10, 30, 20, and 20, respectively, the LAN switch 101 becomes a root bridge. The line speed is 4 (1 Gbps) between the LAN switches 101 and 104, 19 (100 Mbps) between the LAN switches 101 and 102, 100 (10 Mbps) between the LAN switches 102 and 103, and 19 (100 Mbps) between the LAN switches 103 and 104. ).

  When establishing a network path so as not to have a loop structure, each LAN switch determines a root bridge by looking at a bridge ID possessed by each LAN switch. Here, the LAN switch 101 serves as a root bridge. Thereafter, a port (root port) that can reach the root bridge with the shortest path is selected for each LAN switch. In the case of the LAN switches 102 and 104, the port to which the LAN switch 101 as the root bridge is connected is selected. In the case of the LAN switch 103, the path cost of the route via the LAN switch 102 and the route cost via the LAN switch 104 are compared, and the port to which the smaller LAN switch 104 is connected is set as the root port. That is, between the LAN switches 101 and 103, “100 + 19 = 119” if the LAN switch 102 is passed, and “19 + 4 = 23” if the LAN switch 104 is passed, and the latter is determined to be the shortest. As a result, the LAN switches 102 and 103 are disconnected as shown in FIG.

  Each LAN switch exchanges a BPDU (Bridge Protocol Data Unit) packet as shown in FIG. 6 so as to know the bridge ID and the path cost. The meaning of each data in the BPDU packet and the details of the procedure for establishing the network path are already known (IEEE 802.1d), and thus detailed description thereof is omitted.

  7 to 10 are flowcharts showing the operation of the network system of this embodiment. Here, FIG. 7 shows the operation when the network terminal device shifts from the normal mode to the power saving mode, and FIG. 8 shows the operation when the LAN switch is notified of the shift from the network terminal device to the power saving mode. is there. FIG. 9 shows the operation when the network terminal device shifts (returns) from the power saving mode to the normal mode, and FIG. 10 is notified that the LAN switch shifts (returns) from the network terminal device to the normal power mode. It is the operation when. That is, FIG. 9 is an operation following FIG. 7, and FIG. 10 is an operation following FIG. The operations shown in these figures are performed by the respective CPUs executing the programs written in the respective ROMs in the network terminal device and the LAN switch.

  As shown in FIG. 7, when there is no operation request for a certain period of time from the normal operation state (step S1 → S2: YES) and the network terminal device shifts to the power saving mode (step S3: YES), the network terminal device A packet notifying that is sent out (step S4). Thereafter, the network speed (communication speed) is set low (step S5), and the mode is shifted to the power saving mode (step S6).

  As shown in FIG. 8, when the LAN switch receives a notification of transition to the power saving mode from the network terminal device during monitoring of each port (step S11 → S12: YES), the LAN switch is not connected to the port. A meaning edge port is set (step S13). Then, it is set to be invalid so that the spanning tree function does not work for that port (step S14). Thereafter, the port is monitored (step S15).

  As shown in FIG. 9, the network terminal device communicates at a reduced network speed (communication speed) in the power saving mode, and when there is an operation request (step S21: YES), the network terminal device changes from the power saving mode to the normal mode. The return is notified to the LAN switch side (step S22). Thereafter, the network speed is returned to the high transfer rate in the normal operation state (step S23), the normal operation state (normal mode) is restored (step S24), and data is transmitted and received.

  As shown in FIG. 10, when the terminal device receives the power saving mode return notification from the edge port monitoring (step S31 → S32: YES), the auto negotiation function is first executed for the port (step S33). This operation is an operation for attempting to link in accordance with the communication speed of the other party. As a result, when the link can be made at the speed requested by the network terminal device side (step S34), the edge port setting of the port is canceled (step S35). Thereafter, the spanning tree function is set to be valid (step S36).

  The operations in FIGS. 7 to 10 are basically as follows. The network terminal apparatus throws a packet to the LAN switch of the connection partner. The contents include contents such as whether or not to enter the power saving mode in addition to the address and other functions. If the LAN switch receives the packet and finds that the network terminal device is going into the power saving mode, change the setting of the port to which the network terminal device is connected so that the spanning tree function does not work only for that port. To do. Thereby, the network terminal device side can change the network speed from a high speed to a low speed, and the power consumption can be kept low.

  In addition to the procedure described with reference to FIGS. 7 to 17, the LAN switch performs auto-negotiation when detecting an up / down of the link that occurs when the network terminal device enters the power saving mode, and A procedure may be used in which the spanning tree function is not executed if there is no difference in the addresses when the MAC address of the side is acquired and compared with the address table held by itself.

Thus, the network system of this embodiment has the following effects (1) to (6).
(1) Before the network terminal device shifts to the power saving mode, the LAN switch that is the connection partner is notified of the shift to the power saving mode, and the LAN switch notifies the shift to the power saving mode. The port to which the network terminal device is connected is set to a terminal port (edge port) meaning that a LAN switch different from the above-mentioned LAN switch is not connected, and the terminal device is in the power saving mode. During this period, the spanning tree function of the LAN switch is disabled so that it does not work, so it operates at the maximum communication speed in the normal mode and reduces the communication speed in the power saving mode to reduce power consumption. it can.

  (2) When the network terminal device returns to the normal operation state from the power saving mode, the network terminal device is in the power saving mode state indefinitely by notifying the LAN switch that is the connection partner to that effect. Can be prevented from being erroneously determined.

  (3) The network terminal device performs a notification to the effect of returning from the power saving mode to the normal operation state when the network terminal device is in the power saving mode state before returning to the normal operation state. It is possible to prevent the edge port from being erroneously set due to the change of the link state when returning to the state.

  (4) When the LAN switch receives a notification from the power saving mode to return to the normal operation state from the network terminal device, the LAN switch sets the edge port setting set for the port to which the network terminal device is connected. By canceling and enabling the spanning tree function, it is possible to cope with a change in the network path or a change in the network configuration.

  (5) When the connected network terminal device is in the power saving mode and has not yet released the power saving mode, the LAN switch monitors the link status of the port and detects a change in the link status. In this case, the edge port setting set for the port is canceled and the spanning tree function is enabled, so that it is possible to cope with a case where the cable is inadvertently disconnected or a change in the network configuration.

  (6) When the network terminal device enters the energy saving mode at a reduced communication speed, the LAN switch detects the link up / down of the port to which the network terminal device is connected, and before executing the spanning tree function, The address of the network terminal device connected to the port is searched and compared with the address held in its own address table. If it is the same, the address table is not rewritten, the address is held, and the spanning tree By not executing the function, it is possible to prevent the network performance from being deteriorated due to unnecessary reconfiguration of the network route or change of the address table.

It is a figure which shows the structure of the network system of embodiment of this invention. FIG. 2 is a diagram illustrating a state in which the network does not have a loop structure in the network system of FIG. 1. FIG. 2 is a diagram illustrating an example of an address table held by each LAN switch in FIG. 1. It is a figure which shows the connection state before establishment of a network path | route. It is a figure which shows the connection state after establishment of a network path | route. It is a figure which shows the format of the BPDU packet transmitted / received in the procedure of establishment of a network path | route. It is a flowchart which shows operation | movement when a network terminal device transfers to normal power saving mode from normal mode. It is a flowchart which shows operation | movement of a LAN switch when notified to transfer to a power saving mode from a network terminal device. It is a flowchart which shows operation | movement when a network terminal device transfers to a normal mode from a power saving mode. It is a flowchart which shows operation | movement of a LAN switch when notified to transfer to a normal power mode from a network terminal device.

Explanation of symbols

  1, 2... Network terminal device, 11 to 13, 101 to 103... LAN switch.

Claims (6)

A normal mode and a power saving mode with lower power consumption and communication speed than the normal mode, and a plurality of network terminal devices whose link state changes when the communication speed changes, and those network terminal devices are connected, A network system comprising a plurality of LAN switches having a spanning tree function,
The network terminal device includes a means for notifying a LAN switch connected to the network terminal device that the network terminal device shifts to a power saving mode, and when the LAN switch receives the notification, the network terminal device that has made the notification A network system comprising means for invalidating a spanning tree function of a connected port. A normal mode and a power saving mode with lower power consumption and communication speed than the normal mode, and a plurality of network terminal devices whose link state changes when the communication speed changes, and those network terminal devices are connected, A network terminal device used in a network system including a plurality of LAN switches having a spanning tree function,
A network terminal device comprising means for notifying a LAN switch connected to itself of shifting to a power saving mode. In the network terminal device according to claim 2,
A network terminal device comprising means for notifying a LAN switch connected to itself of returning to a normal mode. A normal mode and a power saving mode with lower power consumption and communication speed than the normal mode, and a plurality of network terminal devices whose link state changes when the communication speed changes, and those network terminal devices are connected, A LAN switch used in a network system including a plurality of LAN switches having a spanning tree function,
When receiving notification from the network terminal device connected to itself that the network terminal device shifts to the power saving mode, it has means for invalidating the spanning tree function of the port to which the network terminal device is connected. LAN switch. The LAN switch according to claim 4,
A LAN switch comprising means for enabling the spanning tree function of a port when the link state of the port for which the spanning tree function is disabled changes. A normal mode and a power saving mode with lower power consumption and communication speed than the normal mode, and a plurality of network terminal devices whose link state changes when the communication speed changes, and those network terminal devices are connected, A LAN switch used in a network system including a plurality of LAN switches having a spanning tree function,
Means for acquiring the address of the network terminal connected to the port when a change in the link status is detected, means for comparing the acquired address with the address held in its own address table, and the result of the comparison A LAN switch comprising means for holding the address without rewriting the address table if they are the same, and means for invalidating the spanning tree function.

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