JP4089698B2 - Network system, tree reconfiguration processing method, node, tree reconfiguration processing program - Google Patents

Description

  The present invention relates to a network system, and more particularly to a network system, a spanning tree reconfiguration processing method, and a spanning tree reconfiguration processing program that do not stop a network when reconfiguring a spanning tree.

  Conventionally, in Ethernet (R), when an output port has not been determined, a method is used in which an output port is determined by broadcasting a frame and learning its source address and reception port. Therefore, when the network physical shape includes a loop shape, the broadcasted frame may continue to circulate.

  In order to prevent such frame circulation, a control method called Spanning Tree Protocol (hereinafter referred to as STP) is defined in IEEE (IEEE 802.1D or its high-speed version IEEE802.D). 1w) This makes it possible to configure a network that logically excludes loops.

  However, in STP, when a node or link is added or deleted, all or part of the spanning tree is stopped and the tree is rebuilt. In some cases, disposal occurred.

  In order to avoid this, for example, the proposal of next generation Ethernet (R) architecture GOE (Global Optical Ethernet (R))-(3) Service non-stop spanning tree reconstruction and load distribution-(2000 IEICE) (Communication Society Conference Proceedings: Issued August 20, 2002) (Non-Patent Document 1) proposes the following method.

  In a network using STP, two spanning trees are prepared, and when adding or deleting nodes or links, the other spanning tree is used for frame transfer while keeping the spanning tree before the network configuration is changed. To create a new spanning tree after changing the network configuration. Then, after the new spanning tree is stabilized, the spanning tree used for frame transfer is switched to the new spanning tree.

  In this method, the spanning tree that is unstable when the network configuration is changed by adding or deleting nodes or links is not used for frame forwarding, and the network configuration is always used while using a stable spanning tree. Changes can be made.

Proposal of Next Generation Ethernet (R) Architecture GOE (Global Optical Ethernet (R))-(3) Service Non-stop Spanning Tree Reconstruction and Load Balancing- (2000 IEICE Communication Society Conference Proceedings: 2002) (Issued on August 20)

  The conventional techniques described above have the following problems.

  First, in the method described in Non-Patent Document 1 described above, the number of spanning trees that can be used in the network is limited.

  That is, in the method of Non-Patent Document 1, two spanning trees are prepared, and one is used for frame transfer, and the other is used for constructing a new spanning tree accompanying a network configuration change.

  Therefore, when using N spanning frames for frame transfer, it is necessary to prepare 2N spanning trees. When a plurality of spanning trees are used, the tree is generally identified by a VLAN tag, and the number of spanning trees that can be used in the network is generally 4096 defined as the number of VLAN-IDs. The number is 4095, minus the number of reservation IDs (VLAN-ID = 4095 is reserved and cannot be used).

  In the method according to Non-Patent Document 1, a spanning tree having twice the number of planes used for frame transfer is required. Therefore, the number of spanning trees that can actually be used for frame transfer is 2047 at the maximum. It will be limited to half. For this reason, there is a problem that the scalability of the network is limited.

  Secondly, with the method according to Non-Patent Document 1, the processing load on the spanning tree increases.

  That is, in the method according to Non-Patent Document 1, as described above, when an N-plane spanning tree is used for frame transfer, a spanning tree is operated in order to operate a spanning tree having twice the number of planes (2N). The number of control frames for control must be processed twice, increasing the processing load.

  An object of the present invention is to enable reconfiguration of a spanning tree without stopping the network when the network configuration is changed, and to solve the conventional problem in which the number of spanning trees that can be used in the network is limited to one half. The object is to propose a network system, a tree reconfiguration processing method, a node, and a tree reconfiguration processing program that can be avoided and maintain extensibility.

  Another object of the present invention is to reduce the number of control frames for controlling the spanning tree to reduce the processing load required for processing the control frames, a tree reconfiguration processing method, The object is to provide a node and tree reconstruction program.

  In order to achieve the above object, in the network system of the present invention, in a network system using a plurality of trees as a path for transferring a frame on a network in which a plurality of nodes are connected, nodes are added to or deleted from the network. At least one spare tree used when reconstructing the tree is provided, and the spare tree is shared in the tree reconstruction of the plurality of trees.

  According to the present invention, when the management server receives an addition or deletion request from a node to be added or deleted, confirms the usage status of the spare tree, and when the spare tree is usable, A permission is notified to the node to be added or deleted, and a tree reconfiguration is requested to the root node of the requested tree.

  Alternatively, the root node of the tree receives an addition or deletion request from the node to be added or deleted, inquires the usage status of the spare tree to the management server, and the management server If a tree is available, a tree reconfiguration is requested to the root node of the tree.

  Further, the node to be added or deleted notifies the use reservation of the spare tree in the network, and if the spare tree is not in use, notifies the use of the spare tree to the network. Thus, a request for addition or deletion is made to the root node of the tree, and the root node of the tree receives the request for addition or deletion, and executes a tree reconfiguration process.

(Function)
In the present invention, when a tree is reconfigured by adding or deleting a node to a plurality of spanning trees in which frame forwarding is performed, the management server is added from the node that is added to or deleted from the spanning tree. When an add or delete request is received, the usage status of the spare tree is confirmed. When the spare tree is usable, permission is notified to the node to be added or deleted, and the requested spanning tree Request tree reconstruction for root node. Upon receiving the request, the root node of the spanning tree uses the spare tree to execute the tree reconfiguration process without stopping the network.

  Alternatively, when the root node of the spanning tree receives an addition or deletion request from a node that is added to or deleted from the spanning tree, the management server inquires about the usage status of the spare tree. The management server that has received the usage status inquiry requests tree reconfiguration to the root node of the spanning tree when the spare tree is usable.

  In addition, when a dedicated management server for managing the state of the spanning tree is not provided, a node that is added to or deleted from the spanning tree notifies the use reservation of the spare tree in the network and If the tree is not in use, a request for addition or deletion is made to the root node of the spanning tree by notifying the use of the spare tree in the network.

  As a result, the spanning tree can be reconfigured without stopping the network when the network configuration is changed.

  According to the network system of the present invention, the following excellent effects are achieved.

  At least one spare tree for use in tree reconfiguration by adding or deleting nodes to a plurality of spanning trees is provided, and this spare tree is configured to be shared in the tree reconfiguration of a plurality of spanning trees. Therefore, it is possible to reconfigure the spanning tree without stopping the network when the network configuration is changed, and to avoid the conventional problem that the number of spanning trees that can be used in the network is limited to one-half, and to expand Sex can be maintained.

  In addition, the number of control frames for controlling the spanning tree can be reduced, and the processing load required for processing the control frames can be reduced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  In the following description, a description will be given using a tag as an identifier for identifying a plurality of spanning trees and a plurality of nodes. This tag, in addition to the VLAN tag, is disclosed in Japanese Patent Application Laid-Open No. 2004-140776 by the present applicant. It means a single or a combination of one or more of the expansion tag and other tags or identification means disclosed in No. 1.

  Here, among the tags used in the present invention, the format of a frame with an extension tag disclosed in the above Japanese Patent Application Laid-Open No. 2004-140776 will be described.

  FIG. 1 shows an Ethernet (R) frame format with a VLAN tag defined by IEEE 802.1Q. An Ethernet (R) frame 3200 with a VLAN tag includes a transmission destination MAC address 3201, a transmission source MAC address 3202, a VLAN tag 3203, Ethernet (R) attribute information 3204, a payload 3205, and an FCS (Frame Check Sequence) 3206. It consists of.

  On the other hand, FIG. 2 shows the format of an Ethernet (R) frame with an extension tag according to the present invention. The Ethernet frame with extension tag 3300 includes a transmission destination MAC address 3201, a transmission source MAC address 3202, an expansion tag storage area 3301, Ethernet (R) attribute information 3204, a payload 3205, and an FCS 3206. The VLAN tag 3203 of the existing Ethernet (R) frame with VLAN tag 3200 is replaced with the expansion tag storage area 3301.

  Further, as shown in FIG. 3, there is an Ethernet frame 3400 with an extension tag having another configuration, which includes a destination MAC address 3201, a source MAC address 3202, an extension tag storage area 3301, and a VLAN tag 3203. , Ethernet (R) attribute information 3204, payload 3205, and FCS 3206, and the extension tag storage area 3301 is inserted after the source MAC address 3202.

  One or a plurality of expansion tags can be stored in the expansion tag storage area 3301. The size of one expansion tag is 4 bytes, which is the same size as the VLAN tag 3203. The uppermost expansion tag of the Ethernet (R) frames 3300 and 3400 with the expansion tag and the VLAN tag of the Ethernet (R) frame 3200 with the VLAN tag are stored in the same position and with the same size. Are distinguished by changing the value stored in the upper 2 bytes of the data (details will be described later).

  As a result, Ethernet frames with extended tags (R) 3300 and 3400 are compatible with Ethernet frames with VLAN tags (R) 3200, and both frames can be processed by both existing nodes and nodes that support extended tags. It is.

  FIG. 4 shows the expansion tag storage area 3301. In the storage example shown in FIG. 4, eight expansion tags 3500-3507 are stored.

  The forwarding tag 3500 stores an identifier of a destination node (node to which the destination client is connected) and a label up to the destination (for example, an MPLS label). In addition to the forwarding tag 3500 that stores the identifier of the destination node, the identifier of the transmission source node may be stored. Each node determines a frame transfer destination with reference to the forwarding tag. The forwarding tag 3500 is always stored in Ethernet frames (R) frames 3300 and 3400 with extension tags.

  As types of expansion tags, a customer separation tag 3501, a protection tag 3502, an OAM & P tag 3503, a quality information tag 3504, a frame control tag 3505, a security tag 3506, and a user expansion tag 3507 are stored.

  The customer separation tag 3501 stores an identifier for separating information for each customer accommodated in each node. As customers, the customers belonging to the same VLAN are the same customers, the customers accommodated in specific ports of two or more nodes are the same customers, or two connected to the nodes in the network. There are cases where the above hosts are the same customer. A separation identifier is assigned to these customers, and this separation identifier is stored in a customer separation tag 3501 in a frame from each customer. By identifying a customer with the customer separation tag 3501, it is possible to provide an additional service (for example, priority control for a specific customer) in units of customers. Further, a plurality of customer separation tags 3501 can be used in a stacked manner. In this case, the number of separable customers can be greatly increased. When the customer separation tag 3501 is stacked, a special customer separation tag indicating that the customer separation tag 3501 at the last stage stacked is the last stage is used.

  The protection tag 3502 stores fault information when a fault occurs and detour path information for fault recovery. The OAM & P tag 3503 stores operation / management information.

  The quality information tag 3504 stores quality information such as delay, jitter, packet loss rate, time stamp indicating the inflow time of the frame into the network, and band control information. When the time stamp value is stored in the quality information tag 3504, the node that has received the frame can calculate the delay in the network (stay time in the network) of the frame from the current time and the time stamp value. When a guaranteed value for the delay in the network is determined, priority processing can be performed so that the guaranteed value can be realized. In addition, when the quality information tag 3504 stores bandwidth control information such as a requested bandwidth, accumulated data amount, traffic class, etc., the request is made in consideration of the accumulated data amount of the flow, the traffic class and the traffic status of other flows. Band control for securing the band can be performed.

  The frame control tag 3505 stores information such as a hop counter (TTL: Time To Live) that limits the lifetime of the frame in the network and a CRC for error detection. When the TTL is stored, the TTL value is subtracted for each passing node, and this frame is discarded when TTL = 0. As a result, it is possible to prevent the frame from continuing to circulate even when the loop path is reached. When the CRC is stored, the CRC calculation result of the extension tag storage area 3301 in the entry side node is stored, and the CRC calculation is performed again in the exit side node and compared with the stored value. An error in the storage area 3301 can be detected.

  The security tag 3506 stores information for ensuring the reliability of the frame and the confidentiality at the time of network construction or network configuration change. Examples of usage of the security tag 3506 include the following examples. A security identifier for each customer is set in advance for the customers communicating in the network, and the identifier is held in each node to which the customer connects. Each customer always stores the set security identifier in the security tag 3506 at the time of frame transfer, so that transmission / reception of a frame from a malicious customer who has altered the information in the customer separation tag 3501 can be prevented. In addition, when a network is constructed or a network configuration is changed, a common security identifier is set by negotiating between nodes. By always storing the set security identifier in the security tag 3506 during frame transfer between the nodes, it is possible to prevent a malicious node from being connected to the network.

  The user expansion tag 3507 stores arbitrary information defined by the user. When the user uniquely defines the tag format and stored information and defines the processing contents, the user can expand the functions unique to the user and increase the flexibility of the network.

  Expansion tags 3501 to 3507 other than the forwarding tag 3500 are stored as necessary. The forwarding tag 3500 is stored at the top of the expansion tag storage area 3301, and the other expansion tags 3501 to 3507 are stored behind it. As long as it is behind the forwarding tag 3500, it may be a predetermined fixed position or an arbitrary position.

  Hereinafter, of the two spanning trees, a spanning tree used for transferring a data frame newly inserted into the network is represented as a working tree, and a tree that is not a working tree is represented as a spare tree.

  BPDU (Bridge Protocol Data Unit) refers to control data described in IEEE 802.1D (Prior Art 1) and IEEE 802.1w (Prior Art 2) exchanged for spanning tree generation, and current and spare of the present invention. This refers to a control frame including identification information for use.

  FIG. 5 is a format diagram showing the structure of Configuration BPDU 2205 described in IEEE 802.1D (Prior Art 1) and IEEE 802.1w (Prior Art 2).

  The MAC DA 2201 is an area for storing a destination MAC address.

  The MAC SA 2202 is an area for storing a source MAC address.

  A tag area 2203 is an area into which a tag as an identifier for identifying a plurality of spanning trees is inserted. Although not described in the prior art, the tag is not only a VLAN tag but also an expansion tag disclosed in Japanese Patent Application Laid-Open No. 2004-140776 by the applicant of the present patent and any other tag or identification means. One or more combined tags may be used.

  Type 2204 is an area for storing a frame type identifier.

  The BPDU area 2205 is an area for storing information corresponding to Configuration BPDU parameters described in IEEE 802.1D (Prior Art 1) and IEEE 802.1w (Prior Art 2).

  The FCS 2206 is an area for storing a frame check sequence.

  The Protocol Identifier 22051 is an area for storing information equal to the Protocol Identifier described in IEEE 802.1D (Prior Art 1) or IEEE 802.1w (Prior Art 2).

  The Protocol Version Identifier 22052 is an area for storing information equal to the Protocol Version Identifier described in IEEE 802.1D (Prior Art 1) or IEEE 802.1w (Prior Art 2).

  The BPDU Type 22053 is an area for storing information equal to the BPDU Type described in IEEE 802.1D (Prior Art 1) or IEEE 802.1w (Prior Art 2).

  Flags 22054 is an area for storing information equal to Flags described in IEEE 802.1D (conventional technology 1) or IEEE 802.1w (conventional technology 2).

  The Root Identifier 22055 is an area for storing information equal to the Root Identifier described in IEEE 802.1D (Prior Art 1) or IEEE 802.1w (Prior Art 2).

  The Root Path Cost 22056 is an area for storing information equal to the Root Path Cost described in IEEE 802.1D (conventional technology 1) or IEEE 802.1w (conventional technology 2).

  The Bridge Identifier 22057 is an area for storing information equal to the Bridge Identifier described in IEEE 802.1D (Prior Art 1) or IEEE 802.1w (Prior Art 2).

  The Port Identifier 22058 is an area for storing information equal to the Port Identifier described in IEEE 802.1D (conventional technology 1) or IEEE 802.1w (conventional technology 2).

  Message Age 22059 is an area for storing information equal to Message Age described in IEEE 802.1D (conventional technology 1) or IEEE 802.1w (conventional technology 2).

  The MAX Age 2205A is an area for storing information equal to the MAX Age described in IEEE 802.1D (conventional technology 1) or IEEE 802.1w (conventional technology 2).

  The Hello Time 2205B is an area for storing information equal to the Hello Time described in IEEE 802.1D (Prior Art 1) or IEEE 802.1w (Prior Art 2).

  The Forward Delay 2205C is an area for storing information equivalent to the Forward Delay described in IEEE 802.1D (Prior Art 1) or IEEE 802.1w (Prior Art 2).

  FIG. 6 is a format diagram showing the structure of Topology Change Notification BPDU described in IEEE 802.1D (Prior Art 1) and IEEE 802.1w (Prior Art 2).

  The MAC DA 2201 is an area for storing a destination MAC address.

  The MAC SA 2202 is an area for storing a source MAC address.

  The tag area 2203 is an area in which a tag as an identifier for identifying a plurality of spanning trees is inserted, although not described in the prior art. In addition to the VLAN tag, the tag may be a combination tag of any one or more of an expansion tag and other tags or identification means disclosed in Japanese Patent Application Laid-Open No. 2004-140776.

  Type 2204 is an area for storing a frame type identifier.

  The BPDU area 2205 is an area for storing information corresponding to Topology Change Notification BPDU parameters described in IEEE 802.1D (conventional technique 1) and IEEE 802.1w (conventional technique 2).

  The FCS 2206 is an area for storing a frame check sequence.

  Next, another frame format of the extension tag frames 3300 and 3400 will be described with reference to FIG.

  The upper part of FIG. 7 shows a detailed frame format of the VLAN tag 3203. A value “0x8100” is set in a TPID (Tag Protocol Identifier) 2800. Note that the value “0x9100” may be used although it is not standard. The TCI 2801 includes a Priority field 2802, a CFI field 2803, and a VLAN-ID field 2804.

  The priority field 2802 stores the priority of the frame, and the priority value is defined in IEEE 802.1p. The CFI field stores a value indicating the presence / absence of special routing information or the type of MAC address format, and the VLAN-ID field 2804 stores a VLAN-ID.

  On the other hand, in the extended tag frame format shown in the lower part of FIG. 7, the CFI field 2803 in the TPID 2800 and TCI 2801 is the same as the VLAN tag 3203, and the Priority field 2802 is set in the Priority / tag Type field 5003. The field 2804 is changed to an expansion tag information field 5004. The size of the corresponding field is the same.

  In this extended tag frame format, the types of extended tags 3500-3508 are stored in the Priority / Tag Type field 5003. Note that a part of the Priority value in the Priority field 2802 (IEEE 802.1p) of the existing VLAN tag 3203 is used as the type of the extension tags 3500-3508 so that the existing IEEE 802.1p can be supported even when the extension tags 3500-3508 are used. Use.

  Specifically, 110, 100, 001, 000 are used for expansion tags 3500-3508, 111 (for reservation), 101 (for conversational multimedia), 011 (for critical application), 010 (standard stream) ) Is compatible with the conventional IEEE802.1p.

  Therefore, the number of expansion tags 3500-3508 that can be used is limited to four. For example, the forwarding tag 3500, the broadcast forwarding tag 3508, the customer separation tag 3501, the OAM & P tag 3503 are used, and the correspondence with the value of the Priority / Tag Type field is used. 001 = forwarding tag 3500, 000 = broadcast forwarding tag 3508, 110 = customer separation tag 3501, 100 = OAM & P tag 3503. As a result, the four types of extension tags can be identified, and four priorities in IEEE 802.1p can be supported. Each node on each network stores the correspondence between the value of the Priority / Tag Type field and the extension tag. The selection of the extension tag to be used and the setting of the value of the Priority / tag Type field corresponding to the selection are not limited to this example.

  In the extended tag frame format shown in FIG. 7, information such as address information corresponding to the tag type of the extended tags 3500 to 3508 is stored in the extended tag information field 5004. For example, in the case of the forwarding tag 3500, address information of the destination node is stored, in the case of the broadcast forwarding tag 3508, address information of the transmission source node is stored, and in the case of the customer separation tag 3501, customer identification information is stored.

    (Embodiment 1)

  Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.

  Referring to FIG. 8, the network system according to the first embodiment of the present invention includes nodes 3001 to 3006, clients 91 to 96, links 81 to 86, and links 21 to 28.

  The functions of the node 3001 are described below.

  (1) The frame arrived from the link 21 or the link 24 is transferred to the link 24 or the link 21.

  (2) A tag (an extension tag or the like) necessary for transfer is added to a frame that has arrived from the link 81, and then transferred to the link 21 or the link 24.

  (3) The frame arrived from the link 21 or the link 24 is transferred to the link 81 after deleting a tag (extension tag or the like) necessary for transfer between nodes.

  (4) In order to construct a spanning tree, control frames (BPDUs) are transmitted / received to / from other nodes.

  Nodes 3002 to 3006 are nodes similar to the node 3001. Hereinafter, the nodes 3001 to 3006 are representatively described using the node 3001, but the description of these nodes 3001 can be similarly realized in the other nodes 3002 to 3006 unless otherwise specified.

  Although only one client terminal is illustrated in FIG. 8, the client 91 may be a set of one or more clients, and has a function of transmitting and receiving frames to and from the node 3001 through the link 81.

  The clients 92 to 96 are client terminals or client groups similar to the client 91. Hereinafter, the client 91 will be described as a representative of the clients 91 to 96, but the description of the client 91 can be similarly applied to the other clients 92 to 96 unless otherwise specified.

  The link 81 is a bidirectional link that connects the client 91 to the node 3001 and the node 3001 to the client 91.

  The links 82 to 86 are the same links as the link 81. Hereinafter, the link 81 will be used as a representative of the links 81 to 86, but the description of the link 81 can be similarly applied to the other links 82 to 86 unless otherwise specified.

  The link 21 is a bidirectional link that connects the node 3001 to the node 3002 and the node 3002 to the node 3001.

  The links 22 to 28 are the same links as the link 21. In the following, description will be made using the link 21 on behalf of the links 22 to 28, but the description of the link 21 can be similarly applied to the other links 22 to 28 unless otherwise specified.

  FIG. 9 is a diagram showing in detail the configuration of the node 3001 constituting the network shown in FIG.

  The node 3001 includes a frame transfer unit 111, a tag insertion unit 112, a tag deletion unit 113, a forwarding table 114, an STP controller 115, a reconfiguration controller 116, a frame sorter 117, and a setting interface 118.

  The frame transfer unit 111 receives the frame received from the link 21 or the link 24 via the frame classifier 117 or the frame received from the tag inserter 112 according to the description content of the forwarding table 114, or the link 21 or the link 24 or the tag. Transfer to the deleter 113.

  The tag inserter 112 transfers the frame received from the client 91 through the link 81 to the frame transfer unit 111 by inserting a tag (extension tag). The received frame can be transferred as it is to the frame transfer unit 111 without inserting a tag (extension tag), and more than one tag (for example, 3500-3508 shown in FIG. Multiple tags that do not contradict each other's relationship), or copy the arrived frame, and one or more same or different tags (extended tags) for each copied frame It is also possible to insert.

  The tag deletion unit 113 is connected to the link 81, removes a tag (extension tag) added to the frame received from the frame transfer unit 111, and transfers the tag to the client through the link 81. Depending on the setting, it is also possible to transfer the received frame to the link 81 as it is without removing the tag (extension).

  The forwarding table 114 responds to an inquiry from the frame transfer unit 111 by sending one or more frame transfer destination ports to the frame transfer unit 111 using one or more combinations as well as a MAC address, a tag, or an input port as a key. To do. The key and the transfer destination port are set by the STP controller 115 and the reconfiguration controller 116.

  The frame discriminator 117 analyzes the frame type of the received frame, and when the frame is a data frame, transfers the frame to the frame transfer unit 111. When the frame is a BPDU, the STP controller 115 re-transmits the frame. If the frame is a reconfiguration control frame, the frame is transferred to the reconfiguration controller 116.

  The STP controller 115 receives the BPDU from the frame discriminator 117, and uses the information included in the Root Identifier field 22055, Root Path Cost field 22056, Bridge Identifier field 22057, and Port Identifier field 22058 in the BPDU, and uses IEEE802.1D / The port information of the spanning tree is updated according to the processing procedure of 1w, a new BPDU is created, and this new BPDU is transmitted to the frame transfer unit 111. The spanning tree controlled by the STP controller 115 is started / stopped by a trigger from the reconfiguration controller 116 or the setting interface 118. The parameters of each spanning tree are set by the setting interface 118.

  The reconfiguration controller 116 receives the reconfiguration control frame from the frame discriminator 117, performs control according to the received reconfiguration control frame, regenerates the control frame as necessary, and sends it to the frame transfer device 111. The reconfiguration control frame is transmitted. Note that the type of reconfiguration control frame and processing corresponding thereto will be described later. In addition, when a BPDU is received from the frame sorter 117, the root node information of the spanning tree is acquired from the information included in the BPDU and held. Details will be described later. Parameter setting and activation trigger related to reconfiguration control are performed via the setting interface 118. In addition, a spanning tree start / stop trigger is given to the STP controller 115 during reconfiguration control. Details of the processing will be described later.

  The setting interface 118 is a trigger for starting / stopping spanning tree input from the network administrator, starting reconfiguration control (node addition request, node deletion request), or a spanning tree parameter or reconfiguration control parameter (timer). Value) to the STP controller 115 and the reconfiguration controller 116. As a form between the input terminal of the network manager and the setting interface 118, there is a case where it is input via a command line interface via a serial connection or a TELNET connection, or a case where a graphic user interface is input from a WEB server or the like. The configuration interface 118 supports each form.

  FIG. 10 is a configuration example of the forwarding table 114 for determining an output port using a tag as a key in FIG. 8 of the present embodiment.

  The tag field 1141 is a field serving as a search index, and it is checked whether the information in this field matches the content written in the tag of the received frame.

  The flag 1142 describes a flag value indicating whether the tag is for current use or for spare use. In the flag 1142, “0” or “1” is described. When the flag is “1”, the tag is currently used. When the flag is “0”, the tag is reserved and the tag to be shared (this implementation) In the example, 4095) means working. Therefore, in the case of “1”, the output port is determined by referring to the entry of the tag, and in the case of “0”, the output port is determined by referring to the entry of the shared tag.

  The output port 1143 is a field that describes a port to which a frame to which the tag is added is to be transferred.

  Note that this embodiment determines not only the tag forwarding that determines the transfer destination port according to the contents of the tag, but also the transfer destination based on the MAC address that has been conventionally used, as shown in this operation example. The same applies to normal MAC address transfer. In this case, a plurality of ports are described in the output port field 1143.

  FIG. 11 is a diagram illustrating in detail the configuration of the reconfiguration controller 116 of the node 3001 in FIG. 8 according to the first embodiment of this invention.

  The reconfiguration controller 116 includes a tag deletion unit 1161, a control frame transmission / reception unit 1162, a tag insertion unit 1163, a reconfiguration processing unit 1164, an extended reconfiguration processing unit 1165, a reconfiguration management table 1166, and a stability timer 1167. It is configured with.

  The control frame transmission / reception unit 1162 transmits / receives a reconfiguration control frame, which is a control frame necessary for tree reconfiguration processing, under the control of the reconfiguration processing unit 1164. The type and content of this control frame will be described later.

  The tag deletion unit 1161 deletes the tag inserted in the control frame input from the frame sorter 117 and transfers the tag to the control frame transmission / reception unit 1162. If no tag is attached to the control frame received from the frame discriminator 117, the received control frame is transferred to the control frame transmission / reception unit 1162 as it is.

  The control frame transmission / reception unit 1162 receives the reconfiguration control frame from the tag deleter 1161 and notifies the reconfiguration processing unit 1164 of information included in the frame. In addition, a reconfiguration control frame (reconfiguration control frame) used in the spanning tree reconfiguration processing is received from the reconfiguration processing unit 1164 and notified to the tag inserter 1163.

  The tag inserter 1163 receives the reconfiguration control frame from the control frame transmission / reception unit 1162, and determines whether the tag is a preset tag (default VLAN tag (for example, a value of “0” or “1”), or a control VLAN tag. The VLAN tag (arbitrary value) prepared as is inserted and transmitted to the frame transfer unit 111. It is also possible to set the frame to be transferred as it is without inserting a tag.

  The reconfiguration processing unit 1164 receives the control frame from which the tag has been deleted by the tag deletion unit 1161 from the control frame transmission / reception unit 1162, and performs processing according to each received control frame. When it is necessary to transfer the control frame to the next node, the control frame with the tag added by the frame transfer unit 111 is transmitted from the reconfiguration processing unit 1164 to the control frame transmission / reception unit 1162 and the tag insertion unit 1163. Forward to the appropriate port and forward to the next node.

  The extended reconfiguration processing unit 1165 exchanges the notification of the start and end of the reconfiguration processing with the reconfiguration processing unit 1164, and transmits the control contents by the reconfiguration processing unit 1164 to the STP controller 115 and other nodes (or other nodes (or Server).

  The reconfiguration management table 1166 is a table for storing information on the usage status of the spare tree used for tree reconfiguration and the tree to be reconfigured.

  When a plurality of timer modes are set by the reconfiguration processing unit 1164 and the time set for each timer mode has elapsed, the stability timer 1167 transmits a timer expiration notification to the reconfiguration processing unit 1164.

  There are four types of timer modes set in the stable timer 1167: timer mode 1 to timer mode 4. These contents will be described in detail in the description of the tree reconstruction process described later.

  In the present invention, in a network constructed by the Spanning Tree Protocol (STP), a new node is added to the network or a node is deleted from the network together with a plurality of spanning trees (working trees) currently undergoing frame transfer. A spare spanning tree (spare tree) is prepared for use in reconfiguring the tree when it is done, and the spare tree is shared in the reconfiguration of each active tree.

  For example, in a VLAN network, it is possible to manage a maximum of 4095 logical trees using a spanning tree protocol.

  In such a network, when a spare tree for tree reconstruction is provided in each spanning tree, management of the current tree is limited to a maximum of 2047 trees.

  In the present invention, it is sufficient to prepare at least one spare tree by adopting a system configuration in which a spare tree is shared by a plurality of active trees. For this reason, a maximum of 4094 (= 4095-1) planes can be prepared. It becomes possible to manage the working tree.

  As an actual network form, for example, a form in which one or several spare trees are provided for several hundred active trees is conceivable. The number of spare trees can be arbitrarily set according to parameters such as the number of active trees, and it is sufficient that at least one spare tree is provided.

  At least one spare tree is prepared, and network reconfiguration is realized by sharing (using) the spare tree when reconfiguring the tree by adding or deleting nodes.

  The following processing is required for network reconfiguration by sharing the spare tree.

  (1) A process for managing the usage status of a spare tree used for tree reconstruction when there is an addition request from a newly added node or a deletion request from a deleted node.

  (2) Processing for managing the state of whether or not the reconfiguration processing of the tree to be reconfigured has been performed and the order of processing when adding and deleting nodes.

  A network system according to a first embodiment of the present invention will be described with reference to the drawings.

  FIG. 12 is a diagram illustrating a configuration of a network system according to the first embodiment. The network configuration is the same as that shown in FIG. 8, and the clients 91 to 96 are omitted here.

  In the first embodiment, the management server 5000 for controlling the sharing of the spare tree, which is used in the reconfiguration of the spanning tree accompanying the addition or deletion of a new server, is provided. The management server 5000 is connected via the setting interface 118 to the STP controller 115 of the node 3001 set as the root node.

  In the first embodiment, (1) processing for managing the usage status of a spare tree used for tree reconstruction, and (2) implementation status of the reconstruction processing of a tree to be reconstructed. The management server 5000 performs processing for managing the processing order.

  The management server 5000 may be provided separately from the nodes constituting the network, or may be realized by giving the function to a node constituting the network (for example, a root node).

The management server 5000 is realized by a program-controlled computer device (CPU) and achieves the functions described below.
It performs the functions described below.

  (1) A function for managing the usage status of a spare tree used for tree reconstruction when there is an addition request from a newly added node or a deletion request from a node.

  In this usage status management, it is confirmed whether or not the spare tree is in use, and the spare tree is secured and released.

  (2) A function for managing the execution status and processing order of a tree to be reconfigured.

  Recognize a tree to be reconstructed and perform control necessary for reconfiguration processing on the root node of the target tree.

  Further, the management server 5000 is provided with a reconfiguration management table 1166 similar to the reconfiguration controller 116 shown in FIG. 12, and necessary information is set in advance.

  An example of setting contents of the reconfiguration management table 1166 of the management server 5000 is shown in FIG.

  In FIG. 13, in the reconfiguration management table 1166, the tree ID 5011 of each active spanning tree and the MAC address 5012 of the root node of each active spanning tree are set in advance. In addition, a reconfiguration processing flag 5013 indicating whether or not the reconfiguration processing of each spanning tree is completed is set. The reconfiguration processing flag 5013 is set as needed in the reconfiguration processing described below.

  Hereinafter, the operation when a new node is added to the network will be described with reference to FIGS.

  Here, as shown in FIG. 14, there are six trees # 4001 to # 4006 as the working tree, and one tree # 4095 is prepared as a spare tree shared by the six working trees. The network system will be described.

  Each of the working trees # 4001 to # 4006 and the protection tree # 4095 before the node is added includes nodes 3001 to 3006, and the state of each spanning tree is indicated by a bold line.

  In the network state shown in FIG. 14, the node 3001 is the root node in the working tree # 4001, the node 3002 is the root node in the working tree # 4002, the node 3003 is the root node in the working tree # 4003, and the node 3004 is in the working tree # 4004. In the root node, the working tree # 4005, the node 3005 is the root node, in the working tree # 4006, the node 3006 is the root node, and in the backup tree # 4095, the node 3001 is the root node.

  Here, processing when a new node # 3012 is added to the network configured as described above as shown in FIG. 15 will be described with reference to the sequence diagram of FIG.

  First, as shown in FIG. 15, addition of a new node 3012 to the working tree # 4001 is executed.

(Step A-1)
Upon receiving the addition request message from the node 3012, the management server 5000 checks the usage state of the spare tree # 4095 (whether use conflicts, which node is used in case of conflict).

  The management server 5000 always recognizes whether the spare tree # 4095 is used for the reconfiguration processing or which working tree is used when it is used. Specifically, a flag for managing the usage status of the spare tree # 4095 (spare tree usage status management flag) is internally managed, and if it is used by any node, the flag = ON, to which node Is not used, flag = OFF. When there is a use request from another node when the flag = ON, a response indicating that the node cannot be used is returned to that node.

(Step A-2)
When the spare tree # 4095 is unused, that is, when the spare tree usage state management flag = OFF, the management server 5000 sets the flag = ON and performs the reconfiguration processing accompanying the addition processing of the node 3012. Reserve tree # 4095. Thereafter, the node 3012 is notified of a message that permits addition to the working tree # 4001.

(Step A-3)
Further, the management server 5000 notifies the root node 3001 of the working tree # 4001 of a message requesting to become the root node of the protection tree # 4095.

(Step A-4)
Upon receiving the request from the management server 5000, the root node 3001 of the working tree # 4001 changes the setting of the priority value of Bridge_ID related to the protection tree # 4095 to a value smaller than the default value. As a result, the root node 3001 becomes the root node of the spare tree # 4095 because the Bridge_ID of the tree # 4095 is smaller than the other nodes. As a result, the state of the spanning tree of the protection tree # 4095 is the same as that of the working tree # 4001, as shown in FIG.

(Step A-5)
As a result, a reconfiguration process (reconfiguration process) for adding a new node 3012 using the spare tree # 4095 is executed in the working tree # 4001. Details of the tree reconfiguration process will be described later.

(Step A-6)
After the reconfiguration processing of the working tree # 4001, the root node 3001 of the working tree # 4001 changes the setting of the priority value of Bridge_ID related to the protection tree # 4095 to the default value. As a result, the root node 3001 returns the Bridge_ID of the tree # 4095 to the normal value, so that the root node of the tree # 4095 returns to the state in which the node having the smallest MAC address is selected among the nodes in the network.

(Step A-7)
Further, the root node 3001 of the working tree # 4001 notifies the management server 5000 of a message indicating that the reconfiguration processing by adding the node 3012 to the working tree # 4001 has been completed.

(Step A-8)
Upon receiving the notification of the completion of the reconfiguration processing, the management server 5000 sets the reconfiguration processing flag 5013 corresponding to the tree ID (# 4001) of the entry 5011 of the reconfiguration management table 5001 to “completed (ON)”. .

  Thereafter, a new node 3012 is added to the current tree # 4002 shown in FIG. 14, which is the next tree.

  The management server 5000 refers to the reconfiguration management table 1166, selects a tree whose reconfiguration processing flag field 5013 is in an unprocessed state, and determines that tree as the next reconfiguration target tree. The determination method when there are a plurality of unprocessed state trees is not particularly limited, but, for example, a method of performing ID in ascending order is conceivable.

  Here, the management server 5000 refers to the reconfiguration management table 1166 and sets the tree # 4002 as the next reconfiguration target tree.

(Step A-9)
The management server 5000 notifies the node 3012 of a message that permits addition to the working tree # 4002.

(Step A-10)
Further, the management server 5000 notifies the root node 3002 of the working tree # 4002 of a message requesting to become the root node of the protection tree # 4095.

(Step A-11)
Accordingly, the root node 3002 of the working tree # 4002 that has received the request from the management server 5000 changes the priority value of the Bridge_ID related to the protection tree # 4095 to a value smaller than the default value. As a result, the root node 3002 becomes the root node of the backup tree # 4095 because the Bridge_ID of the tree # 4095 is smaller than the other nodes. As a result, the state of the spanning tree of the protection tree # 4095 is the same as that of the working tree # 4002.

(Step A-12)
Thereby, in the working tree # 4002, a reconfiguration process (reconfiguration process) for adding a new node 3012 using the spare tree # 4095 is executed. Details of the tree reconfiguration process will be described later.

(Step A-13)
After the reconfiguration processing of the working tree # 4002, the root node 3002 of the working tree # 4002 changes the setting of the priority value of Bridge_ID related to the protection tree # 4095 to the default value. As a result, the root node 3002 returns the Bridge_ID of the tree # 4095 to the normal value, so that the root node of the tree # 4095 returns to the state where the node having the smallest MAC address is selected among the nodes in the network.

(Step A-14)
Further, the root node 3002 of the working tree # 4002 notifies the management server 5000 of a message indicating that the reconfiguration processing by adding the node 3012 to the working tree # 4002 has been completed.

(Step A-15)
Upon receiving the notification of completion of the reconfiguration processing, the management server 5000 sets the reconfiguration processing flag 5013 corresponding to the tree ID (# 4002) of the entry 5011 of the reconfiguration management table 5001 to “completed (ON)”. .

  Thereafter, by repeating the same processing as described above, the processing for adding the node 3012 to the working trees # 4003 to # 4006 is executed.

  Thereafter, the addition process of the node # 3012 to the working trees # 4001 to # 4006 is executed by the same procedure.

  When the addition processing of the node # 3012 to all the working trees # 4001 to # 4006 is completed, the management server 5000 sets the spare tree usage state management flag = OFF and releases the spare tree # 4095. . Thereafter, when there is a request for use of the spare tree # 4095 from another node, the spare tree can be used for the first node.

  The state of the working trees # 4001 to # 4006 to which the node 3012 has been added as described above is shown in FIG.

  In FIG. 16, the processing when node # 3012 is added to the network system has been described. However, processing similar to that of FIG. 16 is also performed when processing a node constituting the network is deleted. The That is, in FIG. 16, a process when a node is deleted by describing “addition (or addition process)” as “deletion (or deletion process)” will be described.

  Next, details of the tree reconstruction process (reconstruction process) in step A-5 will be described with reference to FIGS.

  Processing of a reconfiguration control message used in the tree reconfiguration processing (control message processing in a sequence described later) is handled as follows.

  The frame discriminator 117 that has received the frame analyzes the received frame and transfers it to the STP controller 115 and the reconfiguration controller 116 if it is a BPDU, and transfers it to the reconfiguration controller 116 if it is a reconfiguration control message.

  In the reconfiguration controller 116, the control frame transmission / reception unit 1162 transfers the control frame from which the tag is deleted by the tag deletion unit 1161 to the reconfiguration processing unit 1164. In the reconfiguration processing unit 1164, after performing processing according to each control frame, when it is necessary to transfer to the next node, the reconfiguration processing unit 1164 passes through the control frame transmission / reception unit 1162 and the tag inserter 1163, The control frame to which the tag is added is transferred to an appropriate port by the frame transfer unit 111 and transferred to the next node.

Here, the reconfiguration control message used in the spanning tree reconfiguration processing will be described. The reconfiguration control message is composed of the following five types of messages.
(1) Topology change application message This topology change application message includes 1) topology change application message 1 (application for topology change of spare tree) and 2) topology change application message 2 (topology change application of new spare tree) Application).

(2) Topology change application response message This topology change application response message includes, as a response to the application message, 1) a changeable response, 2) an unchangeable response, and 3) a non-reconfigurable response.

(3) Topology change response confirmation message This message notifies the confirmation that the change is received when the topology change application response message is a changeable response.

(4) Switching message This switching message includes 1) switching message 1 (standby = even tag, working = switching trigger to odd tag), 2) switching message 2 (working = even tag, spare = odd tag) Switching trigger).

(5) STP instance start / stop request message This message is used to request each edge node to start / stop the spanning tree with the specified ID.

(Tree reconstruction by adding nodes)
A reconfiguration process when an additional node 3012 is added to the working tree # 4001 in which the node 3001 is the root node as shown in FIG. 15 will be described with reference to the sequence diagram of FIG.

  Here, the node 3001 is the root node in both the working tree # 4001 and the backup tree # 4095 by the processing shown in FIG.

  FIG. 20 shows the contents of the timer mode of the stability timer 1167. Here, there are timer mode 1 to timer mode 4, and the type of node using each timer mode, the activation trigger indicating the timing at which the timer mode is set, and the purpose of use thereof are shown.

(Step B-1: Additional node 3012)
In the additional node 3012, the reconfiguration processing unit 1164 of the reconfiguration controller 116 receives a reconfiguration control activation trigger for adding a node from the setting interface 118 or the extended reconfiguration processing unit 1165. In the reconfiguration control activation trigger, the ID of the tree to be activated is specified by [Tag].

  (1) When the own node ID is specified in the [tag] specified by the reconfiguration control start trigger, the reconfiguration processing unit 1164 starts the STP instance of the specified [tag] to the STP controller 115 Notify instructions to do.

  In addition, an STP instance start / stop request message indicating a request for adding an STP for the specified [tag] is broadcast to other nodes.

  (2) When the [tag] specified by the reconfiguration control activation trigger does not match the own node ID, the reconfiguration processing unit 1164 starts the reconfiguration processing described below.

(Step B-2: Each node in the network)
Upon receiving the STP instance start / stop request message, the reconfiguration processing unit 1164 of each node in the network notifies the STP controller 115 of an instruction to create the notified [Tag] STP instance.

(Step B-3: Additional node 3012)
The reconfiguration processing unit 1164 of the additional node 3012 only performs reception processing of the BPDU transferred from the frame discriminator 117, and from the information stored in the received BPDU, the spanning tree ID from the VLAN tag value, The MAC address of the root node of the tree is acquired from Bridge_ID, and each information is held in the reconfiguration management table 1166 shown in FIG.

(Step B-4: Additional node 3012)
In step B-3, the reconfiguration processing unit 1164 of the additional node 3012 acquires the MAC address of the root node 3001 from the reconfiguration management table 1166, and unicasts the topology change application message 1 to the root node 3001. .

  If the MAC address of the root node 3001 does not exist in the reconfiguration management table 1166, the process waits until it can be acquired in step B-3.

  In order to improve reliability, the topology change application message 1 is sent every predetermined time (here, X seconds) until the response message 1 is received in preparation for discarding the topology change application message 1 at the transfer destination. Transmit a plurality of times (here, the maximum number of transmissions is Y).

(Step B-5: root node 3001)
When receiving the topology change application message 1, the reconfiguration processing unit 1164 of the root node 3001 determines whether or not the reconfiguration process is possible, and transmits a topology change application response message 1 including the determination result to the node 3012 to be added. .

  Here, (1) if the [tag] tree specified in the topology change application message 1 is not the tree whose root is the local node, the topology change application response message 1 stating that “reconfiguration is not allowed” Is transmitted to the node 3012 that is the transmission source of the topology change application message 1.

  (2) If the [Tag] tree specified in the topology change application message 1 is a tree whose root is the current node and is not being reconfigured by an application from another node, it is “changeable”. A topology change application response message 1 to the effect is transmitted to the node 3012 that is the transmission source of the topology change application message 1.

  The timer mode 1 of the stability timer 1167 is activated.

  At the same time, the reconfiguration processing acceptance flag managed by the root node is set to “ON”.

  The reconfiguration process acceptance flag is a flag for performing the reconfiguration process only for the application of the reconfiguration process from one node. While this reconfiguration process reception flag is ON, The root node 3001 means that reconfiguration processing from other nodes is not accepted. In this example, only node addition processing from the node 3012 is performed, and addition processing and deletion processing from nodes other than the node 3012 are not accepted until the processing ends.

  (3) If the [Tag] tree specified in the topology change application message 1 is a tree whose root is the current node and is being reconfigured from another node, the topology indicating that it cannot be changed A change application response message 1 is transmitted.

(Step B-6: Additional node 3012)
The reconfiguration processing unit 1164 of the node 3012 to be added performs processing for receiving the topology change application response message 1 from the root node 3001.

  (1) Topology change application response message 1 (MAC_DA = determined by its own MAC address) for topology change application message 1 sent by itself arrives within a predetermined time (X seconds) after transmission of topology change application message 1 In such a case, the following processing is performed according to the contents of the topology change application response message 1.

(A) In the case of “changeable” A response confirmation message is transmitted to the root node 3001.

  Timer mode 1 is activated for the stable timer 1167.

  Reconstruction of the spare tree (processing after step B-7) is started.

(B) In the case of “cannot be changed” Timer mode 4 is activated for the stable timer 1167.

  When the completion notification of the timer mode 4 is received from the stability timer 1167, the topology change application message 1 is retransmitted (return to step B-4).

(C) In the case of “non-reconfigurable”
The reconfiguration processing ends abnormally, and the reconfiguration processing unit 1164 notifies the extended reconfiguration processing unit 1165 to that effect.

  (2) If the topology change application response message 1 does not arrive within X seconds after transmission, the following processing is performed according to the number of times the topology change application message 1 is transmitted.

(A) When the number of transmissions is Y or less The application message 1 is retransmitted X seconds after the transmission of the topology change application message 1 (return to step B-4).

(B) When the number of transmissions exceeds Y times Timer mode 4 is activated for the stable timer 1167.

  When the completion notification of the timer mode 4 is received from the stability timer 1167, the topology change application message 1 is retransmitted (return to step B-4). In this case, the upper limit number of retransmissions until the reconstruction process is abnormally terminated is set to a predetermined value (here, B times).

  If the response message 1 does not arrive within X seconds even when the topology change application message 1 is retransmitted and the number of retransmissions exceeds B times, the reconfiguration process is terminated abnormally, and the extended reconfiguration process This is notified to the unit 1165.

(Step B-7: Additional node 3012)
In Step B-6, when the content of the topology change application response message 1 is “changeable”, the reconfiguration processing unit 1164 of the additional node 3012 sends the spare tree (tree ID = # 4095) to the STP controller 115. An instruction to create an STP instance is notified.

  As a result, an STP instance with [tag] = “4095” is created in the STP controller 115, and transmission of a BPDU with [tag] = “4095” is started. As a result, a spanning tree including the node 3012 is reconfigured in the network.

(Step B-8: root node 3001)
In the root node 3001, when the completion notification of the timer mode 1 is received from the stability timer 1167, the reconfiguration processing unit 1164 detects the stability of the protection tree # 4095.

  If the response confirmation message is received from the additional node 3012 before the completion of the timer mode 1, the reconfiguration processing unit 1164 changes the spare tree # 4095 from the spare to the current, and the tree # 4001 from the current. In order to change to the spare, the switching message 1 is broadcasted to each node in the network.

  If the response confirmation message is not received from the additional node 3012 before the completion of the timer mode 1, the reconfiguration processing unit 1164 resets the timer mode 1 to the stable timer 1167, ends the reconfiguration processing, and extends This is notified to the reconfiguration processing unit 1165.

(Step B-9: additional node 3012 and each node in the network)
In each node in the network including the additional node 3012, the reconfiguration processing unit 1164 performs the switching message 1 reception process.

  Upon receiving the switching message 1, the reconfiguration processing unit 1164 rewrites the reconfiguration management table 1166 so that the tag “4095” = active and the tag “4001” = reserve.

  Further, the output port for the tag “4001” in the forwarding table 114 is rewritten so as to refer to the entry of the tag “4095”. That is, regarding the entry of the tag “4001” in the forwarding table 114, the value of the flag field 1142 is set to 0. As a result, the tag “4001” is reserved, and the output port is determined with reference to the entry of the tag “4095”. Thereafter, the data frame is transferred on the transfer path of the tree # 4095.

  Further, in the additional node 3012, the reconfiguration processing unit 1164 activates timer mode 2 for the stable timer 1167.

  When the completion notification of the timer mode 2 is received from the stability timer 1167, an application message 2 is transmitted to the root node 3001 (the frame flowing on the old working tree (# 4001) is waited for the time of the timer mode 2). Guarantee that it will not exist).

(Step B-10: Additional node 3012)
After the application message 2 is transmitted, the reconfiguration processing unit 1164 of the additional node 3012 notifies the STP controller 115 of an instruction for creating an STP instance of the protection tree (# 4001).

  By creating an STP instance of [tag] = “4001” in the STP controller 115, transmission of a BPDU including [tag] = “4001” as control information is started in the additional node 3012.

(Step B-11: root node 3001)
When receiving the application message 2, the reconfiguration processing unit 1164 of the root node 3001 starts timer mode 1 for the stability timer 1167.

(Step B-12: root node 3001)
Further, when the reconfiguration processing unit 1164 of the root node 3001 receives the completion notification of the timer mode 1 from the stability timer 1167, the reconfiguration processing unit 1164 detects the stability of the tree # 4001, and changes the tree # 4095 from the standby to the current one. In order to change from active to spare, a switch message 2 is broadcast to each node in the network. In addition, the timer mode 3 is started for the stability timer 1167 (by waiting in the timer 3 mode, it is ensured that no data frame remains in the tree # 4095).

(Step B-13: additional node 3012 and each node in the network)
The reconfiguration processing unit 1164 of each node in the network including the additional node 3012 performs switching message 2 reception processing.

  The reconfiguration processing unit 1164 rewrites the reconfiguration management table 1166 with the tag “4001” = active and the tag “4095” = reserve.

  In addition, the output port for the tag “4001” in the forwarding table 114 is rewritten to refer to the entry of the tag “4001”. That is, the value of the flag field 1142 is set to 1 for the entry of the tag “4001” in the forwarding table 114. As a result, the tag “4001” becomes active, and the output port is determined with reference to the entry of the tag “4001”. Thereafter, the data frame is transferred on the transfer path of the tree # 4001.

  In the additional node 3012, the reconfiguration processing unit 1164 notifies the extended reconfiguration processing unit 1165 of the normal end of the reconfiguration processing.

(Step B-14: root node 3001)
When the reconfiguration processing unit 1164 of the root node 3001 receives the completion notification of the timer mode 3 from the stability timer 1167, the reconfiguration processing reception flag is set to “OFF”. Thereafter, other nodes (VLAN pairs) can be added / deleted.

(Tree reconstruction by deleting nodes)
The reconfiguration process when the node 3012 is deleted from the tree # 4001 in which the node 3001 is the root node as shown in FIG. 18 will be described with reference to the sequence diagram of FIG.

  Here, tree # 4001 is the working tree, and tree # 4095 is the spare tree. Node 3001 is the root node of both trees.

(Step C-1: Delete node 3012)
The reconfiguration processing unit 1164 of the deletion node 3012 receives a reconfiguration control activation trigger for node deletion from the setting interface 118 or the extended reconfiguration processing unit 1165. In the reconfiguration control activation trigger, the ID of the tree for which deletion processing is to be activated is specified by [tag] as in the case of adding a node.

  (1) When the [tag] specified by the reconfiguration control activation trigger is its own node ID, the reconfiguration processing unit 1164 notifies the STP controller 115 of an instruction to stop the STP instance of the specified [tag]. To do.

In addition, an STP instance start / stop request message indicating a request to stop the STP instance of the specified [tag] is broadcast to other nodes.
(2) When the [tag] specified by the activation trigger does not match the own node ID, the reconfiguration processing unit 1164 starts the subsequent reconfiguration processing.

(Step C-2: Each node in the network)
When receiving the STP instance start / stop request message, the reconfiguration processing unit 1164 of each node in the network notifies the STP controller 115 of an instruction to stop the STP instance of the notified [tag].

(Step C-3: Delete node 3012)
After receiving the reconfiguration control activation trigger, the reconfiguration processing unit 1164 of the deletion node 3012 acquires the MAC address of the root node 3001 from the reconfiguration management table 1166, and sends the topology change application message 1 to the root node 3001. Cast transfer.

  However, if the MAC address of the root node 3001 is not in the reconfiguration management table 1166, the BPDU of the tag 3001 of the target tag pair is received, and the process waits until the MAC address of the root node can be acquired.

  As in the case of the reconfiguration process for adding a node, in order to improve reliability, the topology change application message 1 is kept until the response message 1 is received in preparation for discarding the topology change application message 1 at the transfer destination. Transmission is performed a plurality of times (here, the maximum number of transmissions is Y times) every predetermined time (here, X seconds).

(Step C-4: root node 3001)
When receiving the topology change application message 1, the reconfiguration processing unit 1164 of the root node 3001 determines whether or not the reconfiguration processing is possible, and transmits a topology change application response message 1 including the determination result to the node 3012 to be deleted. .

  (1) If the tree of [Tag] specified in the topology change application message 1 is not a tree whose root is the local node, a topology change application response message 1 indicating “unavailable for reconfiguration” is transmitted. .

  (2) If the [Tag] tree specified in the topology change application message 1 is a tree whose root is the current node and is not being reconfigured by an application from another node, it is “changeable”. A topology change application response message 1 is transmitted.

  The timer mode 1 of the stability timer 1167 is activated.

  The reconfiguration process acceptance flag is set to “ON”.

  (3) If the [Tag] tree specified in the topology change application message 1 is a tree whose root is the current node and is being reconfigured from another node, the topology indicating that it cannot be changed A change application response message 1 is transmitted.

(Step C-5: Delete node 3012)
The reconfiguration processing unit 1164 of the node 3012 to be deleted performs processing for receiving the topology change application response message 1 from the root node 3001.

  (1) Topology change application response message 1 (MAC_DA = determined by its own MAC address) for topology change application message 1 sent by itself arrives within a predetermined time (X seconds) after transmission of topology change application message 1 In such a case, the following processing is performed according to the contents of the topology change application response message 1.

(A) In the case of “changeable” A response confirmation message is transmitted to the root node 3001.

  Timer mode 1 is activated for the stable timer 1167.

  Reconstruction of the spare tree (processing after step C-6) is started.

(B) In the case of “cannot be changed” Timer mode 4 is activated for the stable timer 1167.

  When the completion notification of the timer mode 4 is received from the stability timer 1167, the topology change application message 1 is retransmitted (return to step C-3).

(C) In the case of “unable to reconfigure” The reconfiguration processing is terminated abnormally, and the reconfiguration processing unit 1164 notifies the extended reconfiguration processing unit 1165 to that effect.

  (2) If the topology change application response message 1 does not arrive within X seconds after transmission, the following processing is performed according to the number of times the topology change application message 1 is transmitted.

(A) When the number of transmissions is Y or less The application message 1 is retransmitted X seconds after the transmission of the topology change application message 1 (return to step C-3).

(B) When the number of transmissions exceeds Y times Timer mode 4 is activated for the stable timer 1167.

  When the completion notification of the timer mode 4 is received from the stability timer 1167, the topology change application message 1 is retransmitted (return to step C-3). In this case, the upper limit number of retransmissions until the reconstruction process is abnormally terminated is set to a predetermined value (here, B times).

  If the response message 1 does not arrive within X seconds even when the topology change application message 1 is retransmitted and the number of retransmissions exceeds B times, the reconfiguration process is terminated abnormally, and the extended reconfiguration process This is notified to the unit 1165.

(Step C-6: Delete node 3012)
In Step C-5, when the content of the topology change application response message 1 is “changeable”, the reconfiguration processing unit 1164 of the deletion node 3012 sends the spare tree (tree ID = # 4095) to the STP controller 115. An instruction to stop the STP instance is notified.

  As a result, the STP instance with [tag] = “4095” is deleted from the STP controller 115, and the transmission of the BPDU with [tag] = “4095” is stopped. As a result, a spanning tree excluding the node 3012 is reconfigured in the network.

(Step C-7: root node 3001)
In the root node 3001, when the completion notification of the timer mode 1 is received from the stability timer 1167, the reconfiguration processing unit 1164 detects the stability of the tree # 4095.

  If the response confirmation message is received from the node 3012 to be deleted before the completion of the timer mode 1, the reconfiguration processing unit 1164 changes the tree # 4095 from the standby to the current, and the tree # 4001 from the current. In order to change to the spare, the switching message 1 is broadcasted to each node in the network.

  If the response confirmation message is not received from the additional node 3012 before the completion of the timer mode 1, the reconfiguration processing unit 1164 resets the timer mode 1 to the stable timer 1167, ends the reconfiguration processing, and extends This is notified to the reconfiguration processing unit 1165.

(Step C-8: Delete node 3012 and each node in the network)
In each node in the network including the node 3012 to be deleted, the reconfiguration processing unit 1164 performs the switching message 1 reception process.

  Upon receiving the switching message 1, the reconfiguration processing unit 1164 rewrites the reconfiguration management table 1166 so that the tag “4095” = active and the tag “4001” = reserve.

  Further, the output port for the tag “4001” in the forwarding table 114 is rewritten so as to refer to the entry of the tag “4095”. That is, regarding the entry of the tag “4001” in the forwarding table 114, the value of the flag field 1142 is set to 0. As a result, the tag “4001” is reserved, and the output port is determined with reference to the entry of the tag “4095”. Thereafter, the data frame is transferred on the transfer path of the tree # 4095.

  Further, in the node 3012 to be deleted, the reconfiguration processing unit 1164 activates the timer mode 2 for the stability timer 1167.

  When the completion notification of the timer mode 2 is received from the stability timer 1167, an application message 2 is transmitted to the root node 3001 (the frame flowing on the old working tree (# 4001) is waited for the time of the timer mode 2). Guarantee that it will not exist).

(Step C-9: Delete node 3012)
After transmitting the application message 2, the reconfiguration processing unit 1164 of the deletion target node 3012 notifies the STP controller 115 of an instruction to stop the STP instance of the backup tree (# 4001).

  By deleting the STP instance with [tag] = “4001” from within the STP controller 115, the deletion node 3012 stops the transmission of the BPDU with [tag] = “4001”.

(Step C-10: root node 3001)
When receiving the application message 2, the reconfiguration processing unit 1164 of the root node 3001 starts timer mode 1 for the stability timer 1167.

(Step C-11: root node 3001)
Further, when the reconfiguration processing unit 1164 of the root node 3001 receives the completion notification of the timer mode 1 from the stability timer 1167, the reconfiguration processing unit 1164 detects the stability of the tree # 4001, and changes the tree # 4095 from the standby to the current one. In order to change from active to spare, a switch message 2 is broadcast to each node in the network. In addition, the timer mode 3 is started for the stability timer 1167 (by waiting in the timer 3 mode, it is ensured that no data frame remains in the tree # 4095).

(Step C-12: additional node 3012 and each node in the network)
The reconfiguration processing unit 1164 of each node in the network including the deletion target node 3012 performs the switching message 2 reception process.

  The reconfiguration processing unit 1164 rewrites the reconfiguration management table 1166 with the tag “4001” = active and the tag “4095” = reserve.

  In addition, the output port for the tag “4001” in the forwarding table 114 is rewritten to refer to the entry of the tag “4001”. That is, the value of the flag field 1142 is set to 1 for the entry of the tag “4001” in the forwarding table 114. As a result, since the tag “4001” is currently used, the output port is determined with reference to the entry of the tag “4001”. Thereafter, the data frame is transferred on the transfer path of the tree # 4001.

  In the deletion target node 3012, the reconfiguration processing unit 1164 notifies the extended reconfiguration processing unit 1165 of the normal end of the reconfiguration processing.

(Step C-13: root node 3001)
When the reconfiguration processing unit 1164 of the root node 3001 receives the completion notification of the timer mode 3 from the stability timer 1167, the reconfiguration processing reception flag is set to “OFF”. Thereafter, other nodes (VLAN pairs) can be added / deleted.

  By performing the tree reconfiguration process as described above, the spanning tree is reconfigured without stopping the network.

  In a conventional network system that does not use a spare tree, packet loss due to tree reconfiguration occurs when a new node is added or deleted due to equipment maintenance, replacement, or network enhancement. However, there was a possibility of affecting traffic during service. Therefore, it is necessary to obtain permission for the user to perform such network reconfiguration work, or work in the middle of the night or on holidays when there is little traffic during service to minimize the impact on the user. There was a need to do. As a result, there is a problem that the network operation cost increases. According to the present embodiment, since it is not necessary to stop the network, network reconfiguration work can be performed without being limited by time, and the network operation cost can be greatly reduced.

  The effect of the first embodiment will be described. According to the first embodiment, as described above, the spanning tree can be reconfigured without stopping the network when the network configuration is changed, and the number of spanning trees that can be used in the network is halved. The effect that the number of usable spanning trees can be expanded to the maximum number of spanning trees −1 is realized. In addition, since the number of control frames for controlling the spanning tree can be reduced, it is possible to reduce the processing load required for processing the control frames in each node.

(Second Embodiment)
Next, a network system according to the second embodiment of the present invention will be described.

  In the second embodiment, the server manages the usage state of the spare tree, and the tree management in adding and deleting nodes is performed by the nodes that are added to or deleted from the network.

  The network configuration according to the second embodiment is the same as the configuration shown in FIG. 12, but is different from the first embodiment in that the management server 5000 does not include the reconfiguration management table 1166.

  The node 3012 that is added to or deleted from the network performs reception processing of BPDUs flowing on the network before starting the reconfiguration of the tree, and from the information stored in the received BPDUs, the VLAN tag value 13 is created, and the MAC address of the root node of the tree is obtained from Bridge_ID, thereby creating the reconfiguration management table 1166 shown in FIG.

  Hereinafter, an operation when a node is added will be described with reference to FIG.

  Here, as shown in FIG. 14, there will be described a network system in which six trees of working trees # 4001 to # 4006 exist and one spare tree # 4095 shared by the six working trees is prepared.

  Each of the working trees # 4001 to # 4006 and the protection tree # 4095 before the node is added includes nodes 3001 to 3006, and the state of each spanning tree is indicated by a bold line.

  In the network state shown in FIG. 14, the node 3001 is in the working tree # 4001, the node 3002 is in the working tree # 4002, the node 3003 is in the working tree # 4003, the node 3004 is in the working tree # 4004, and the node is in the working tree # 4005. In the node 3005 and the working tree # 4006, the node 3006 is a root node, and in the backup tree # 4095, the node 3001 is a root node.

  Here, processing when a new node # 3012 is added to the network configured as described above as shown in FIG. 15 will be described with reference to the sequence diagram of FIG.

  First, as shown in FIG. 15, addition of a new node 3012 to the working tree # 4001 is executed.

(Step D-1)
The addition request message is transmitted from the newly added node 3012 to the root node 3001 of the working tree # 4001, thereby requesting addition to the tree.

(Step D-2)
Upon receipt of the addition request message from the node 3012, the root node 3001 of the working tree # 4001 uses the management server 5000 to determine whether the spare tree # 4095 is used (whether use conflicts or which node is conflicted). Inquires about whether or not

(Step D-3)
The management server 5000 uses the spare tree usage state management flag to indicate whether the spare tree # 4095 is used for reconfiguration processing or which working tree is being used. If the management tree management state management flag is OFF, the flag = ON is set, and the spare tree # 4095 is secured for the reconfiguration process accompanying the addition process of the node 3012. Thereafter, the root node 3001 is permitted to add to the working tree # 4001, and the root node 3001 is notified of a message requesting to become the root node of the protection tree # 4095.

(Step D-4)
Upon receiving the request from the management server 5000, the root node 3001 of the working tree # 4001 changes the setting of the priority value of Bridge_ID related to the protection tree # 4095 to a value smaller than the default value. As a result, the root node 3001 becomes the root node of the spare tree # 4095 because the Bridge_ID of the tree # 4095 is smaller than the other nodes. As a result, the state of the spanning tree of the protection tree # 4095 is the same as that of the working tree # 4001, as shown in FIG.

(Step D-5)
As a result, a reconfiguration process (reconfiguration process) for adding a new node 3012 using the spare tree # 4095 is executed in the working tree # 4001. The tree reconstruction process is the same as the process of FIGS. 19 and 21 described in the first embodiment.

(Step D-6)
After the reconfiguration processing of the working tree # 4001, the root node 3001 of the working tree # 4001 changes the setting of the priority value of Bridge_ID related to the protection tree # 4095 to the default value. As a result, the root node 3001 returns the Bridge_ID of the tree # 4095 to the normal value, so that the root node of the tree # 4095 returns to the state in which the node having the smallest MAC address is selected among the nodes in the network.

(Step D-7)
Further, the root node 3001 of the working tree # 4001 notifies the management server 5000 of a message indicating that the reconfiguration processing by adding the node 3012 to the working tree # 4001 has been completed.

(Step D-8)
When the management server 5000 receives the notification of the completion of the reconfiguration processing, it sets the backup tree usage state management flag to flag = OFF and enables the backup tree # 4095 to be used for additional deletion processing of other nodes.

  When the reconfiguration processing of the tree is completed, the additional node 3012 sets the reconfiguration processing flag 5013 of the tree for which the reconfiguration processing has ended to “completed” with respect to the reconfiguration management table 1166, and the reconfiguration processing flag 5013 is set to ON. After selecting a tree that is OFF, addition of a new node 3012 to the current tree # 4002 shown in FIG. 14, which is the next tree, is executed. In addition, there is no restriction | limiting in particular about the determination method in case there exist multiple unprocessed state trees.

(Step D-9)
A request for addition to the tree is made by transmitting an addition request message from the newly added node 3012 to the root node 3002 of the working tree # 4002.

(Step D-10)
Upon receiving the addition request message from the node 3012, the root node 3002 of the working tree # 4002 uses the management tree 5000 with respect to the use state of the spare tree # 4095 (whether use conflicts or which node if there is a conflict). Inquires about whether or not

(Step D-11)
When the spare tree use state management flag = OFF, the management server 5000 sets the flag = ON, and reserves the spare tree # 4095 for the reconfiguration process accompanying the addition process of the node 3012. Thereafter, the root node 3002 is permitted to be added to the working tree # 4002, and the root node 3002 is notified of a message requesting to become the root node of the protection tree # 4095.

(Step D-12)
In response to the request from the management server 5000, the root node 3002 of the working tree # 4002 changes the setting of the priority value of Bridge_ID related to the protection tree # 4095 to a value smaller than the default value. As a result, the root node 3002 becomes the root node of the backup tree # 4095 because the Bridge_ID of the tree # 4095 is smaller than the other nodes. As a result, the state of the spanning tree of the protection tree # 4095 is the same as that of the working tree # 4002.

(Step D-13)
Thereby, in the working tree # 4002, a reconfiguration process (reconfiguration process) for adding a new node 3012 using the spare tree # 4095 is executed. The tree reconstruction process is the same as the process described in the first embodiment.

(Step D-14)
After the reconfiguration processing of the working tree # 4002, the root node 3002 of the working tree # 4002 changes the setting of the priority value of Bridge_ID related to the protection tree # 4095 to the default value. As a result, the root node 3002 returns the Bridge_ID of the tree # 4095 to the normal value, so that the root node of the tree # 4095 returns to the state where the node having the smallest MAC address is selected among the nodes in the network.

(Step D-15)
Further, the root node 3002 of the working tree # 4002 notifies the management server 5000 of a message indicating that the reconfiguration processing by adding the node 3012 to the working tree # 4002 has been completed.

(Step D-16)
When the management server 5000 receives the notification of the completion of the reconfiguration processing, it sets the backup tree usage state management flag to flag = OFF and enables the backup tree # 4095 to be used for additional deletion processing of other nodes.

  In the reconfiguration management table 1166, the additional node 3012 sets the reconfiguration processing flag 5013 of the tree for which the reconfiguration processing has ended to “already (ON)” and selects a tree for which the reconfiguration processing flag 5013 is OFF. Thereafter, the addition of a new node 3012 to the next tree is performed.

  Thereafter, by repeating the same processing as described above, the additional processing of the node 3012 is executed for the remaining working trees # 4003 to # 4006.

  The state of the working trees # 4001 to # 4006 to which the node 3012 has been added as described above is shown in FIG.

  In FIG. 22, the processing when the node # 3012 is added to the network system has been described. However, the processing similar to that of FIG. 22 is also performed when the node configuring the network is deleted. The That is, in FIG. 22, “addition (or addition processing)” is described as “deletion (or deletion processing)”, and processing when a node is deleted will be described.

  The effect of the second embodiment will be described. According to the second embodiment, as in the first embodiment, the spanning tree can be reconfigured without stopping the network when the network configuration is changed, and the number of spanning trees that can be used in the network. The conventional problem that is limited to 1/2 is avoided, and the effect that the number of usable spanning trees can be expanded to the maximum number of spanning trees −1 is realized. In addition, since the number of control frames for controlling the spanning tree can be reduced, it is possible to reduce the processing load required for processing the control frames in each node.

(Third embodiment)
Next, a network system according to the third embodiment of the present invention will be described.

  In the third embodiment, the management of the use status of the spare tree and the tree management in adding and deleting nodes are both performed by nodes added to or deleted from the network. Yes. That is, the node to be added or deleted has the function of the management server 5000 shown in the first embodiment.

  Therefore, the network configuration is a configuration in which the management server is omitted from the configuration of FIG.

  The node 3012 that is added to or deleted from the network performs reception processing of BPDUs flowing on the network before starting the reconfiguration of the tree, and from the information stored in the received BPDUs, the VLAN tag value 13 is created, and the MAC address of the root node of the tree is obtained from Bridge_ID, thereby creating the reconfiguration management table 1166 shown in FIG.

  Hereinafter, an operation when a node is added will be described with reference to FIG.

  Here, as shown in FIG. 14, there will be described a network system in which six trees of working trees # 4001 to # 4006 exist and one spare tree # 4095 shared by the six working trees is prepared.

  Each of the working trees # 4001 to # 4006 and the protection tree # 4095 before the node is added includes nodes 3001 to 3006, and the state of each spanning tree is indicated by a bold line.

  In the network state shown in FIG. 14, the node 3001 is in the working tree # 4001, the node 3002 is in the working tree # 4002, the node 3003 is in the working tree # 4003, the node 3004 is in the working tree # 4004, and the node is in the working tree # 4005. In the node 3005 and the working tree # 4006, the node 3006 is a root node, and in the backup tree # 4095, the node 3001 is a root node.

  Here, processing when a new node # 3012 is added to the network configured as described above as shown in FIG. 15 will be described with reference to the timing chart of FIG.

  First, as shown in FIG. 15, addition of a new node # 3012 to the working tree # 4001 is executed.

(Step E-1)
The added node 3012 notifies the working trees # 4001 to # 4006 in the network of the use of the spare tree # 4095 by broadcasting.

(Step E-2)
If a notification indicating that the spare tree # 4095 is in use is not received from other nodes (nodes of all the working trees # 4001 to # 4006) after a certain period of time has passed, each working tree # 4001 to # 4006 in the network is notified. On the other hand, the reservation of the reserve tree # 4095 is notified by broadcasting.

(Step E-3)
With respect to the reconfiguration management table 1166, the additional node 3012 selects a tree whose reconfiguration processing flag 5013 is OFF (in this case, tree # 4001), and then adds an additional request message to the root node 3001 of the working tree # 4001. To request addition to the tree.

(Step E-4)
Upon receiving an addition request message from the addition node 3012, the root node 3001 of the working tree # 4001 changes the setting of the priority value of Bridge_ID related to the protection tree # 4095 to a value smaller than the default value. As a result, the root node 3001 becomes the root node of the spare tree # 4095 because the Bridge_ID of the tree # 4095 is smaller than the other nodes. As a result, the state of the spanning tree of the protection tree # 4095 is the same as that of the working tree # 4001, as shown in FIG.

(Step E-5)
As a result, a reconfiguration process (reconfiguration process) for adding a new node 3012 using the spare tree # 4095 is executed in the working tree # 4001. The tree reconstruction process is the same as the process described in the first embodiment.

(Step E-6)
After the reconfiguration process of the working tree # 4001 is completed, the root node 3001 of the working tree # 4001 returns the Bridge_ID of the protection tree # 4095 to the initial value.

  After the reconfiguration processing of the working tree # 4001, the root node 3001 of the working tree # 4001 changes the setting of the priority value of Bridge_ID related to the protection tree # 4095 to the default value. As a result, the root node 3001 returns the Bridge_ID of the tree # 4095 to the normal value, so that the root node of the tree # 4095 returns to the state in which the node having the smallest MAC address is selected among the nodes in the network.

(Step E-7)
Furthermore, the root node 3001 of the working tree # 4001 notifies the addition node 3012 that the addition of the node 3012 to the working tree # 4001 has been completed.

(Step E-8)
When the additional node 3012 receives the notification of the completion of the reconfiguration processing, the reconfiguration processing flag 5013 corresponding to the tree ID (# 4001 in this case) of the entry 5011 of the reconfiguration management table 5001 is set to “completed (ON)”. Set. Further, the spare tree usage state management flag is set to flag = OFF, so that the spare tree # 4095 can be used for additional deletion processing of other nodes.

  In the reconfiguration management table 1166, the additional node 3012 sets the reconfiguration processing flag 5013 of the tree for which the reconfiguration processing has ended to “already (ON)” and selects a tree for which the reconfiguration processing flag 5013 is OFF. Thereafter, a new node 3012 is added to the current tree # 4002 shown in FIG. 14 which is the next tree.

(Step E-9)
The addition request message is transmitted from the added node 3012 to the root node 3002 of the working tree # 4002 in which the reconfiguration processing flag 5013 is OFF, thereby requesting addition to the tree.

(Step E-10)
When receiving the addition request message from the addition node 3012, the root node 3002 of the working tree # 4002 changes the setting of the priority value of Bridge_ID related to the protection tree # 4095 to a value smaller than the default value. As a result, the root node 3002 becomes the root node of the backup tree # 4095 because the Bridge_ID of the tree # 4095 is smaller than the other nodes. As a result, the state of the spanning tree of the protection tree # 4095 is the same as that of the working tree # 4002.

(Step E-11)
Thereby, in the working tree # 4002, a reconfiguration process (reconfiguration process) for adding a new node 3012 using the spare tree # 4095 is executed. The tree reconstruction process is the same as the process of FIGS. 19 and 21 described in the first embodiment.

(Step E-12)
After the reconfiguration process of the working tree # 4002, the root node 3002 of the working tree # 4002 returns the Bridge_ID of the protection tree # 4095 to the initial value.

  After the reconfiguration processing of the working tree # 4002, the root node 3002 of the working tree # 4002 changes the setting of the priority value of Bridge_ID related to the protection tree # 4095 to the default value. As a result, the root node 3002 returns the Bridge_ID of the tree # 4095 to the normal value, so that the root node of the tree # 4095 returns to the state where the node having the smallest MAC address is selected among the nodes in the network.

(Step E-13)
Furthermore, the root node 3002 of the working tree # 4002 notifies the addition node 3012 that the addition to the working tree # 4002 has been completed.

(Step E-14)
Upon receiving the notification of the completion of the reconfiguration processing, the additional node 3012 sets the reconfiguration processing flag 5013 corresponding to the tree ID (# 4002 in this case) of the entry 5011 of the reconfiguration management table 5001 to “Done (ON)”. Set. Further, the spare tree usage state management flag is set to flag = OFF, so that the spare tree # 4095 can be used for additional deletion processing of other nodes.

  In the reconfiguration management table 1166, the additional node 3012 sets the reconfiguration processing flag 5013 of the tree for which the reconfiguration processing has ended to “already (ON)” and selects a tree for which the reconfiguration processing flag 5013 is OFF. Thereafter, the addition of a new node 3012 to the next tree is performed.

  Thereafter, by repeating the same process as described above, the process of adding the node 3012 to the remaining working trees # 4003 to # 4006 is executed.

  When the addition processing of the node 3012 to all the working trees # 4001 to # 4006 is completed, the adding node 3012 adds the protection tree # 4095 to each of the working trees # 4001 to # 4006 in the network. Release is notified by broadcast.

  The state of the working trees # 4001 to # 4006 to which the node 3012 has been added as described above is shown in FIG.

  In FIG. 23, the process when node # 3012 is added to the network system has been described. However, the same process as in FIG. 23 is also performed when the node constituting the network is deleted. The That is, in FIG. 23, the process when a node is deleted by describing “addition (or addition process)” as “deletion (or deletion process)” will be described.

  The effect of the third embodiment will be described. According to the third embodiment, the spanning tree can be reconfigured without stopping the network when the network configuration is changed, and the number of spanning trees that can be used in the network is limited to one half. The function of the management server 5000 shown in the first embodiment is added, together with the effect of avoiding the conventional problems and enabling the number of usable spanning trees to be expanded up to the maximum number of spanning trees −1. By providing the node to be deleted, there is an effect that it is not necessary to provide a management server for tree reconstruction.

  Note that the functions of each node and management server in the network system of each embodiment described above are not limited to hardware, and a spanning tree reconfiguration program having these functions is a computer that configures each node. It can be realized by executing on the apparatus.

  The spanning tree reconfiguration processing program is stored in a magnetic disk, a semiconductor memory, or other recording medium, loaded from the recording medium into a computer device that is a node and a management server, and controls the operation of the computer device to Each function is realized.

  Although the present invention has been described with reference to the preferred embodiments, the present invention is not necessarily limited to the above embodiments, and various modifications can be made within the scope of the technical idea.

It is a figure which shows the structural example of the Ethernet (R) frame with the conventional VLAN tag. It is a figure which shows the structural example of the Ethernet (R) frame with an extension tag of this invention. It is a figure which shows the other structural example of the Ethernet (R) frame with an extension tag of this invention. It is a figure which shows the structural example of the expansion tag storage area of this invention. It is a format figure which shows the frame structure of Configuration BPDU in this invention. It is a format figure which shows the frame structure of Topology Change Notification BPDU in this invention. It is a figure which shows the other structural example of the expansion frame in this invention. It is a block diagram which shows the structure of the network system by the 1st Embodiment of this invention. It is a block diagram which shows in detail the structure of the node which comprises the network by the 1st Embodiment of this invention. It is a figure which shows the example of the content of the forwarding table for determining an output port by using the tag of the node by the 1st Embodiment of this invention as a key. It is the block diagram which showed the structure of the reconfiguration | reconfiguration controller of the node of the 1st Embodiment of this invention in detail. It is a figure which shows the structure of the network system by 1st Embodiment. It is a figure which shows the example of a setting content of the reconstruction management table by 1st Embodiment. It is a figure which shows the tree structure of the network system by 1st Embodiment. It is a figure which shows a network structure in case a new node is added to a network. It is a sequence diagram explaining the content of the process when a new node is added to a network in 1st Embodiment. It is a figure which shows the state of the backup tree when a new node is added. It is a figure which shows the state of the working tree where the node was added in the network system shown in FIG. FIG. 10 is a sequence diagram showing details of tree reconfiguration processing by adding nodes. It is a figure explaining the setting content of the timer mode of a stable timer. It is a sequence diagram which shows the detail of the tree reconfiguration | reconstruction process by deletion of a node. It is a sequence diagram explaining the content of the process when a new node is added to a network in 2nd Embodiment. It is a sequence diagram explaining the content of the process when a new node is added to a network in 3rd Embodiment.

Explanation of symbols

# 4001 to # 4006: Working tree # 4095: Spare tree 111: Frame forwarder 112, 1163: Tag inserter 113, 1161: Tag deleter 114: Forwarding table 115: STP controller 116: Reconfiguration controller 117: Frame sorting 118: Setting interface 1162: Control frame transmission / reception unit 1164: Reconfiguration processing unit 1165: Extended reconfiguration processing unit 1166: Reconfiguration management table 1167: Stability timer 3001, 3002, 3003, 3004, 3005, 3006: Node 3012: Addition Target (or deletion target) node 5000: Management server 5011: STP-ID
5012: MAC address of root node 5013: Reconfiguration processing flag

Claims (38)

In a network system using a plurality of trees as a path for transferring a frame on a network in which a plurality of nodes are connected,
Providing at least one spare tree for use in reconfiguring the tree by adding or removing nodes from the network;
The network system, wherein the spare tree is shared in the tree reconstruction of the plurality of trees.   2. The network according to claim 1, further comprising a management server that manages a usage status of the spare tree and manages a state of the tree that is a target of tree reconstruction in addition or deletion of the node. system. A dedicated management server, and the management server has a function of managing the usage status of the spare tree;
The network system according to claim 1, wherein the node to be added or deleted has a function of managing a state of the tree that is a target of tree reconstruction in addition or deletion of the node.   The node to be added or deleted has a function of managing a usage status of the spare tree and managing a state of the tree that is a target of tree reconfiguration in addition or deletion of the node. The network system according to claim 1.   The network system according to claim 2, wherein the management server includes a management table including an address of a node serving as a root and a flag indicating whether or not a tree is reconfigured for each tree.   The node to be added or deleted includes a management table including an address of a root node and a flag indicating whether or not a tree is reconfigured for each tree. The network system described.   The management server receives an addition or deletion request from the node to be added or deleted, checks the usage status of the spare tree, and if the spare tree is usable, the management server The network system according to claim 2, wherein permission is notified to a node and a tree reconfiguration is requested to a root node of the requested tree. The root node of the tree receives an addition or deletion request from the node to be added or deleted, inquires the usage status of the spare tree to the management server, and
The network system according to claim 3, wherein the management server requests a tree reconfiguration to a root node of the tree when the spare tree is usable. The node to be added or deleted notifies the reserved use of the spare tree in the network;
If the spare tree is not in use, notify the network of the use of the spare tree and make a request for addition or deletion to the root node of the tree,
5. The network system according to claim 4, wherein a root node of the tree receives the request for addition or deletion, and executes tree reconfiguration processing. The node is
An STP controller that determines the tree to be used for forwarding;
A reconfiguration controller that performs control for tree reconfiguration by adding or deleting the node;
A forwarding table that records the forwarding output destination of frames for each destination;
10. The network system according to claim 1, further comprising: a classifier that determines an STP controller to which the frame is transferred according to the tag. The reconfiguration controller of the node is
A reconfiguration processing unit for reconfiguring the tree by a predetermined control frame;
A control frame transmission / reception unit that transmits / receives the control frame to / from another node;
The network system according to claim 10, further comprising a stability timer for detecting stability of the tree in the reconfiguration.   When the node to be added reconfigures the tree by adding the node, only the reception process of the control frame transmitted in the network is performed, so that the address of the node serving as the root is obtained for each tree from the control frame. The network system according to claim 4, wherein the network system is acquired.   The network system according to any one of claims 1 to 12, wherein the tree is a spanning tree. A tree reconfiguration processing method for a network system that uses a plurality of trees as a path for transferring a frame on a network connecting a plurality of nodes,
Providing at least one spare tree to be used when reconfiguring the tree by adding or deleting nodes to the network, and sharing the spare tree in the tree reconfiguration of the plurality of trees; A tree reconstruction processing method characterized by the above.   15. The management server provided in the network manages the usage status of the spare tree, and manages the state of the tree that is a target of tree reconfiguration in addition or deletion of the node. The tree reconstruction processing method described in 1. A management server provided in the network manages the usage status of the spare tree;
The tree reconfiguration processing method according to claim 14, wherein the node to be added or deleted manages a state of the tree that is a target of tree reconfiguration in addition or deletion of the node.   The node added or deleted manages the usage status of the spare tree, and manages the state of the tree that is a target of tree reconfiguration in addition or deletion of the node. 14. The tree reconfiguration processing method according to 14.   16. The tree reconfiguration processing method according to claim 15, wherein the management server includes a management table including an address of a node serving as a root and a flag indicating the presence / absence of tree reconfiguration for each tree.   The node to be added or deleted includes a management table including an address of a node serving as a root and a flag indicating whether or not a tree is reconfigured for each tree. The tree reconstruction processing method described.   When the management server receives an addition or deletion request from the node to be added or deleted, checks the usage status of the spare tree, and if the spare tree is usable, the management server is subject to addition or deletion The tree reconfiguration processing method according to claim 15, wherein the tree reconfiguration processing method is configured such that permission is notified to a node and a tree reconfiguration is requested to a root node of the requested tree. The root node of the tree receives an addition or deletion request from the node to be added or deleted, inquires the usage status of the spare tree to the management server, and
The tree reconfiguration processing method according to claim 16, wherein the management server requests a tree reconfiguration to a root node of the tree when the spare tree is usable. The node to be added or deleted notifies the reserved use of the spare tree in the network;
If the spare tree is not in use, notify the network of the use of the spare tree and make a request for addition or deletion to the root node of the tree,
18. The tree reconfiguration processing method according to claim 17, wherein a root node of the tree receives the request for addition or deletion, and executes a tree reconfiguration process.   When the node to be added reconfigures the tree by adding the node, only the reception process of the control frame transmitted in the network is performed, so that the address of the node serving as the root is obtained for each tree from the control frame. The tree reconstruction processing method according to claim 17, wherein the tree reconstruction processing method is obtained. A node of a network system that uses a plurality of trees as a path for transferring a frame on a network connecting a plurality of nodes,
A function for sharing at least one spare tree used in reconfiguring the tree by adding or deleting nodes in the network in the tree reconfiguration of the plurality of trees; Feature node.   The node to be added or deleted has a function of managing a usage status of the spare tree and managing a state of the tree that is a target of tree reconfiguration in addition or deletion of the node. The node of claim 24.   26. The node according to claim 25, wherein the node to be added or deleted comprises a management table including an address of a node serving as a root and a flag indicating whether or not a tree is reconfigured for each tree. The node to be added or deleted notifies the reserved use of the spare tree in the network;
If the spare tree is not in use, notify the network of the use of the spare tree and make a request for addition or deletion to the root node of the tree,
25. The node according to claim 24, wherein a root node of the tree receives the request for addition or deletion, and executes a tree reconfiguration process. An STP controller that determines the tree to be used for forwarding;
A reconfiguration controller that performs control for tree reconfiguration by adding or deleting the node;
A forwarding table that records the forwarding output destination of frames for each destination;
The node according to any one of claims 24 to 27, further comprising: a classifier that determines an STP controller to which the frame is transferred according to the tag. The reconfiguration controller
A reconfiguration processing unit for reconfiguring the tree by a predetermined control frame;
A control frame transmission / reception unit that transmits / receives the control frame to / from another node;
29. The node of claim 28, comprising a stability timer for detecting tree stability in reconfiguration. In a network system that uses a plurality of trees as a path for transferring a frame on a network connecting a plurality of nodes, a tree reconfiguration processing program for executing a tree reconfiguration process executed on a computer device,
Said computer device,
A function of causing at least one spare tree used when reconfiguring the tree by adding or deleting a node to the network to be shared in the tree reconfiguration of the plurality of trees. Tree reconstruction processing program.   The computer device constituting the management server provided in the network functions as means for managing the use status of the spare tree and managing the status of the tree that is the target of tree reconfiguration in addition and deletion of the node. The tree reconstruction processing program according to claim 30, wherein the tree reconstruction processing program is executed. Causing a computer device constituting a management server provided in the network to function as a means for managing the usage status of the spare tree;
31. The computer device constituting the node to be added or deleted is caused to function as means for managing the state of the tree that is a target of tree reconstruction in addition or deletion of the node. Tree reconstruction program.   The computer device constituting the node to be added or deleted as means for managing the usage status of the spare tree and managing the state of the tree to be reconfigured in the addition or deletion of the node The tree reconstruction processing program according to claim 30, wherein the tree reconstruction processing program is made to function.   32. The tree reconfiguration processing program according to claim 31, wherein the management server includes a management table including a node address serving as a root and a flag indicating the presence or absence of tree reconfiguration for each tree.   The node to be added or deleted comprises a management table including an address of a node serving as a root and a flag indicating whether or not a tree is reconfigured for each tree. The tree reconstruction processing program described.   The management server receives an addition or deletion request from the node to be added or deleted, checks the usage status of the spare tree, and if the spare tree is usable, the addition or deletion target 32. The tree reconfiguration processing program according to claim 31, wherein the tree reconfiguration processing program is configured to execute a function of requesting tree reconfiguration to a root node of the requested tree while notifying the node of permission. In response to an addition or deletion request from the node to be added or deleted to the root node of the tree, inquiring about the usage status of the spare tree to the management server,
The tree reconfiguration process according to claim 32, wherein the management server causes a function of requesting a tree reconfiguration to a root node of the tree when the spare tree is usable. program. The node to be added or deleted notifies the reserved use of the spare tree in the network;
If the spare tree is not in use, notify the network of the use of the spare tree and make a request for addition or deletion to the root node of the tree,
The tree reconfiguration processing program according to claim 33, wherein a root node of the tree receives the request for addition or deletion, and executes a function of executing a tree reconfiguration process.

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