JP2006081057A - Layer 2 switch apparatus, layer 3 switch apparatus, switching method and program therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that a CPU use rate of a terminal is increased (overload is caused) since also a useless broadcast packet is received in a terminal connected to one port of a switch when a plurality of VLANs are bundled and set to the port. <P>SOLUTION: A management method is characterized in that transmitting side management of a VLAN in a communication repeater of a LAN is performed not in a conventional link-up timing but in a timing of first packet reception, and the management method is also characterized in that a packet is not positively transmitted from a switch side until receiving a packet from a terminal side. A plurality of VLANs are set to a terminal side physical port of the communication repeater, receiving state management of a port inside the communication repeater is not changed but kept as conventional and transmitting state management of the port in the communication repeater is changed. Broadcast main management all over the network is automatically performed on the switch side, thereby efficiently constructing the network. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to transmission management in a LAN switch, and in particular, a layer 2 switch device and a layer 3 switch using passive VLAN ports that do not transmit to unnecessary ports during operation in which a plurality of VLANs are overlapped and set in one port. The present invention relates to an apparatus, a switching method, and a program thereof.

  In a company, a network (intranet) is always used because of its convenience. In addition, it is natural to set access restrictions between departments within an intranet. In general, in order to cope with network security, access is often restricted by dividing a subnet (upper part of an IP address) for each department and describing rules in units of subnets. On the other hand, even when a mobile terminal such as a laptop computer is moved from a place where it is usually used, a technology that enables the same communication as usual is desired.

  Recently, DHCP (Dynamic Host Configuration Protocol) technology has created an environment where users can start communication without worrying about troublesome IP address settings. However, since the IP address assigned by DHCP at the location after moving is different from the environment where the subnet part is normally used, there are access restrictions different from usual, and there is a problem that there is a situation where the information you want to use cannot be accessed immediately. there were.

  As a basic technology in a LAN (Local Area Network) switch, there is a technology called VLAN (Virtual LAN) that divides a broadcast domain. Furthermore, there is a technology called tag VLAN in which a plurality of VLANs are stacked on one port. The tag VLAN is a technique for embedding a tag for identifying VLAN information in a packet header (Ethernet (registered trademark) header) and transmitting the packet. As a conventional general use method, between expensive switches in the backbone Often used on high-bandwidth ports. Tag VLAN is a technique for superimposing the broadcast domain instead of dividing it. Recently, an inexpensive terminal (such as an IP phone) on which a tag VLAN is mounted has appeared.

  For example, Patent Document 1 describes a switch and a VLAN system using the switch, which accepts a reservation for movement of a terminal from a movement source terminal at a movement destination switch.

Even when a certain terminal is moved and connected to another switch by applying the setting to stack multiple tag VLANs that were used in limited ports on the backbone side to the terminal side port of the switch, Then, you can use it as usual. Specifically, the operation is as follows.
1. Set up VLANs for all departments that you want to be able to move terminals over to the terminal side ports on each floor (switch)
2. 2. Start DHCP server for each VLAN. The tag attached to the packet sent by the terminal is fixed on the terminal side (terminal)
In the above operation, even if the terminal is moved and connected to a switch on another floor, 1. The DHCP address request from the terminal is delivered to the appropriate VLAN DHCP server by the tag attached to the packet issued by the terminal.
2. The IP address of the same subnet as usual is issued.

JP 2002-64523 (page 3-6, FIG. 1)

  However, since the broadcast domain is simply overlapped in the above-described method, a packet of a different VLAN actually reaches the terminal side excessively. In the reception process on the terminal side, packets of different VLANs (tags) are discarded at the Layer 2 level. This discarding operation sometimes becomes a problem in a weak terminal. In addition, since the number of copies of broadcast packets to other ports is large on the switch side, the processing capacity may be exceeded.

In a network environment constructed with a conventional communication relay device (LAN switch), it has been difficult to satisfy the following three conditions simultaneously.
-Use the same VLAN (IP subnet) in the same department, and different VLANs in different departments.
・ When moving between floors when holding a meeting between multiple departments, the same IP subnet address (VLAN) as usual is used even if the notebook PC is connected to a communication relay device that is different from the communication relay device normally used. What you can do.
-The terminal must not receive (useless) broadcasts from different IP subnets.

  Although it was possible in the past to satisfy the first and second conditions among the three conditions, since the third condition could not be satisfied, the terminal received even a useless broadcast packet, and the terminal CPU usage rate increase (overload).

  The present invention applies the third condition solving means to a switch (communication relay device) to thereby solve a problem on the switch side / terminal side due to useless broadcast transmission / reception, and a layer 2 switch device using a passive VLAN port. , A layer 3 switching device, a switching method and a program thereof are proposed.

  A first layer 2 switching device according to the present invention is a layer 2 switching device having a plurality of ports connecting terminals and a switching means for tag VLAN packets from the terminals. Setting of the tag VLAN identifier of the packet, setting of a transmission permission / non-permission attribute indicating whether or not to transmit to the set port upon reception of a tag VLAN packet having the same tag VLAN identifier with respect to the set tag VLAN identifier, VLAN setting management means for storing a tag, and a broadcast domain that changes a transmission permission attribute of the tag VLAN identifier to transmission permission when a tag VLAN packet that matches the tag VLAN identifier is received at a port having a setting that the tag VLAN identifier cannot transmit Management means, and the broadcaster The domain management unit controls the transmission / reception packet according to the information stored in the VLAN setting management unit, and when the transmission permission attribute of the tag VLAN of the transmission destination port of the received tag VLAN packet is transmittable, transmits to the port If the transmission is impossible, transmission to the port is not performed.

  In the second layer 2 switching device of the present invention, in the first layer 2 switching device, the broadcast domain management means sets the same tag VLAN identifier as the tag VLAN packet when receiving the tag VLAN packet. When the transmission permission / prohibition attribute of the tag VLAN identifier of the port cannot transmit, the copy operation of the tag VLAN packet to the port is not performed.

  According to a third layer 2 switching device of the present invention, in the first layer 2 switching device, the layer 2 switching device further includes a port link state management unit, and the port link state management unit includes a link down When a detected port is detected, the transmission permission attribute of the tag VLAN identifier set for the port is changed to transmission disabled.

  The layer 3 switching device of the present invention is a layer 3 switching device having a plurality of ports connecting the layer 2 switching device and a switching means for tag VLAN packets transmitted from the layer 2 switching device. Setting of tag VLAN identifier of target tag VLAN packet and transmission / non-transmission of whether or not to transmit to the set port upon reception of tag VLAN packet having the same tag VLAN identifier with respect to the set tag VLAN identifier VLAN setting management means for storing attribute settings, and transmission of the tag VLAN identifier transmission permission attribute when a tag VLAN packet that matches the tag VLAN identifier is received at a port having a tag VLAN identifier non-transmittable setting Broadcast domain management to change to The broadcast domain management means controls the transmission / reception packet according to the information stored in the VLAN setting management means, and the transmission permission attribute of the tag VLAN of the destination port of the received tag VLAN packet can be transmitted. In this case, transmission is performed to the port. When transmission is impossible, transmission is not performed to the port.

  According to the first switching method of the present invention, the VLAN setting management means has a tag VLAN identifier of a tag VLAN packet to be transmitted / received with respect to the port of the switch device having a plurality of ports and a tag VLAN packet switching means. Storing the setting and setting of a transmission permission / non-permission attribute indicating whether or not to transmit to the set port upon reception of a tag VLAN packet having the same tag VLAN identifier with respect to the set tag VLAN identifier; When the broadcast domain management means of the switch device receives a tag VLAN packet that matches the tag VLAN identifier at a port having a tag VLAN identifier set to be non-transmittable, it changes the transmission permission attribute of the tag VLAN identifier to be transmittable. And the broadcast domain administrator The stage controls the transmission / reception packet of the switch device according to the information stored in the VLAN setting management means, and if the transmission availability attribute of the tag VLAN of the transmission destination port of the received tag VLAN packet is transmittable, A step of performing transmission and not transmitting to the port when transmission is not possible.

  According to the second switching method of the present invention, the VLAN setting management means sends the tag VLAN identifier of the tag VLAN packet to be transmitted / received to / from the port of the switch device having a plurality of ports and the tag VLAN packet switching means. Storing the setting and setting of a transmission permission / non-permission attribute indicating whether or not to transmit to the set port upon reception of a tag VLAN packet having the same tag VLAN identifier with respect to the set tag VLAN identifier; When the broadcast domain management means receives a tag VLAN packet that matches the tag VLAN identifier at a port whose tag VLAN identifier is set to disable transmission, the broadcast domain management means changes the transmission permission attribute of the tag VLAN identifier to transmission enabled; The domain management means includes the VLAN The transmission / reception packet of the switch device is controlled according to the information stored in the setting management means. When the transmission availability attribute of the tag VLAN of the transmission destination port of the received tag VLAN packet is transmittable, the transmission is performed to the port. If not possible, a step of not transmitting to the port; and a step of changing the transmission permission attribute of the tag VLAN identifier set to the port to non-transmittable when the port link state management unit detects a port that has been linked down. , Including.

  According to a first program of the present invention, a VLAN setting management unit includes a tag VLAN of a tag VLAN packet to be transmitted / received with respect to the port of the switch device having a plurality of ports and a tag VLAN packet switching unit. Storing an identifier setting and a transmission permission / non-permission attribute setting indicating whether or not to transmit to the set port when receiving a tag VLAN packet having the same tag VLAN identifier with respect to the set tag VLAN identifier. And when the broadcast domain management means receives a tag VLAN packet that matches the tag VLAN identifier at a port having a tag VLAN identifier not transmittable, and changes the transmission enable / disable attribute of the tag VLAN identifier to transmit enabled, Broadcast domain management means The transmission / reception packet of the switch device is controlled in accordance with the information stored in the VLAN setting management means. If the transmission permission attribute of the tag VLAN of the transmission destination port of the received tag VLAN packet is transmittable, the transmission is performed to the port. If the transmission is impossible, the step of not transmitting to the port is executed.

  According to a second program of the present invention, a VLAN setting management unit includes a tag VLAN of a tag VLAN packet to be transmitted / received with respect to the port of the switch device having a plurality of ports and a tag VLAN packet switching unit. The setting of the identifier and the setting of the transmission permission / non-permission attribute indicating whether or not to transmit to the set port when receiving the tag VLAN packet having the same tag VLAN identifier with respect to the set tag VLAN identifier are received and stored. And when the broadcast domain management means receives a tag VLAN packet that matches the tag VLAN identifier at a port having a tag VLAN identifier set to disable transmission, and changes the transmission permission attribute of the tag VLAN identifier to transmission enabled. The broadcast domain The control unit controls the transmission / reception packet of the switch device according to the information stored in the VLAN setting management unit, and when the transmission enable / disable attribute of the tag VLAN of the destination port of the received tag VLAN packet is transmittable, If the port link state management means detects a port that has been linked down, it transmits a transmission permission attribute of the tag VLAN identifier set for the port. The step of changing to impossible is executed.

The following effects are obtained.
(1) Unnecessary VLAN data is not transmitted to the terminal side connected to the switch port by broadcast domain division, so that the receiving load on the terminal side can be reduced.
(2) On the switch side, an unnecessary copy operation to the port is not necessary, and the transmission load can be reduced.

  Next, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 illustrates the configuration of the present embodiment. The communication relay device 10 (LAN switch) includes a VLAN setting management unit 11, a port link state management unit 12, and a broadcast domain management unit 15. Each means is stored in the ROM of the communication relay device 10 and performs a program operation using the CPU of the communication relay device 10 and a main memory (RAM).

  Furthermore, the broadcast domain management unit 15 (multicast group management) includes an active VLAN port management unit 151 and a passive VLAN port management unit 152 that executes a passive VLAN port transmission management function.

  FIG. 2 shows a configuration comprising a layer 3 switch (hereinafter referred to as an L3 switch), a plurality of layer 2 switches (hereinafter referred to as L2 switches) connected to the L3 switch, and a terminal connected to a port of each L2 switch. It represents that each terminal belongs to a certain VLAN (Virtual LAN). As illustrated in FIG. 2, a passive VLAN port is set to the port of the L2 switch directly connected to the terminal. In FIG. 2, the port indicated by “◯” is a port where a passive VLAN port is set, and the port indicated by “x” is a port in which a conventional VLAN is multiplexed (hereinafter referred to as an active VLAN port). .

  A passive VLAN port is defined for a set of ports and VLANs set on the ports. When the passive VLAN port is set, transmission to the port is not performed even if there is a transmission request for the same VLAN from another port. When the first VLAN packet is received from the terminal connected to the defined port of the passive VLAN port, it is determined whether or not the passive VLAN is set. According to the VLAN of the received packet, “the setting of the VLAN is set from the passive VLAN. Change to the “active VLAN” state and transmit the first packet received.

  Next, the operation of the best mode for carrying out the present invention will be described with reference to the drawing including the flowchart of FIG.

  FIG. 3 illustrates the communication relay device (L2 switch) 10 in FIG. 2 in detail.

  The user performs initial setting for each port of the communication relay device 10 using a personal computer (not shown) or the like. When receiving the initial setting information, the VLAN setting management means 11 stores it in the nonvolatile ROM of the communication relay device 10. For example, assume that the following setting is performed as an example of the initial setting.

  A conventional active VLAN in which VLAN 1 to VLAN 3 are overlapped is set to port 1 of the communication relay device 10 (O in each column of “Send” in the port 1 box represents the active VLAN).

  In the following description, it is assumed that only one terminal is connected to the port on the terminal side of the communication relay device 10.

Ports 2 to 5 are overlapped with VLAN 1 to VLAN 3 to set a passive VLAN port for each VLAN (step S1). To express). (Note that ◯ and X are explanatory, and are stored in the ROM by turning the bit off, on, etc., respectively.)
As an initial state, the passive VLAN port is “x” indicating that the L2 switch does not transmit the VLAN packet to the port.

  Since each port accepts reception of a packet, VLAN reception control is turned on (step S2).

  It is assumed that the operation of the communication relay device 10 is started in this setting state. The broadcast domain management unit 15 reads the initial setting information stored in the ROM by the VLAN setting management unit 11 and temporarily stores it in the main memory (RAM). Thereafter, reference and update processing are executed on the temporarily stored information.

The port link state management means 12 confirms whether or not each port of the communication relay device 10 has been linked up (step S3).
Assume that ports 1 to 5 are in a link-up state. When receiving a packet from the port 1 terminal, the broadcast domain management means 15 refers to the information temporarily stored in the main storage memory to check whether the destination port has a passive VLAN setting (step S4). Does not transfer to any port for setting the passive VLAN is in each VLAN Port 2 Port 5 (step S5).

  Next, in FIG. 4, when the communication relay device 10 receives a packet of VLAN 1 from port 2, for example, the broadcast domain management means 15 determines the VLAN setting state of port 2 (step S6). In this case, since the packet is a tag of VLAN1, the packet is transmitted to port 1 participating in VLAN1, and the VLAN1 transmission management state of port 2 is changed to “◯” indicating that transmission is possible, and the passive VLAN is changed to the active VLAN state (step) S7).

  Next, as shown in FIG. 5, when the communication relay device 10 receives a VLAN1 packet from port 1, transmission to port 2 is executed because the setting state of VLAN1 of port 2 is transmittable. Since the setting state of VLAN 1 for ports 3 to 5 continues to be “x”, no transmission is performed.

  Next, in FIG. 5, when a packet is received from the VLAN 3 of the port 4, it is transmitted to the port 1 participating in the VLAN 3, and the VLAN 3 transmission management state of the port 4 is changed to “◯” indicating that transmission is possible. In this way, the VLAN state of each port changes from the initial setting of the passive VLAN to the active VLAN.

  When the contents described with reference to FIGS. 3 to 5 are applied to actual operation, a DHCP server belonging to each VLAN is connected to VLAN 1 to VLAN 3 of port 1. When each terminal connected to each VLAN of ports 2 to 5 starts up and transmits an IP address setting request packet to the DHCP server, the passive VLAN port state changes to the active VLAN port state when the request packet is received. Therefore, the requesting terminal can receive the IP address assigned by the DHCP server. In this case, ports 2 to 5 that do not request IP address assignment remain in the passive VLAN port state, and therefore, there is an effect that unnecessary transmission to the port is not performed.

  FIG. 8 shows a stable state after further receiving a packet from the terminal in a state where all the terminal side ports (port 2 to port 5) are linked up. The transmission state of the terminal side port is “◯” for only one VLAN. In this state, when a packet of VLAN 1 is received from port 1, it is transferred only to port 2 and port 3. Terminals ahead of port 4 and port 5 do not receive any unnecessary VLAN 1 packets. In addition, the number of copies required in the communication relay device 10 is reduced, and the load on the communication relay device 10 itself is reduced.

  Finally, as shown in FIG. 6, when the port 2 is linked down (step S8), the port link state management means 12 changes the transmission state of all VLANs set in the port 2 to “x”, and the passive VLAN port A state is set (step S9). For the process of “x”, only the link down trigger is sufficient, and there is an effect that the mounting cost is low and the processing cost of the switch can be kept low.

  Next, a second embodiment of the present invention will be described with reference to FIG.

  FIG. 9 includes three L2 switches, terminals connected to the respective ports, and a layer 3 switch (L3 switch) that bundles the L2 switches. In FIG. 9, the port assigned “◯” is a passive VLAN port, and the port assigned “×” is a conventional active VLAN port.

  In this embodiment, the contents of the L2 switch described in the first embodiment are applied to the layer 3 switch, and the configuration and the function of the L2 switch described in FIG. 1 remain unchanged in the L3 switch in the second embodiment. Is also applicable.

  In the first embodiment, as illustrated in FIG. 2, the passive VLAN port setting is performed only for the port accommodating the terminal. However, in the second embodiment, the definition of the passive VLAN port is relaxed and expanded not to “only one transmission side VLAN” but “allow multiple transmission side VLANs”. By expanding in this way, it is possible to use the expanded contents in the L3 switch in FIG.

  Even after expansion, the uplink side of the L2 switch in FIG. 9 should not be set as a passive VLAN port. The setting state for each port of the L3 switch in FIG. 9 is as shown in FIG. 10 reflecting the definition of the VLAN of the terminal connected to each port of each L2 switch.

  For example, when a transmission request is transmitted from a terminal belonging to VLAN 1 connected to port 1 of L2 switch 1, it is received at port 1 of L3 switch via L2 switch 1. In the initial setting of port 1 of the L3 switch, VLAN 1 is set as a passive VLAN port, but this reception is changed to an active VLAN port. Similarly, the setting of the passive VLAN port set in the VLAN 2 of the L3 switch port 1 changes to the active VLAN port in response to a transmission request from the terminal of the VLAN 2 under the port 3 of the L2 switch 1. This is shown in the table relating to port 1 of the L3 switch in FIG.

  In FIG. 10, when there is a transmission request from a terminal belonging to VLAN 2 of L2 switch 2, L2 switch is set as a passive VLAN port state in the setting of port 3 of L3 switch. 3 is not performed. As described above, copy processing is reduced even in the L3 switch.

  However, there are two points that need attention.

  As the first point, since the transmission state is returned from “O” to “X” only when the link is down, if the terminal movement continues under the L2 switch, the transmission state of each port in the L3 switch is “ The VLAN indicated by “あ る” may eventually become all VLANs (VLAN1 to VLAN5). This point can be avoided by linking with aging (no communication monitoring) in the L3 switch.

  As the second point, there is a case where a redundant configuration based on STP (Spanning Tree Protocol) is considered by further developing from the configuration shown in FIG. If all transmissions to the passive VLAN port are temporarily stopped, the STP protocol is not transmitted, and the redundant configuration does not function as expected. It is better to control STP protocol packets to be transmitted even in the initial state of the passive VLAN port. Implementation of such transmission control itself is easy, and problems are avoided.

  The present invention can be applied to L2 switch products and L3 switch products to improve performance.

It is a block diagram explaining the structure of the 1st Example of this invention. It is explanatory drawing of the structural example explaining the operation | movement of the 1st Example of this invention. It is explanatory drawing of operation | movement of the 1st Example of this invention. It is explanatory drawing of operation | movement of the 1st Example of this invention. It is explanatory drawing of operation | movement of the 1st Example of this invention. It is explanatory drawing of operation | movement of the 1st Example of this invention. It is a flowchart explaining the operation | movement of the 1st Example of this invention. It is explanatory drawing of operation | movement of the 1st Example of this invention. It is explanatory drawing of the structural example explaining the operation | movement of the 2nd Example of this invention. It is explanatory drawing of operation | movement of the 2nd Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Communication relay apparatus 11 VLAN setting management means 12 Port link state management means 15 Broadcast domain management means 151 Active VLAN port management means 152 Passive VLAN port management means

Claims (8)

In a layer 2 switching device having a plurality of ports connecting terminals and a switching means for tag VLAN packets from the terminals,
For the port, the tag VLAN identifier of the tag VLAN packet to be transmitted / received is set, and the tag VLAN packet having the same tag VLAN identifier with respect to the set tag VLAN identifier is received and transmitted to the set port. VLAN setting management means for storing a transmission permission / inhibition attribute setting indicating whether or not to perform,
Broadcast domain management means for changing a transmission permission attribute of the tag VLAN identifier to transmission permission when a tag VLAN packet that matches the tag VLAN identifier is received at a port having a tag VLAN identifier setting that transmission is disabled;
The broadcast domain management means controls the transmission / reception packet according to the information stored in the VLAN setting management means. If the transmission availability attribute of the tag VLAN of the destination port of the received tag VLAN packet is transmittable, the broadcast domain management means A layer 2 switch device that performs transmission and does not transmit to the port when transmission is impossible. The broadcast domain management means, when receiving the tag VLAN packet, if the transmission enable / disable attribute of the tag VLAN identifier of the port in which the same tag VLAN identifier as the tag VLAN packet is set cannot be transmitted, the tag VLAN packet to the port 2. The layer 2 switching apparatus according to claim 1, wherein no copy operation is performed. The layer 2 switch device further includes a port link state management means,
2. The layer 2 switch device according to claim 1, wherein when the port link state management unit detects a port that is linked down, the transmission / non-transmission attribute of the tag VLAN identifier set to the port is changed to non-transmission. In a layer 3 switching device having a plurality of ports connecting the layer 2 switching device and a switching means for tag VLAN packets transmitted from the layer 2 switching device,
Setting of the tag VLAN identifier of the tag VLAN packet to be transmitted / received to the port, and transmission to the set port upon reception of a tag VLAN packet having the same tag VLAN identifier with respect to the set tag VLAN identifier VLAN setting management means for storing a transmission permission / inhibition attribute setting indicating whether or not to perform,
Broadcast domain management means for changing a transmission permission attribute of the tag VLAN identifier to transmission enabled when a tag VLAN packet that matches the tag VLAN identifier is received at a port having a tag VLAN identifier setting that transmission is disabled;
The broadcast domain management unit controls the transmission / reception packet according to the information stored in the VLAN setting management unit, and when the transmission availability attribute of the tag VLAN of the transmission destination port of the received tag VLAN packet is transmittable, to the port A layer 3 switching device that performs transmission and does not transmit to the port when transmission is impossible. The VLAN setting management means sets the tag VLAN identifier of the tag VLAN packet to be transmitted / received and the set tag VLAN identifier for the port of the switch device having a plurality of ports and tag VLAN packet switching means. Storing a transmission permission / non-permission attribute setting indicating whether or not to transmit to the set port when receiving a tag VLAN packet having the same tag VLAN identifier;
When the broadcast domain management means of the switch device receives a tag VLAN packet that matches the tag VLAN identifier at a port having a tag VLAN identifier set to be non-transmittable, it changes the transmission permission attribute of the tag VLAN identifier to be transmittable. When,
When the broadcast domain management unit controls the transmission / reception packet of the switch device according to the information stored in the VLAN setting management unit, and the transmission enable / disable attribute of the tag VLAN of the destination port of the received tag VLAN packet is transmittable , When transmitting to the port, and when transmission is not possible, not transmitting to the port;
A switch method comprising: The VLAN setting management means sets the tag VLAN identifier of the tag VLAN packet to be transmitted / received and the set tag VLAN identifier for the port of the switch device having a plurality of ports and tag VLAN packet switching means. Storing a transmission permission attribute indicating whether or not to transmit to the set port when receiving a tag VLAN packet having the same tag VLAN identifier;
When the broadcast domain management unit receives a tag VLAN packet that matches the tag VLAN identifier at a port having a setting that the tag VLAN identifier cannot transmit, the transmission domain attribute of the tag VLAN identifier is changed to transmittable;
When the broadcast domain management unit controls the transmission / reception packet of the switch device according to the information stored in the VLAN setting management unit, and the transmission enable / disable attribute of the tag VLAN of the destination port of the received tag VLAN packet is transmittable , When transmitting to the port, and when transmission is not possible, not transmitting to the port;
When the port link state management means detects a port that has been linked down, a step of changing the transmission enable / disable attribute of the tag VLAN identifier set to the port to disable transmission;
A switch method comprising: On the computer,
The VLAN setting management means sets the tag VLAN identifier of the tag VLAN packet to be transmitted / received and the set tag VLAN identifier for the port of the switch device having a plurality of ports and tag VLAN packet switching means. Storing a transmission permission / non-permission attribute setting indicating whether or not to transmit to the set port when receiving a tag VLAN packet having the same tag VLAN identifier;
When the broadcast domain management means receives a tag VLAN packet that matches the tag VLAN identifier at a port whose tag VLAN identifier is set to be non-transmittable, the broadcast domain management means changes the transmitability attribute of the tag VLAN identifier to transmittable;
When the broadcast domain management unit controls the transmission / reception packet of the switch device according to the information stored in the VLAN setting management unit, and the transmission enable / disable attribute of the tag VLAN of the destination port of the received tag VLAN packet is transmittable , When transmitting to the port, and when transmission is not possible, not transmitting to the port;
A program characterized by having executed. On the computer,
The VLAN setting management means sets the tag VLAN identifier of the tag VLAN packet to be transmitted / received and the set tag VLAN identifier for the port of the switch device having a plurality of ports and tag VLAN packet switching means. Receiving and storing a transmission permission / non-permission attribute setting indicating whether or not to transmit to the set port upon reception of a tag VLAN packet having the same tag VLAN identifier;
When the broadcast domain management means receives a tag VLAN packet that matches the tag VLAN identifier at a port whose tag VLAN identifier is set to be non-transmittable, the broadcast domain management means changes the transmitability attribute of the tag VLAN identifier to transmittable;
When the broadcast domain management unit controls the transmission / reception packet of the switch device according to the information stored in the VLAN setting management unit, and the transmission enable / disable attribute of the tag VLAN of the destination port of the received tag VLAN packet is transmittable , When transmitting to the port, and when transmission is not possible, not transmitting to the port;
When the port link state management means detects a port that has been linked down, a step of changing the transmission availability attribute of the tag VLAN identifier set to the port to transmission impossible;
A program characterized by having executed.

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