JP4839334B2 - Redundant protocol coexistence system and transfer device - Google Patents

Description

  The present invention relates to a redundant protocol coexistence system and a transfer device, and more particularly to a redundant protocol coexistence system and a transfer device in which STP (Spanning Tree Protocol, Spanning Tree Protocol) and VRRP (Virtual Router Redundancy Protocol, Virtual Router Redundancy Protocol) coexist.

  For example, STP is used as a protocol for preventing loops when layer 2 network redundancy is performed. In STP, each device exchanges protocol packets including parameters between adjacent network devices that implement the protocol. In the network device that has received the packet, the communication packet is blocked by the network interface between the network devices operating the protocol by an algorithm defined by the protocol, and a tree-structure topology is formed in the layer 2 network. This realizes loop prevention in the layer 2 network. The details of STP are defined in, for example, IEEE 802.1D.

  As a protocol used for redundancy of the layer 3 network, for example, there is VRRP (for example, see Non-Patent Document 1). VRRP realizes redundancy by using two network devices to virtually recognize adjacent devices as one network device (hereinafter referred to as a virtual router). Of the two, the side that communicates with neighboring devices is the master router, and the other is the backup router. In the virtual router, both the master router and the backup router are different from the IP address set for the network interface in operation and the MAC address fixed to the network interface by the network equipment vendor (hereinafter referred to as the physical MAC address). The common IP address and MAC address are used. These common IP address and MAC address are hereinafter referred to as a virtual IP address and a virtual MAC address, respectively. The virtual router communicates with peripheral devices using this virtual IP address and virtual MAC address. When a failure occurs in the master router and communication cannot be continued, the backup router switches to the master router and performs communication, allowing communication to continue without detecting a failure in an adjacent network device. It is. In VRRP, a backup router confirms the existence of a master router upon arrival of a protocol packet (hereinafter referred to as VRRP advertisement) transmitted from a master router between two network devices that operate the protocol.

R. Hinden, “Virtual Router Redundancy Protocol”, RFC 3768, April 2004.

  When a topology change of the STP occurs in a network that realizes redundancy of the layer 2 network by constructing a plurality of trees by STP like a wide area Ethernet network, the topology is reconfigured. In the transitional state until the topology change converges, the network interface of the network device that is reconstructing the topology repeats blocking (hereinafter referred to as a blocking state) and passing (hereinafter referred to as a forwarding state) of communication packets. When a multi-layer switch located at the edge of such a network realizes redundancy of a layer 3 network located downstream by VRRP, if a topology change occurs in the upstream layer 2 network, a virtual router based on VRRP The network interface of the backup router belonging to may transition to the blocking state. At this time, the backup router cannot receive the VRRP advertisement transmitted from the master router belonging to the virtual router. As a result, the backup router may mistakenly detect a failure of the master router, and the backup router may become the master router.

  In addition, the backup router that erroneously detects the failure of the master router becomes the master router and starts to transmit the VRRP advertisement. The neighboring device that has received the VRRP advertisement learns the virtual MAC address set as the transmission source MAC address in the MAC sublayer header of the VRRP advertisement, and transfers to the network interface that has received the VRRP advertisement. Master router) is recognized. However, while the STP topology is being reconstructed, the network interface of the transfer destination multilayer switch may be in a blocking state. In addition, another switch or the like further transferred from the transfer destination multilayer switch may be in a blocking state. In such a case, if a packet is transmitted to the transfer destination learned earlier, the network interface such as the multilayer switch is in a blocking state, and therefore upstream communication may be interrupted.

  As one of the problems of the present invention, VRRP advertisement from a master router in a multilayer switch that is a backup router of a virtual router as described above when a network interface is in a blocking state due to a transient state of STP topology change. May not be received. In that case, a fault in the master router is erroneously detected, and the multilayer switch that erroneously becomes the master router transmits a VRRP advertisement. For example, when the network interface of the multi-layer switch that mistakenly becomes the master router is in the forwarding state again, a VRRP advertisement is transmitted on the network. The neighboring switches that have received the VRRP advertisement register in the MAC address table of their own devices that the virtual MAC address owner is a layer 3 switch that has become the master router by mistake. For this reason, when a packet addressed to the virtual MAC address is received, a relay packet is transmitted to the multilayer switch that erroneously becomes the master router. However, when the topology change of the STP has not converged and the transfer destination receiving network interface transitions to the blocking state, the relay may be interrupted.

  As another issue, when a topology change occurs in the STP topology of the layer 2 network to which the two multilayer switches constituting the VRRP virtual router belong, and the layer 2 network becomes a loop configuration in the transient state, When the VRRP advertisement loops in the network, the network bandwidth and the CPU resource of the switch that has received the VRRP advertisement may be consumed.

In view of the above, an object of the present invention is to prevent erroneous detection of a master router down in a backup router. Another object of the present invention is to make it possible for the backup router to receive the VRRP advertisement transmitted from the master router in the transient state when the topology of the STP is changed, regardless of the state of the STP. To do.
Another object of the present invention is to prevent a packet loop by discarding a VRRP advertisement transmitted from the own apparatus even when the layer 2 network has a loop configuration. An object of the present invention is to prevent switch CPU resource consumption by preventing packet loops.

  An object of the present invention is to provide a system that can be installed without changing the protocol in a system that uses a multi-vendor protocol and performs redundancy control using STP and VRRP.

As means for solving these problems, for example, the following means are used.
(Means 1)
The physical MAC address information of the master router that transmits the VRRP advertisement is added to the VRRP advertisement. Conventionally, in a multilayer switch constituting a virtual router based on VRRP, the physical MAC address is not set in the MAC sublayer header at the time of packet transmission, and the virtual MAC address is set in the MAC sublayer header. In the present invention, the transmission source of the VRRP advertisement is determined by the received multilayer switch by assigning a physical MAC address that has not been used conventionally to the VRRP advertisement.

(Means 2)
The multilayer switch that has received the VRRP advertisement is configured to perform the following processing before determining whether the received network interface is in a blocking state by STP.
(Means 2-1)
A determination unit that determines whether or not the transmission source MAC address of the MAC sublayer header of the received packet is a virtual MAC address used in the virtual router.
(Means 2-2)
A determination unit that determines whether the received packet is a VRRP advertisement based on information of the IP header of the received packet.
(Means 2-3)
A database in which the physical MAC address set in the network interface of the device itself is registered in advance in the multilayer switch is provided, and the database is stored using the physical MAC address added to the VRRP advertisement in (Method 1) as a key. A determination unit that determines whether the received VRRP advertisement is transmitted from a master router other than the own device or whether the received VRRP advertisement is transmitted by the own device due to a loop configuration of the layer 2 network by searching.

  By these means, when the received VRRP advertisement is from the master router that constitutes the own device and the virtual router, the VRRP advertisement is received without being discarded due to the blocking factor even if the receiving network interface is in the blocking state. Make it possible. On the other hand, if the received VRRP advertisement is transmitted by the own device, the VRRP advertisement is discarded.

According to the first solution of the present invention,
Redundancy control is performed based on the spanning tree protocol, and one of a plurality of transfer devices becomes a master router, the other transfer device becomes a backup router, and the plurality of transfer devices constitute one virtual router by the virtual router redundancy protocol. In the network system,
A first transfer device that operates as the master router of a virtual router redundancy protocol, wherein the first transfer device transmits an advertisement packet for detecting a failure with identification information of the device added thereto;
A second transfer device that operates as the backup router of the virtual router redundancy protocol and transitions between a blocking state for blocking communication packets and a forwarding state for transferring communication packets during topology reconfiguration by the spanning tree protocol. Determining whether or not the identification information included in the received advertisement packet is the identification information of the own device. If the identification information is not the identification information of the own device, the advertisement packet is received regardless of the state of the spanning tree protocol. A redundant protocol coexistence system including two transfer devices is provided.

According to the second solution of the present invention,
Redundancy control is performed based on the spanning tree protocol, and one of a plurality of transfer devices becomes a master router, the other transfer device becomes a backup router, and the plurality of transfer devices constitute one virtual router by the virtual router redundancy protocol. In the network system,
A first transfer device that operates as the master router of a virtual router redundancy protocol, wherein the first transfer device transmits an advertisement packet for detecting a failure with identification information of the device added thereto;
A backup router that operates as the backup router of the virtual router redundancy protocol, and is configured to block between a blocking state that blocks communication packets and a second transfer device that transitions between forwarding states that transfer communication packets during topology reconfiguration by the spanning tree protocol. Prepared,
The second transfer device transfers an advertisement packet transmitted from the first transfer device by being in a forwarding state during topology reconfiguration,
The first transfer device receives the transferred advertisement packet, determines whether the identification information included in the received advertisement packet is the identification information of the own device, and in the case of the identification information of the own device, A redundant protocol coexistence system that discards advertisement packets is provided.

According to the third solution of the present invention,
In a redundant network, a first protocol that blocks a predetermined network interface so as to prevent a loop and forms a topology, one of a plurality of transfer devices is a master device, and the other transfer device is a backup device, A plurality of transfer devices constitute one virtual device, the master device communicates using identification information of the virtual device, and the backup device does not receive the notification packet transmitted from the master device, so that the master device In the network system in which the second protocol for detecting the failure of the system coexists,
A first transfer device that operates as the master device, wherein the first transfer device transmits the notification packet for detecting a failure of the second protocol with the identification information of the device added thereto;
A second transfer device that operates as the backup device and transitions between a blocking state for blocking communication packets and a forwarding state for transferring communication packets during reconfiguration of the topology according to a first protocol, It is determined whether or not the identification information included in the notification packet is the identification information of the own device. If the identification information is not the identification information of the own device, the notification packet of the second protocol is received regardless of the state of the first protocol. A redundant protocol coexistence system comprising the second transfer device is provided.

According to the fourth solution of the present invention,
Redundancy control is performed based on the spanning tree protocol, and one of a plurality of transfer devices becomes a master router, the other transfer device becomes a backup router, and the plurality of transfer devices constitute one virtual router by the virtual router redundancy protocol. The transfer device in a network system,
Controls the transition between the blocking state that blocks communication packets during the spanning tree protocol topology reconfiguration and the forwarding state that forwards communication packets, and operates as a virtual router master router to detect failures. A control unit for adding the identification information of the own device to the advertisement packet and transmitting the advertisement packet;
It is determined whether the identification information included in the received advertisement packet is the identification information of the own device. If the identification information is not the identification information of the own device, the advertisement packet is received regardless of the state of the spanning tree protocol. The identification information determination unit for discarding the advertisement packet,
A spanning tree state determination unit that discards or forwards input packets according to the state of the spanning tree protocol;
It is determined whether or not the received packet is an advertisement packet. If the received packet is an advertisement packet, the received packet is transferred to the identification information determining unit. If the received packet is not an advertisement packet, the received packet is transferred to the spanning tree state determining unit. There is provided the transfer apparatus including a protocol determination unit for transferring.

  According to the present invention, it is possible to prevent the master router from being erroneously detected by the backup router. Further, according to the present invention, when the topology of the STP is changed, the VRRP advertisement transmitted from the master router can be received by the backup router in the transient state regardless of the state of the STP.

Further, according to the present invention, even when the layer 2 network has a loop configuration, it is possible to prevent a packet loop by discarding the VRRP advertisement transmitted from the own apparatus. According to the present invention, it is possible to prevent switch CPU resource consumption by preventing packet loops.
When layer 2 / layer 3 redundancy is performed, in addition to combining STP and VRRP, GSRP (registered trademark) of AxalA Networks, ESRP (registered trademark) of Extreme Networks, and VSRP (registered trademark) of Foundry Networks However, since these are protocols unique to each vendor, they can be used only in a network composed of multi-layer switches supplied by each vendor. On the other hand, according to the present invention, since a multi-vendor protocol is used, the system can be installed without changing the device configuration in a system that performs redundancy control using STP and VRRP.

FIG. 1 is a network configuration diagram of a redundant protocol coexistence system in which redundancy control is performed using STP and VRRP.
The redundant protocol coexistence system includes, for example, a multilayer switch A (first transfer device) 101, a multilayer switch B (second transfer device) 102, and a layer 2 switch (third transfer device) 103.
The multilayer switch A (101) and the multilayer switch B (102) constitute a VRRP virtual router (113). In the example of FIG. 1, the multilayer switch A (101) operates as a master router in the VRRP virtual router (113), and the multilayer switch B (102) operates as a backup router in the VRRP virtual router (113). is doing.
The layer 2 switch (103) has a MAC address table (114) in which transfer destination information indicating a transfer destination switch or network interface is stored corresponding to the destination MAC address. For example, when receiving a packet from the host computer (104), the layer 2 switch (103) refers to the MAC address table (114) based on the destination MAC address, and transfers the packet according to the corresponding transfer destination information. Transfer to A (101) or multilayer switch B (102). The MAC address table (114) stores the address of the multi-layer switch of the master router as the transfer destination.
The router (105) is a router of the upstream network. The server (106) communicates with the wide area Ethernet network (107, 108) via the router (105). The wide area Ethernet network 1 (107) uses the multilayer switch A (101) as a gateway when viewed from the host computer (104). The wide area Ethernet network 2 (108) uses the host computer 104 multilayer switch B (102) as a gateway.

  In FIG. 1, the multilayer switch A (101), the multilayer switch B (102), and the layer 2 switch (103) perform redundancy control of the layer 2 network by STP. In the state of FIG. 1, in the multilayer switch B (102), the network interface connected to the multilayer switch A (101) is in a blocking state (109). The multilayer switch A (101) and the multilayer switch B (102) perform redundancy control of the layer 3 network between the router (105) and the host computer (104) by VRRP. The master router in the VRRP virtual router (113) is the multilayer switch A (101), and the backup router is the multilayer switch B (102). The VRRP advertisement (111) transmitted by the multicast switch A (101) of the master router reaches the multilayer switch B (102) of the backup router via the layer 2 switch (103). The VRRP advertisement (111) that has arrived at the multilayer switch B (102) through a route directly connected to the multilayer switch B (102) is in a blocking state due to the STP (109). The multi-layer switch B (102) discards it.

  As an example, a multilayer switch A (101) is connected as an edge switch of the wide area Ethernet network 1 (107), and a multilayer switch B (102) is connected as an edge switch of the wide area Ethernet network 2 (108). Within these wide area Ethernet networks, layer 2 network redundancy control is performed by STP. In FIG. 1, a traffic route when a packet is transmitted from the host computer (104) to the server (106) is indicated by a broken line (110).

First, the above problem will be described with reference to the system configuration shown in FIG.
FIG. 2 is an explanatory diagram (1) of the problem.
FIG. 2 shows a case where, for example, the STP topology change has occurred in the wide area Ethernet network 2 (108), and the state of the network interface of the multilayer router B (102) becomes the blocking state.
When the topology change of the STP occurs in the wide area Ethernet network 2 (108) in FIG. 2, the topology is reconfigured also in the multilayer switch B (102) connected as the edge switch of the wide area Ethernet network 2 (108). Done. In the transient state, the state of the network interface of the multilayer switch B (102) repeats the transition to the blocking state and the forwarding state. The multilayer switch B (102) that is the backup router of VRRP transmits the VRRP advertisement transmitted by the multilayer switch A (101) that is the master router of the virtual router (113) of the VRRP when the network interface transitions to the blocking state. (111) cannot be received. Therefore, the multilayer switch B (102) erroneously detects the failure of the multilayer switch A (101).

3 and 4 are explanatory diagrams (2) and (3) of the problem.
In FIG. 3, the VRRP advertisement is transmitted from the multilayer switch B (102), and the next hop of the route for the server (106) is changed to the multilayer switch B (102) in the layer 2 switch (103). Indicates the case. In FIG. 4, the layer 2 switch (103) having the multi-layer switch B (102) as the transfer destination corresponding to the virtual MAC address 1 transmits a packet to the multi-layer switch B (102). The multilayer switch B (102) shows a case where all the network interfaces are in a blocking state in accordance with the topology change in the wide area Ethernet network 2 (108).

  In FIG. 3, the multilayer switch A (101) and the multilayer switch B (102) are both master routers, and the VRRP advertisement (112) is also transmitted from the multilayer switch B (102). The layer 2 switch (103) that has received the VRRP advertisement (112) from the multilayer switch B (102) receives the virtual MAC address set in the transmission MAC address of the MAC sublayer header of the VRRP advertisement by MAC address learning. With the owner as the multilayer switch B (102), the identification information of the multilayer switch B (102) or the identification information of the received network interface is registered in the MAC address table (114) of its own device corresponding to the virtual MAC address. . Thereafter, when the layer 2 switch (103) receives a packet for the server (106) from the host computer (104) until the VRRP advertisement is received from the multilayer switch A (101), the MAC address table (114) is received. ), Since the transfer destination for the server (106) is the multilayer switch B (102), the layer 2 switch (103) transfers the packet to the multilayer switch B (102).

As shown in FIG. 4, when the reconfiguration of the STP topology is not completed in the multilayer switch B (102), the state of the network interface of the multilayer switch B (102) may be in a blocking state. In this case, the packet destined for the server (106) is discarded by the multilayer switch B (102) and communication is interrupted (FIG. 4).
FIG. 5 is a configuration diagram of VRRP advertisement in the present embodiment.
In the present embodiment, as shown in FIG. 5, the physical MAC address (301) of the transmission source device is assigned to the VRRP advertisement. For example, the physical MAC address assigned to the network interface of the master router that is the transmission source is added. The packet is transmitted with an L2 header and an L3 header added.

FIG. 6 shows a configuration diagram of the multilayer switch of the present embodiment. FIG. 7 shows a flowchart of the VRRP advertisement determination procedure in the present embodiment.
The multilayer switches A (101) and B (102) include, for example, a transmission source MAC address determination unit (201), a VRRP advertisement determination unit (202), a physical MAC address determination unit (203), and routing / switching. An engine (204) and an STP state determination unit (206) are included. These can be configured by hardware, for example. The multilayer switches A (101) and B (102) have software (control unit) 205 that realizes the VRRP protocol. For example, transmission / reception of VRRP advertisement, switching between master and standby, control of transition between blocking state and forwarding state, and the like are executed. This software can be executed by an appropriate processing unit.

  The transmission source MAC address determination unit (201) determines whether the transmission source MAC address set in the MAC sublayer header of the received packet is equal to the virtual MAC address of the virtual router (113) to which the own device belongs. The VRRP advertisement determination unit (202) analyzes the TYPE field of the MAC sublayer header of the received packet and the protocol field of the information of the IP header, and determines whether or not the received packet is a VRRP advertisement. The physical MAC address determination unit (203) determines whether the physical MAC address assigned to the VRRP advertisement in the present embodiment belongs to the own device. Further, the physical MAC address determination unit (203) has a database (2031) in which physical MAC addresses accommodated by the own device are registered in advance. The routing / switching engine (204) is a routing / switching engine of the multilayer switch, and forwards the packet. The STP state determination unit (206) determines the STP state of the input network interface.

By assigning the source physical MAC address to the VRRP advertisement, the source device is specified. Further, the mechanism for determining whether or not it is a VRRP advertisement allows processing other than the expected packet in accordance with the STP, thereby realizing the loop prevention function of the STP without impairing it.
As shown in FIG. 6, before the STP state determination unit (206) that determines the blocking state by STP of the receiving network interface, the source MAC address set in the MAC sublayer header of the received packet is the virtual router. A transmission source MAC address determination unit (201) for determining whether the virtual MAC address is in use is provided.

  When the multilayer switches A (101) and B (102) receive the packet, the source MAC address determination unit (201) refers to the source MAC address set in the MAC sublayer header, It is determined whether or not the virtual MAC address is used by the virtual router to which it belongs (S101, Procedure 1 in the figure). If the packet (208) has a virtual MAC address used by the virtual router to which the device belongs, the source MAC address determination unit (201) displays the TYPE field of the MAC sublayer header and the protocol field of the IP header. The packet (208) is sent to the VRRP advertisement determination unit (202) to be analyzed. On the other hand, the source MAC address determination unit (201) sends the other packet (207) to the STP state determination unit (206) that determines the STP state of the reception network interface.

  In the VRRP advertisement determination unit (202) that analyzes the TYPE field of the MAC sublayer header and the protocol field of the IP header, the value of the TYPE field set in the MAC sublayer header of the received packet is a value “ It is determined whether it is “0x0800” and the value of the protocol field of the IP header is “0x70” indicating VRRP (S103, S105, Procedure002 in the figure). When the value of the TYPE field is “0x0800” and the value of the protocol field of the IP header is “0x70”, the VRRP advertisement determination unit (202) is used in the virtual router to which the own device belongs. The packet (209) is sent to the physical MAC address determination unit (203) that determines the VRRP advertisement and determines the physical MAC address. On the other hand, the VRRP advertisement determination unit (202) sends the packet (210) to the STP state determination unit (206) that determines the STP state of the reception network interface otherwise. In accordance with the STP, the STP state determination unit (206) transfers the packet to the routing / switching engine (204) according to the forwarding state and the blocking state, or discards the packet (S115 to S119).

  In step S107, the physical MAC address determination unit (203) takes an offset for acquiring the physical MAC address (301) from the VRRP advertisement (S107). For example, the physical MAC address determination unit (203) takes an offset of 16+ (Count IP Addrs × 4) bytes from the head of the VRRP field. The physical MAC address determination unit (203) that determines the physical MAC address (301) assigned to the VRRP advertisement has a database (2031) in which the physical MAC addresses of the network interfaces accommodated by the device itself are registered. The physical MAC address determination unit (203) refers to the database (2031) and searches for an entry that matches the physical MAC address (301) included in the received VRRP advertisement with the key (S109). If there is a matching entry as a result of the search (S111), the physical MAC address determination unit (203) discards the packet because it is a packet transmitted from its own device (212, S113). Thereby, since the packet is not transmitted over the network again, a packet loop can be prevented. On the other hand, if there is no matching entry, the physical MAC address determination unit (203) is a VRRP advertisement transmitted from the master router of the virtual router to which the own device belongs. (S115). Thereafter, the packet (213) is transmitted to software (205) that implements the VRRP protocol.

FIG. 8 is an explanatory diagram (1) when the same network configuration as that of FIG. 1 is formed using the multilayer switches A (101) and B (102) to which the present embodiment is applied. According to the present embodiment, even when the STP topology change occurs in the wide area Ethernet network 2 (108) and the state of the network interface of the multilayer router B (102) becomes the blocking state (109), the VRRP advertisement is performed. (111) can be received.
FIG. 9 is an explanatory diagram (2) when the same network configuration as that in FIG. 1 is used by using the multilayer switches A (101) and B (102) to which the present embodiment is applied. According to the present embodiment, VRRP transmitted from the multilayer switch A (101) when the multilayer switch A (101), the multilayer switch B (102), and the layer 2 switch (103) are in a loop configuration. When the advertisement (111) reaches the multilayer switch A (101) through a loop, it is discarded.

  In the above description, the STP and VRRP are used, but a protocol in which these are extended or changed may be used. The physical MAC address added to the VRRP advertisement packet (notification packet) may be appropriate identification information for identifying the transmission source device. In this case, appropriate identification information for identifying the own device can be stored in the database (2031).

  The present invention can be applied to a system that performs redundancy control using, for example, VRRP and STP.

1 is a network configuration diagram of a fault error detection prevention system that performs redundancy control using STP and VRRP. FIG. Explanatory drawing (1) of a subject. Explanatory drawing (2) of a subject. Explanatory drawing (3) of a subject. The block diagram of VRRP advertisement. The block diagram of a multilayer switch. The flowchart figure in a multilayer switch. Explanatory drawing (1) at the time of setting it as the same network structure as FIG. 1 using this multilayer switch. Explanatory drawing (2) at the time of setting it as the same network structure as FIG. 1 using this multilayer switch.

Explanation of symbols

101, 102 Multilayer switch 103 Layer 2 switch 104 Host computer 105 Router 106 Server 107, 108 Wide area Ethernet network 109 Network interface 110 in a blocking state Traffic 111 Transmitted from multicast router A VRRP advertisement 112 Transmitted from multicast router B VRRP advertisement 113 Virtual router 114 MAC address table 201 Transmission source MAC address determination unit 202 VRRP advertisement determination unit 203 Physical MAC address determination unit 204 Routing / switching engine 205 Software (control unit)
206 STP state determination unit 207 Packet 208 whose source MAC address is different from its own virtual router MAC address 208 Packet whose source MAC address matches its own virtual router MAC address 209 Packet 210 determined as VRRP advertisement 210 VRRP advertisement Packet 211 determined to be other than the packet 211 Packet whose physical MAC address is different from the MAC address accommodated in the own device 212 The packet discarded because the physical MAC address matches the MAC address accommodated in the own device 213 VRRP protocol VRRP advertisement 214 sent to software that implements VRRP advertisement 301 sent to the network Physical MAC address

Claims (11)

Redundancy control is performed based on the spanning tree protocol, and one of a plurality of transfer devices becomes a master router, the other transfer device becomes a backup router, and the plurality of transfer devices constitute one virtual router by the virtual router redundancy protocol. In the network system,
A first transfer device that operates as the master router of a virtual router redundancy protocol, wherein the first transfer device transmits an advertisement packet for detecting a failure with identification information of the device added thereto;
A second transfer device that operates as the backup router of the virtual router redundancy protocol and transitions between a blocking state for blocking communication packets and a forwarding state for transferring communication packets during topology reconfiguration by the spanning tree protocol. Determining whether or not the identification information included in the received advertisement packet is the identification information of the own device. If the identification information is not the identification information of the own device, the advertisement packet is received regardless of the state of the spanning tree protocol. A redundant protocol coexistence system comprising two transfer devices.   The redundant protocol coexistence system according to claim 1, wherein the identification information is a physical MAC address of a transfer device that transmits an advertisement packet. An advertisement packet is forwarded by the second forwarding device when the second forwarding device is in a forwarding state during topology reconfiguration,
The said 1st transfer apparatus determines whether the identification information contained in the received advertisement packet is the identification information of an own apparatus, and discards an advertisement packet in the case of the identification information of an own apparatus. Redundant protocol coexistence system. The first and / or second transfer device is:
When operating as a master router of a virtual router, a control unit that adds and transmits identification information of its own device to an advertisement packet for failure detection; and
It is determined whether the identification information included in the received advertisement packet is the identification information of the own device. If the identification information is not the identification information of the own device, the advertisement packet is received regardless of the state of the spanning tree protocol. The identification information determination unit for discarding the advertisement packet,
A spanning tree state determination unit that discards or forwards input packets according to the state of the spanning tree protocol;
It is determined whether or not the received packet is an advertisement packet. If the received packet is an advertisement packet, the received packet is transferred to the identification information determining unit. If the received packet is not an advertisement packet, the received packet is transferred to the spanning tree state determining unit. The redundant protocol coexistence system according to claim 1, further comprising a protocol determination unit for transferring. The protocol control unit
A source MAC address determination unit that determines whether the source MAC address of the MAC sublayer header of the received packet is the virtual MAC address of the virtual router;
Whether the received packet is an advertisement packet by referring to the TYPE field of the MAC sublayer header of the packet and the protocol field of the IP header for the packet determined by the source MAC address determination unit as the virtual MAC address of the virtual router. The redundant protocol coexistence system according to claim 4, further comprising an advertisement determination unit that determines whether or not. Corresponding to the virtual address of the virtual router composed of the first and second transfer devices, transfer destination information for transferring the packet to the first or second transfer device operating as a master router is stored. 2. The apparatus according to claim 1, further comprising: a third transfer device that has an address table and transfers a packet to one of the first and second transfer devices according to the address table when a communication packet addressed to a virtual address is received. Redundant protocol coexistence system. The third transfer device, when receiving an advertisement packet including a virtual address from one of the network interfaces, stores the identification information of the network interface in the address table as transfer destination information corresponding to the virtual address,
7. The redundant protocol coexistence system according to claim 6, wherein when a packet addressed to a virtual address is received, the packet is transferred to either the first transfer device or the second transfer device via the network interface according to the address table.   The redundant protocol coexistence system according to claim 1, wherein the first and / or second transfer device is located at an edge of a network that is redundantly controlled by a spanning tree protocol. Redundancy control is performed based on the spanning tree protocol, and one of a plurality of transfer devices becomes a master router, the other transfer device becomes a backup router, and the plurality of transfer devices constitute one virtual router by the virtual router redundancy protocol. In the network system,
A first transfer device that operates as the master router of a virtual router redundancy protocol, wherein the first transfer device transmits an advertisement packet for detecting a failure with identification information of the device added thereto;
A backup router that operates as the backup router of the virtual router redundancy protocol, and is configured to block between a blocking state that blocks communication packets and a second transfer device that transitions between forwarding states that transfer communication packets during topology reconfiguration by the spanning tree protocol. Prepared,
The second transfer device transfers an advertisement packet transmitted from the first transfer device by being in a forwarding state during topology reconfiguration,
The first transfer device receives the transferred advertisement packet, determines whether the identification information included in the received advertisement packet is the identification information of the own device, and in the case of the identification information of the own device, A redundant protocol coexistence system that discards advertisement packets. In a redundant network, a first protocol that blocks a predetermined network interface so as to prevent a loop and forms a topology, one of a plurality of transfer devices is a master device, and the other transfer device is a backup device, A plurality of transfer devices constitute one virtual device, the master device communicates using identification information of the virtual device, and the backup device does not receive the notification packet transmitted from the master device, so that the master device In the network system in which the second protocol for detecting the failure of the system coexists,
A first transfer device that operates as the master device, wherein the first transfer device transmits the notification packet for detecting a failure of the second protocol with the identification information of the device added thereto;
A second transfer device that operates as the backup device and transitions between a blocking state for blocking communication packets and a forwarding state for transferring communication packets during reconfiguration of the topology according to a first protocol, It is determined whether or not the identification information included in the notification packet is the identification information of the own device. If the identification information is not the identification information of the own device, the notification packet of the second protocol is received regardless of the state of the first protocol. A redundant protocol coexistence system comprising the second transfer device. Redundancy control is performed based on the spanning tree protocol, and one of a plurality of transfer devices becomes a master router, the other transfer device becomes a backup router, and the plurality of transfer devices constitute one virtual router by the virtual router redundancy protocol. The transfer device in a network system,
Controls the transition between the blocking state that blocks communication packets during the spanning tree protocol topology reconfiguration and the forwarding state that forwards communication packets, and operates as a virtual router master router to detect failures. A control unit for adding the identification information of the own device to the advertisement packet and transmitting the advertisement packet;
It is determined whether the identification information included in the received advertisement packet is the identification information of the own device. If the identification information is not the identification information of the own device, the advertisement packet is received regardless of the state of the spanning tree protocol. The identification information determination unit for discarding the advertisement packet,
A spanning tree state determination unit that discards or forwards input packets according to the state of the spanning tree protocol;
It is determined whether or not the received packet is an advertisement packet. If the received packet is an advertisement packet, the received packet is transferred to the identification information determining unit. If the received packet is not an advertisement packet, the received packet is transferred to the spanning tree state determining unit. The transfer apparatus comprising a protocol determination unit for transfer.

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