JP2022034323A - Communication system and communication control method - Google Patents

Abstract

To provide a system that can distribute a load while establishing an active-standby configuration in each server device.SOLUTION: A communication system of the present invention includes: a server device having a plurality of hosts, a switch unit, and a router unit; a first layer 3 switch having a first switch function unit and a first router function unit; and a second layer 3 switch having a second switch function unit and a second router function unit. A first sub-network is formed among all the components of the server device, the first layer 3 switch, and the second layer 3 switch; a second sub-network is formed between the router unit of the server device and the first layer 3 switch; a third sub-network is formed between the router unit of the server device and the second layer 3 switch; and each sub-network is used according to communication applications of the server device, the first layer 3 switch, and the second layer 3 switch.SELECTED DRAWING: Figure 1

Description

The present invention relates to a communication system and a communication control method, and can be applied to, for example, a communication system in which a plurality of server devices composed of a router function unit and a plurality of hosts are connected.

Conventionally, server devices are configured separately from network-connected devices such as switching hubs and routers, and a redundant network configuration is applied so that they can be used continuously even if a failure occurs between the connected devices. Was common (Patent Document 1 etc.). A conventional configuration example of the server device in consideration of fault tolerance is shown in FIG. 15, for example.

Also, nowadays, it is possible to operate multiple virtual hosts in one device by using virtualization technology, etc., and to operate the functions of switching hubs and routers in addition to the functions of hosts. Possible products are becoming available, and it is becoming possible to build more flexible network configurations. An example of a configuration of a server device having a host function and a router function in one device is shown in FIG. 16, for example.

Japanese Unexamined Patent Publication No. 2011-081588

However, in the case of the system configuration shown in FIG. 15, although the route can be switched even if a failure occurs in one place, it becomes the first transfer destination when the packet is transmitted from the host (server device). The device that uses the gateway address is limited to one device, and the transmission flow of the transmission traffic is as shown in FIG. That is, it is impossible to distribute the load to two layer 3 switches (routers) and transfer the load.

On the other hand, in the case of the system configuration shown in FIG. 16, by setting the IP address of the router function unit in the server device as the gateway address of the host, it is possible for the router function unit to select a route for transmission traffic from the host. Therefore, the load can be distributed and transferred to the two layer 3 switches by using the load distribution function of the route control protocol such as OSPF (Open Shortest Path First).

However, in the case of the system configuration shown in FIG. 16, even if an Active-Standby redundant configuration between two server devices is established and the two server devices try to share an IP address, the two hosts have different networks. Since the IP address cannot be shared between the two hosts, there is a problem that the redundant configuration of Active-Standby cannot function normally.

In view of the above problems, there is a demand for a communication system and a communication control method capable of efficient load balancing while establishing an Active-Standby configuration with a plurality of server devices.

The first aspect of the present invention is (1) a server device having a plurality of hosts, a switch unit, and a router unit, and (2) a first switch function unit and a first router function connected to the server device. A first layer 3 switch having a unit, and (3) a second layer 3 connected to the server device and the first layer 3 switch and having a second switch function unit and a second router function unit. A switch is provided, and (4) a first subnetwork is formed between all the components of the server device, the first layer 3 switch, and the second layer 3 switch, and (5) the server device. A second sub-network is formed between the router section and the first layer 3 switch, and (6) a third sub network is formed between the router section of the server device and the second layer 3 switch. A network is formed, and (7) each of the sub-networks is used according to the communication application between the server device and the first layer 3 switch and the second layer 3 switch.

The second invention has (1) a server device having a plurality of hosts, a switch section, and a router section, and a first switch function section and a first router function section connected to the server device. A communication system including a first layer 3 switch, a second layer 3 switch connected to the server device and the first layer 3 switch, and having a second switch function unit and a second router function unit. (2) The sub-network forming means is a first sub-network among all the components of the server device, the first layer 3 switch, and the second layer 3 switch. (3) The sub-network forming means forms a second sub-network between the router portion of the server device and the first layer 3 switch, and (4) the sub-network forming means. Formed a third sub-network between the router portion of the server device and the second layer 3 switch, and (5) the server device, the first layer 3 switch, and the second layer. It is characterized in that each of the above-mentioned sub-networks is used according to the communication use of the three switches.

According to the present invention, it is possible to efficiently distribute a load while establishing an Active-Standby configuration with a plurality of server devices.

It is a block diagram which shows the structure of the server apparatus which concerns on embodiment. It is a block diagram which shows the structure of the layer 3 switch which concerns on embodiment. It is a block diagram which shows the whole structure of the server system which concerns on embodiment. It is explanatory drawing which showed the structure of the table which shows the connection state for each server apparatus which concerns on embodiment. It is explanatory drawing which shows the example of the connection state by the connection state of the network which concerns on embodiment (the connection state of each of a server apparatus and both layer 3 switches). It is explanatory drawing which shows the kind of the sub-network which concerns on embodiment. It is explanatory drawing which shows an example of the configuration of the sub-network which concerns on embodiment, and the place where the IP address is used. It is a sequence diagram which shows the characteristic operation of the layer 3 switch which concerns on embodiment (the operation when the packet addressed to the server apparatus is received from another apparatus). It is a sequence diagram which shows the characteristic operation (the operation when the IP packet is forwarded from a host to another network) of the server apparatus which concerns on embodiment. It is a sequence diagram which shows the characteristic operation of the server apparatus which concerns on embodiment (the operation when the IP packet is forwarded to the host of another server apparatus). It is explanatory drawing which shows the example of the connection state change table which concerns on embodiment. It is explanatory drawing which shows the forwarding route (when the failure does not occur) of the broadcast packet forwarded from the layer 3 switch in the server system which concerns on embodiment. It is explanatory drawing which shows the forwarding route of the broadcast packet transferred from the layer 3 switch (in the case of failure between a layer 3 switch and a server device) in the server system which concerns on embodiment. It is explanatory drawing which shows the forwarding route of the broadcast packet forwarded from the server apparatus in the server system which concerns on embodiment. It is explanatory drawing which shows the configuration example (the 1) of the conventional server apparatus. It is explanatory drawing which shows the configuration example (the 2) of the conventional server apparatus. It is explanatory drawing which shows the transmission flow of the transmission packet at the time of failure of the conventional server device.

(A) Main Embodiment Hereinafter, the embodiment of the communication system and the communication control method according to the present invention will be described in detail with reference to the drawings.

(A-1) Configuration of Embodiment (A-1-1) Detailed Configuration of Server Device 1 FIG. 1 is a block diagram showing a configuration of a server device according to an embodiment.

The server device 1 includes an arbitrary number of hosts 11 (11-1 to 11-n), a router function unit 21, a switch function unit 31, and a transmission line 41 (41-1) connecting each host 11 and the switch function unit 31. ~ 41-n), a transmission line 42 connecting the router function unit 21 and the switch function unit 31, and a transmission line 51 (51-1 ~) for connecting an even number of the switch function unit 31 and the layer 3 switch 71 described later. It has 51-m) and 52 (52-1 to 52-m).

The server device according to the embodiment may be configured as hardware such as a dedicated IC chip equipped with each component shown in FIG. 1, or may be software-based mainly on a CPU and a program executed by the CPU. Although it may be configured, it can be functionally represented by FIG. Further, for example, each configuration shown in FIG. 1 may be provided by one hardware device, and each component may be realized as a virtual function.

Each host 11 provides a function of performing arithmetic processing, and has a function of processing traffic received from another device and responding to the processing result.

As a function of a general layer 2 switch, the switch function unit 31 can separate connection ports into a plurality of virtual sub-networks (VLANs), and is designated among devices connected to each sub-network. It has a function to transfer traffic to the destination device. Further, the switch function unit 31 has a function of suppressing the transfer of the broadcast frame transferred from the layer 3 switch 71 to another layer 3 switch 71.

As a general router function, the router function unit 21 searches for a route to the destination address of the received IP packet and forwards the packet to the searched route, and between the layer 3 switch 71 to be connected. It has a function to operate a route control protocol and exchange route information. Further, the router function unit 21 also has a function of distributing the load to a plurality of routes when there are a plurality of optimum routes by using a route control protocol such as OSPF.

(A-1-2) Detailed Configuration of Layer 3 Switch 71 FIG. 2 is a block diagram showing a configuration of a layer 3 switch according to an embodiment.

The layer 3 switch 71 includes a switch function unit 72, a router function unit 73, a transmission line 81 (81-1 to 81-n) for connecting the switch function unit 72 and each server device 1, a switch function unit 72, and the like. The transmission line 82 for connecting the layer 3 switch 71 of the above, the transmission line 83 for connecting the switch function unit 72 and the router function unit 73, and the router function unit and another device (for example, an external device) are connected. It has a transmission line 84 (84-1 to 84-O) for the purpose of. Hereinafter, the other layer 3 switch connected by the transmission line 82 will be referred to as an “other layer 3 switch”.

As a function of a general layer 2 switch, the switch function unit 72 can separate connection ports into a plurality of virtual sub-networks (VLANs), and is designated among devices connected to each sub-network. It has a function to transfer traffic to the destination device. Further, the switch function unit 72 has a function of monitoring the communication state with each server device, and monitors whether the state is “communication possible” or “communication impossible”.

Further, the switch function unit 72 has a function of notifying the communication state with each server device 1 when connected to the other layer 3 switch 71, and changes the content when the communication state with each server device 1 changes. It has a function of notifying the switch function unit 72 of the other layer 3 switch 71. The switch function unit 72 uses, for example, the connection state management table T1 as shown in FIG. 4A according to the monitoring state of the own layer 3 switch 71 and the notification content received from the other layer 3 switch 71. , Monitor the connection status of each server device 1 to be connected. Further, the status of each server device 1 is, for example, as shown in the connection status management table T2 of FIG. 4B, "no connection", "own connection", "other connection", "both connection". Manage with any of the four connection states.

FIG. 5 is an explanatory diagram showing an example of a connection state according to a network connection status (connection status of each of the server device and both layer 3 switches) according to the embodiment. 5 (A) shows one side of the layer 3 switch 71 and the server device 1 (between the layer 3 switch 71-2 and the server device 1) when each device has not failed. 5 (C) shows the case where a failure occurs between both layer 3 switches 71, and FIG. 5 (D) shows the case where a failure occurs between both layer 3 switches 71 and the server device 1 (both sides). When a failure occurs, FIG. 5 (E) shows that a failure occurs between one side of the layer 3 switch 71 and the server device 1 (between the layer 3 switch 71-1 and the server device 1) and between both layer 3 switches 71. It shows the connection status of the network when.

Further, when the switch function unit 72 receives the broadcast frame from the other layer 3 switch 71, if the connection state of the connected server device 1 is "bisystem connection", the switch function unit 72 connects to the server device 1. Provides a function of suppressing the transfer of broadcast frames. Further, when the switch function unit 72 receives the broadcast frame from the server device 1, the switch function unit 72 suppresses the transfer of the broadcast frame to the other layer 3 switch 71 when the connection state of the server device 1 is "bisystem connection". It has a function to do.

The router function unit 73 has the same functions as the router function unit 21 of the server device 1 described above.

(A-1-3) Overall Configuration and Sub-Network Configuration FIG. 3 is a block diagram showing an overall configuration of a server system according to an embodiment.

In FIG. 3, the server system 100 includes an arbitrary plurality of server devices 1 (1-1 to 1-p) and any even-numbered layer 3 switches 71 (71-1, 71-2, ..., 71-m1). , 71-m2), a transmission line 81 (81-1 ...) connecting each server device 1 and each layer 3 switch 71, and a transmission line 82 (82-1 ...) connecting between two layer 3 switches 71. Has.

In the server system 100, each of the two layer 3 switches 71 directly connected by the transmission line 82 is for establishing a redundant route when connecting to another network, and is one of the layers 3. It is configured so that it can be connected to other networks even via the switch 71.

FIG. 6A shows the type (contents) of the sub-network composed of the switch function unit 31 of the server device 1 and the switch function unit 72 of the layer 3 switch 71 in the server system 100. As shown in FIG. 6A, one overall VLAN including all hosts 11 of all server devices 1, router function units 21, and all layer 3 switches 71 is configured as a subnetwork, and one server device 1 is configured. (Router function unit 21 of the server device 1) and a VLAN including only one layer 3 switch 71 are configured by the number of server devices 1 × the number of layer 3 switches 71.

Further, each host 11 of the server device 1, the router function unit 21, and the router function unit 73 of the layer 3 switch 71 have an IP address according to FIG. 6B in order to communicate with other devices by the IP protocol. .. For example, the router function unit 21 of the server device 1 holds one address for the entire VLAN and the number of addresses for the number of layer 3 switches 71 that connect itself to the layer 3 switch 71. For example, in the configuration of FIG. 7, the router function unit 21 has one address for the entire VLAN, one address for the layer 3 switch 71-1, and one address for the layer 3 switch 71-2, for a total of three. Holds (uses) individual IP addresses. FIG. 7 shows an example of the configuration of the sub-network and the place where the IP address is used according to the embodiment.

In the server system 100 of this embodiment, when each host 11 and the layer 3 switch 71 transfer an IP packet to another device via the entire VLAN, an Ethernet (generally used) is used. It is assumed that the same method as the transfer method to (registered trademark) is used. For example, when transmitting an IP packet, if the MAC address corresponding to the IP address of the forwarding destination is held, the MAC address is set as the destination MAC address of the transmission packet and the packet is transmitted. On the other hand, if the MAC address corresponding to the transfer destination IP address is not held, the frame inquiring about the MAC address corresponding to the transfer destination IP address is forwarded by broadcast using the ARP protocol, and the corresponding IP address is held. By responding with the MAC address to be held, the device acquires the MAC address, sets it as the destination MAC address, and sends a packet. It should be noted that, for example, in the layer 3 switch 71, the above processing is executed by the switch function unit 72.

(A-2) Operation of the Embodiment Next, the operation of the server system 100 in the embodiment having the above configuration will be described.

(A-2-1) Operation when a packet addressed to a server device is received from another device by the layer 3 switch FIG. 8 shows a characteristic operation of the layer 3 switch according to the embodiment (packet addressed to the server device from another device). It is a sequence diagram which shows the operation) when is received.

First, when the layer 3 switch 71 receives an IP packet from another device in the router function unit 73 (S101), the layer 3 switch 71 searches for a route according to the destination address of the received packet (S102).

When the destination of the received packet is the host 11 of the server device 1, the router function unit 73 transfers the IP packet to the switch function unit 72 because the transfer destination is a subnetwork of the entire VLAN (S103).

Upon receiving the IP packet, the switch function unit 72 confirms with the entire VLAN whether or not the MAC address entry corresponding to the IP address of the destination host exists in the MAC table (S104). If the MAC address entry exists, the switch function unit 72 proceeds to the process of step S111 described later, while if the MAC address entry does not exist, the switch function unit 72 executes the next process.

If the MAC address entry does not exist, the switch function unit 72 broadcasts an ARP frame for inquiring the MAC address corresponding to the destination IP address to the entire VLAN (S105).

The switch function unit 31 of each server device 1 that has received the ARP frame transfers the ARP frame to each host 11 (S106). However, the switch function unit 31 performs a process of suppressing the transfer of the ARP frame to the other layer 3 switch 71 connected to the same whole VLAN.

When the host 11 receives the ARP frame (S107), if the IP address to be inquired is the IP address of its own host, the host 11 responds with the MAC address to be held in the ARP response frame and transmits it to the layer 3 switch 71. Processing is performed (S108).

The ARP response frame transmitted in step S108 is transferred by the switch function unit 31 of the server device 1 (S109) and received by the switch function unit 72 of the layer 3 switch 71 (S110).

The switch function unit 72 of the layer 3 switch 71 acquires a transfer destination MAC address from the received ARP response frame, sets it as the destination MAC address, and performs a process of transmitting a packet (S111).

The packet transmitted in step S111 described above is forwarded to the destination host 11 (S112) by the switch function unit 31 of the server device 1 and notified to the destination host 11 (S113). The MAC address information acquired by the switch function unit 72 of the layer 3 switch 71 is stored in the MAC table of the switch function unit 72, and if a packet addressed to the same IP address is received thereafter, an ARP frame is used. The MAC address registered in the MAC table is set as the destination MAC address and the packet is forwarded without performing the transmission process of.

Further, when the ARP frame in step S105 described above is sent to the other layer 3 switch 71 (S114), the layer 3 switch 71 on the receiving side executes the following processing.

When the layer 3 switch 71 receives a broadcast frame from another layer 3 switch 71 (the layer 3 switch 71 that transmitted the ARP frame in step S105 described above), the layer 3 switch 71 refers to the connection state management table T1 (FIG. 4) described above. Then, the connection status of each server device 1 is confirmed, and if the value of the connection status is "self-connected", the same frame is transferred to the server device 1.

On the other hand, the layer 3 switch 71 performs a process of not transferring the value of the connected state to the server device 1 in other cases. That is, when the value of the connection state is "no connection" or "other system connection", it cannot be transferred because it cannot communicate with the target server device 1. Then, when the connection state is "bisystem connection", although it is in a state of being able to communicate with the target server device 1, a process of suppressing the transfer is performed.

(A-2-2) Operation when an IP packet is transferred from the host 11 of the server device 1 to another network FIG. 9 shows a characteristic operation of the server device according to the embodiment (transferring an IP packet from the host to another network). It is a sequence diagram which shows the operation in the case of performing.

When forwarding an IP packet to another network, the host 11 first transmits the packet to the IP address of the router function unit 21 of the same server device 1 via the entire VLAN (S121).

When the switch function unit 31 receives the IP packet, the switch function unit 31 forwards the packet to the router function unit 21 (S122).

When the router function unit 21 receives an IP packet (S123), it searches for a route from the destination IP address value of the received packet (S124), and the router with respect to the address between the router of the layer 3 switch and the layer 3 switch that becomes the route. ⇔ Packets are transferred using the layer 3 switch-to-switch VLAN (S125). The router function unit 21 can also use the routing protocol function to perform load balancing transfer to a plurality of routes by using a function of distributing the optimum routes to a plurality of routes.

The packet transferred from the router function unit 21 in step S125 described above is transferred to the layer 3 switch 71 at the switch function unit 31 (S126).

Then, in the layer 3 switch 71, the switch function unit 72 transfers the IP packet received from the server device 1 side to the router function unit 73 (S127), and the router function unit 73 receives the IP packet (S128). , A route is searched from the destination IP address value of the received packet (S129), and the packet is forwarded to another network by forwarding to the searched route (S130).

(A-2-3) Operation when an IP packet is transferred from the host 11 of the server device 1 to the host 11 of another server device 1. FIG. 10 shows a characteristic operation of the server device according to the embodiment (other server device 1). It is a sequence diagram which shows the operation (operation when the IP packet is forwarded to the host 11 of the above).

When the host 11 of the server device 1-1 forwards an IP packet to the host 11 of another server device 1-2, the host 11 confirms whether or not the MAC entry corresponding to the IP address of the destination host exists in the MAC table. (S131). If the MAC address entry exists, the host 11 of the server device 1-1 proceeds to the process of step S144 described later, while if the MAC address entry does not exist, the host 11 executes the next process.

If the MAC entry does not exist, the host 11 of the server device 1-1 broadcasts an ARP frame for inquiring the MAC address corresponding to the IP address of the destination host to the entire VLAN (S132).

The switch function unit 31 of the server device 1-1 transfers the received ARP frame to the layer 3 switch 71 connected to the other host 11 (S133).

The switch function unit 72 of the layer 3 switch 71 that has received the ARP frame transfers the ARP frame to the other server device 1-2 (S134).

Further, the switch function unit 72 confirms the connection state of the server device 1-1 which is the transmission source (S135). The switch function unit 72 executes the next process when the connection state is "self-connected", while the switch function unit 72 proceeds to step S141 described later when the connection state is other (a state other than the self-connected). ..

When the connection state is "self-connected" in step S135 described above, the switch function unit 72 transfers the ARP frame to the other layer 3 switch 71 (S136).

After step S134 described above, the switch function unit 31 of the other server device 1-2 that has received the ARP frame transfers the ARP frame to each host 11 to which the ARP frame is connected (S137).

When each host 11 of the server device 1-2 receives the ARP frame (S138), if the inquiry target IP address is the IP address of the own host, the MAC address of the own host is set in the ARP response frame, and the transmission source An ARP response frame is transmitted to the host (host 11 of the server device 1-1) (S139).

The switch function unit 31 of the server devices 1-1 and 1-2 and the switch function unit 72 of the layer 3 switch 71 perform processing for transferring the ARP response frame, respectively (S140 to S142).

When the host 11 of the server device 1-1 receives the ARP response frame (S143), it acquires the MAC address value of the destination host, sets the acquired MAC address in the transmission packet, and transmits the IP packet to the destination host. (S144).

After step S144 described above, the switch function unit 31 of the server devices 1-1 and 1-2 and the switch function unit 72 of the layer 3 switch 71 perform processing for transferring IP packets (S145 to S147), respectively, and the destination. The IP packet is received by the host 11 of the above (S148).

Next, the processing of the layer 3 switch 71 on the receiving side after the processing of step S136 will be described.

When the switch function unit 72 of the layer 3 switch 71 receives a broadcast frame from another layer 3 switch 71 (the layer 3 switch 71 that transmitted the ARP frame in step S136 described above), the switch function unit 72 refers to the connection state management table T1 described above. Then, the connection state of each server device 1 is confirmed, and if the value of the connection state is "self-connected", the same frame is transferred to the server device 1. On the other hand, the layer 3 switch 71 performs a process of not transferring the value of the connected state to the server device 1 in other cases (when the connection is other than the own connection).

(A-2-3) Operation when a failure occurs Next, the operation when a failure occurs in the server system 100 will be described.

First, when the transmission line 81 between the layer 3 switch 71 and the server device 1 cannot communicate, the layer 3 switch 71 performs a route change process by the route control protocol used by the router function unit 73. Further, the switch function unit 72 changes the value of the connection state of the connection destination server device 1 according to, for example, the connection state change table T5 of FIG. 11A (updates the connection state management table T1). Further, the layer 3 switch 71 transmits a disconnection notification from the target server device 1 to the other layer 3 switch 71, and in the MAC table of the switch function unit 31, the transfer destination route is a transmission line in which a failure has occurred. For the entry that is, perform the process of deleting the transfer destination route.

On the other hand, in the other layer 3 switch 71 that has received the disconnection notification, in addition to the route change processing by the route control protocol used by the router function unit 73, in the switch function unit 72, for example, the connection state of FIG. 11B is shown. The value of the connection state of the connection destination server device 1 is changed according to the change table T6 (the connection state management table T1 is updated). Further, on the server device 1 side to which the transmission line that cannot be communicated is connected, the router function unit 21 performs a route change process according to the route control protocol to be used.

Further, when the transmission line 81 between the layer 3 switch 71 and the server device 1 is restored from non-communication to communicable, the layer 3 switch 71 performs a route change process by the route control protocol used in the router function unit 73. conduct. Further, the switch function unit 72 changes the value of the connection state of the connection destination server device 1 according to the connection state change table T7 of FIG. 11C, for example (updates the connection state management table T1). Further, the layer 3 switch 71 transmits a connection notification with the target server device 1 to the other layer 3 switch 71, and the transfer destination route is set to the other layer 3 switch 71 in the MAC table of the switch function unit 31. Performs processing to delete the transfer destination route for the entry that is the destination transmission line.

On the other hand, in the other layer 3 switch 71 that has received the connection notification, in addition to the route change processing by the route control protocol used in the router function unit 73, in the switch function unit 72, for example, the connection state shown in FIG. 11 (D). The value of the connection state of the connection destination server device 1 is changed according to the change table T8 (the connection state management table T1 is updated). Further, in the server device 1, the router function unit 21 performs a route change process on the other layer 3 switch 71 according to the route control protocol to be used.

Further, when the transmission line 82 directly connected between the two layer 3 switches 71 cannot communicate, the two layer 3 switches 71 (71-1, 71-2) are used by each router function unit 73. Performs route change processing using the route control protocol. Further, the switch function unit 72 changes the value of the connection state of the connection destination server device 1 according to, for example, the connection state change table T9 of FIG. 11 (E) (updates the connection state management table T1).

On the other hand, when the transmission line 82 directly connected between the two layer 3 switches 71 recovers from the impossibility of communication to the impossibility of communication, the two layer 3 switches 71 change the connection state with all the server devices 1 to other layers. 3 The process of notifying the switch 71 is performed, and after receiving the communication, for example, the value of the connection state of the connection destination server device 1 is changed according to the connection state change table T10 of FIG. 11 (F) (connection state management). Update table T1). Further, the router function unit 73 of the layer 3 switch 71 performs a process of changing the route according to the route control protocol to be used.

(A-3) Effect of Embodiment According to this embodiment, the following effects are exhibited.

In the above-mentioned server system 100, when a packet is transferred from another network to each host 11 of the server device 1, the broadcast transfer path is as shown in FIG. 12, and the broadcast frame transmitted from the layer 3 switch 71 is , It is possible to send a packet to each host 11 by the shortest route without causing a loop. As a result, all transmission lines 81 connecting the target server device 1 and each layer 3 switch 71 can be used for transfer to the specific host, so that each transmission line 81 should be used equally and effectively. Is possible. Further, in the broadcast forwarding route shown in FIG. 12, forwarding to the layer 3 switch 71 that is not directly connected is not possible, but the traffic of the service provided by the host 11 between the layer 3 switches 71 that are not directly connected. And route control protocol traffic is not sent, so it does not affect system operation.

Further, when a packet is transferred from the host 11 of the server device 1 to another network, the packet is forwarded to the IP address of the router function unit 21 in the server device 1, and then the router function unit 21 is optimally set by the routing protocol. It is possible to select a route and forward the packet, and it is also possible to distribute the load and forward the packet. That is, the transmission line 81 connecting each server device 1 and each layer 3 switch 71 can be used equally and effectively.

When a failure occurs between the server device 1 and the layer 3 switch 71, the switch function unit 72 of the layer 3 switch 71 deletes the MAC entry of the host addressed to the server device from the MAC table, thereby using ARP to make a new one. It becomes possible to search for a route. If there is no route to the destination address, the transfer route of the broadcast of the ARP inquiry frame transmitted from the layer 3 switch 71 is as shown in FIG. 13, so that the broadcast frame is bypassed to each server device 1 by bypassing the failure location. It is possible to transfer to, and it is possible to establish a new route.

When a packet is transmitted from the host 11 to another network when communication is not possible between the server device 1 and the layer 3 switch 71, the route applied by the router function unit 21 of the server device 1 and the router function unit 73 of the layer 3 switch 71. By making the route that bypasses the faulty part selected by the control protocol, it is possible to transfer by bypassing the faulty part.

When the path between the server device 1 and the layer 3 switch 71 becomes communicable from the non-communication state, the transfer path becomes the transmission line for the other layer 3 switch 71 in the switch function unit 72 of the layer 3 switch 71. By deleting the entry, it becomes possible to search for a new route using ARP, and it becomes possible to forward the packet to the host 11 of the server device 1 by the shortest route.

When packet forwarding is performed between hosts 11 of different server devices 1, the traffic flow when forwarding ARP frames by broadcast is as shown in FIG. 14, and broadcast traffic from host 11 is sent to another server by a plurality of routes. Since it is transmitted to the host 11 of the device 1, the receiving side receives duplicate frames, which deteriorates the transmission efficiency. However, if the system configuration has a small ratio of traffic sent and received between the hosts, the system operation can be performed. It has no effect.

From the above, in the state where no failure has occurred, the shortest route is used in both directions when transferring from each layer 3 switch 71 to the host 11 of the server device 1 and when transferring from the host 11 to another network. It is possible to use and distribute and transfer using multiple transmission lines, and since multiple hosts can be accommodated in the same subnetwork while effectively using the transmission lines, the application of the Active-Standby system. Is also possible. Further, even if a failure occurs between the layer 3 switch 71 and the server device 1, it is possible to transfer by bypassing the failure point in both directions.

1 ... Server device, 11 ... Host, 21 ... Router function unit, 31 ... Switch function unit, 41, 42, 51, 52, 81, 82, 83, 84 ... Transmission line, 71 ... Layer 3 switch, 72 ... Switch function Unit, 73 ... Router function unit, 100 ... Server system, T1, T2 ... Connection status management table, T3, T4 ... Subnetwork management table, T5 to T10 ... Connection status change table.

Claims (5)

A server device having a plurality of hosts, a switch unit, and a router unit,
A first layer 3 switch connected to the server device and having a first switch function unit and a first router function unit.
A second layer 3 switch connected to the server device and the first layer 3 switch and having a second switch function unit and a second router function unit is provided.
A first subnet network is formed between all the components of the server device, the first layer 3 switch, and the second layer 3 switch.
A second subnetwork is formed between the router portion of the server device and the first layer 3 switch.
A third subnetwork is formed between the router portion of the server device and the second layer 3 switch.
A communication system characterized in that each of the sub-networks is used according to the communication application between the server device and the first layer 3 switch and the second layer 3 switch. Each layer 3 switch of the first layer 3 switch and the second layer 3 switch monitors the connection state of the server device to be connected.
The communication system according to claim 1, wherein each layer 3 switch determines whether or not to transfer a received broadcast frame according to a connection state of the server device. The communication system according to claim 1 or 2, wherein the switch unit of the server device suppresses the transfer of a broadcast frame received from the first layer 3 switch or the second layer 3 switch. The communication system according to any one of claims 1 to 3, wherein the host, the switch unit, and the router unit of the server device are configured by a virtualization technique. A server device having a plurality of hosts, a switch section, and a router section, a first layer 3 switch connected to the server device and having a first switch function section and a first router function section, and the server. A communication control method used in a communication system connected to a device and the first layer 3 switch and including a second layer 3 switch having a second switch function unit and a second router function unit.
The sub-network forming means forms a first sub-network among all the components of the server device, the first layer 3 switch, and the second layer 3 switch.
The sub-network forming means forms a second sub-network between the router portion of the server device and the first layer 3 switch.
The sub-network forming means forms a third sub-network between the router portion of the server device and the second layer 3 switch.
A communication control method characterized in that each of the sub-networks is used according to the communication application between the server device and the first layer 3 switch and the second layer 3 switch.

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