JPH09224048A - Packet distribution hub - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a packet distribution hub capable of constructing a highly reliable duplex system for which switching time is short without requesting special LAN control to a server. SOLUTION: A control part 2 distributes a packet whose transmission destination address part is rewritten by an MAC (medium access control) address rewrite part 3 to the servers 20 and 30, stores an active system server among the respective servers 20 and 30 connected to a secondary side and performs control so as not to send out the packet from the server other than the active system server to a bus LAN 50. Further, the control is performed so as to send out the packet transmitted from the active system server connected to the secondary side to the bus LAN 50 after rewriting the transmission origin address part from the bus LAN 50 to the MAC address held in a MAC address holding part 4 in the MAC address rewrite part 3 or to send it out to the bus LAN 50 as it is without performing rewrite in the MAC address rewrite part 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a LAN connecting device, and more particularly to a LAN connecting device used for constructing a server duplication system that requires high reliability in a client / server system.

[0002]

2. Description of the Related Art In recent years, the Internet and the like, in which a large number of networks are integrated into one network by connecting a large number of independent networks to each other, have been rapidly spread. The Internet is TCP (Transmis)
sion Control Protocol) / IP (Internet Protocol)
This refers to a group of networks that communicate using a protocol called TCP.
A LAN (Local Area Network) that communicates by IP / IP is rapidly spreading, and in particular, the construction of client-server systems connected to LAN is increasing.

In a client / server system, the work of many clients connected to a LAN is undertaken by a small number of servers, so there is a strong demand for improvement in the reliability of the server that undertakes the work.

In order to increase the reliability of the server in the client / server system, a plurality of servers are installed so that even if one server fails, another server takes over the work. However, from the aspect of maintaining uniqueness of the MAC (Media access control) address of each server resulting from the connection form of LAN connection, as shown in FIG. There is a system that performs complicated control such that a plurality of servers appear to the client 300 and packets are separately sent to each server.

As a first conventional technique for constructing a duplex system by simple control without performing such complicated control, as shown in FIG. 5 (B), a certain server (A) 100 is installed. When the server goes down, the MAC address of the other server (B) 200 is replaced with the MAC address of the old server (“address A”) so that the client can see as if there is only one server. There are some (see Japanese Patent Application Laid-Open No. 4-27239).

Further, as a second conventional technique, a MAC address common to all servers is defined separately from the MAC address held individually by each server, and a client responds to this common MAC address. Packet transmission is performed so that each server receives packets transmitted to a common MAC address, and controls only the server operating as the active system to process the received packets. (Japanese Patent Laid-Open No. 64-74
844 and JP-A-61-150541).

[0007]

However, in the above-mentioned first and second conventional techniques, the MAC address of the server itself must be replaced or a common MAC address different from the normal MAC address must be added. Therefore, for example, from the viewpoint of maintaining the uniqueness of the MAC address, in a server in which the MAC address is fixedly set in a non-rewritable ROM or the like, a special mechanism must be incorporated in the server for replacing the MAC address. Also, there is a problem that a special mechanism must be incorporated in the server even when a common MAC address is added.

Further, in the above-mentioned first and second conventional techniques, since a plurality of servers are directly connected to the LAN and control is performed only by managing the MAC address, for example, the server operating as the active system is Despite the failure that caused another server to take over the work of the active server, the failed server did not completely stop the work, and only the operation work was processed. Stop and L
If the communication processing part to the AN is still in operation, if the new server takes over the MAC address, or if the new server processes a packet addressed to the common MAC address, There is a problem that packet processing is performed by both the failed server and the new server, and the processing control may be disrupted systematically.

Further, in the first conventional technique in which the server itself replaces the MAC address, the standby server does not communicate with the client while the active server is in operation, and therefore to what stage the work is processed. There is a problem that it is not possible to grasp what is happening, and when it is necessary to switch and take over the work, the work must be re-executed from the beginning, or it must be traced back long before the work is restarted.

Therefore, the present invention has been made in view of the above problems, and a highly reliable duplex system can be constructed using a general-purpose server without requiring the server to perform special LAN control. The purpose is to provide a packet distribution hub.

Further, according to the present invention, even if there are a plurality of servers, a packet sending system to a backbone LAN can be controlled without depending on its state or the like to construct a highly reliable duplex system. It is intended to provide a distribution hub.

Further, the present invention provides a packet distribution hub in which each server receives a packet from a client and advances the work individually, thereby shortening the server switching time required for taking over the work. The purpose is to

According to the present invention, as will be described later,
The packet distribution hub composed of a simple circuit or device can significantly improve the characteristics or performance and reliability of the client / server system.

[0014]

To achieve the above object, the present invention provides a backbone L to which one or a plurality of nodes are connected.
A primary LAN interface section that manages an interface with the AN, a secondary LAN interface section that manages an interface with a plurality of nodes connected to the secondary side, and a destination of a packet transmitted via the primary LAN interface section A MAC address rewriting unit that rewrites the address unit to the MAC address of each node connected to the secondary LAN interface unit, and sends a packet transmitted via the primary LAN interface unit to the secondary LAN interface unit. A packet distribution hub characterized in that the packet is distributed to each connected node.

Further, according to the present invention, of the packets to be transmitted from each node connected to the secondary LAN interface unit to the backbone LAN, only the packets from a node designated in advance are transmitted to the backbone LAN, and A packet distribution hub is provided which controls so that packets from other nodes are not transmitted to the backbone LAN.

Furthermore, the present invention provides the M on the backbone LAN.
A MAC that further includes a MAC address holding unit that holds an AC address, and that holds a source address unit of a packet to be transmitted from each node connected to the secondary LAN interface unit to the backbone LAN, in the MAC address holding unit. A packet distribution pub characterized by being rewritten to an address.

As described above, the packet distribution hub of the present invention includes a MAC address holding unit for holding a MAC address recognized from the backbone LAN and a destination address portion in a packet transmitted from the backbone LAN on the secondary side. Including a MAC address rewriting unit that rewrites the MAC address of each server connected to the server, and a control unit that controls the entire control. The control unit includes (1) a packet whose destination address unit is rewritten by the MAC address rewriting unit. To distribute to each server, and (2) control the storage of the active server among the servers connected to the secondary side so that packets from servers other than the active server are not sent to the backbone LAN. And (3) the source address part of the packet transmitted from the active server connected to the secondary side in the MAC address rewriting part C has a function of rewriting the basic LAN held in the C address holding unit to a MAC address and then sending it to the basic LAN, or a function of directly sending to the basic LAN without rewriting in the MAC address rewriting unit. There is.

Thus, according to the packet distribution hub of the present invention, from one packet transmitted from the client connected to the backbone LAN, the destination address part of the packet is the MAC of each server connected to the secondary side. Since packets for the number of servers whose addresses have been rewritten are generated and transmitted to each server, all servers can receive the packets from the clients.

Further, according to the packet distribution hub of the present invention, the packet transmitted from each server connected to the secondary side to the client connected to the backbone LAN is transmitted from the active server of the plurality of servers. Since only the transmitted packet is transmitted to the client and the packets from other servers are not transmitted to the client, the client can make it appear as if there is only one server.

[0020]

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

FIG. 1 is a block diagram showing the structure of a packet distribution hub according to the first embodiment of the present invention. As shown in FIG. 1, the packet distribution hub (HU) according to the present embodiment.
B) 1 is a client 40 and two servers (A) 20
Also, the present invention can be applied to a client / server system in which the server (B) 30 and the server (B) 30 are connected to each other via the backbone LAN 50. Although FIG. 1 shows the case where two servers (A) 20 and 30 (B) 30 are connected to the packet distribution hub 1 for convenience of description, three or more servers are connected. Of course, the same can be applied to the case.

Referring to FIG. 1, the packet distribution hub 1 according to the present embodiment has a primary LAN interface section 5 which controls a LAN interface with a backbone LAN 50 and a control section 2 which controls the packet distribution hub 1 as a whole. A MAC address holding unit 4 that holds the MAC address of the packet distribution hub 1 that can be seen from the backbone LAN 50;
A secondary LAN interface unit (A) 6 and a secondary LAN interface unit (B) that control LAN interfaces between the MAC address rewriting unit 3 that rewrites the C address and the server (A) 20 and the server (B) 30 respectively. 7
And a server (A) 20 and a server (B) apart from the transmission and reception of various data by the LAN connection with the client 40
It is composed of a control interface unit (A) 8 and a control interface unit (B) 9 that control the interfaces for notifying the packet distribution hub 1 of the respective states of 30.

It should be noted that the MAC address rewriting unit 3 is
For the packet transmitted from the AN 50, the destination address part in the packet is rewritten to the MAC address of the server (A) 20 or the server (B) 30, while for the packet transmitted from the active server, if necessary. The source address part in the packet is rewritten to the MAC address stored in the MAC address holding part 4.

Next, the operation of the packet distribution hub according to this embodiment will be described with reference to FIGS.

Referring to FIG. 1, as an initial operation, the packet distribution hub 1 passes through the control interface unit (A) 8 and the control interface unit (B) 9 to the server (A) 2
0 and each of the servers (B) 30 recognize which server is the active system, and the server (A)
20 and the MAC addresses of the server (B) 30 are read. Here, the server (A) 20 is the active system, and the MAC address of the server (A) 20 is “address A”.
Then, it is assumed that the MAC address of the server (B) 30 is “address B”.

Further, it is necessary to preset the address of the packet distribution hub 1 which can be seen from the backbone LAN 50 in the MAC address holding unit 4 of the packet distribution hub 1.
In this embodiment, the packet distribution hub 1 is set in advance at the manufacturing stage. Here, it is assumed that “address C” is set in the MAC address holding unit 4.
It should be noted that, as in a second embodiment of the present invention described later, it is possible to set an address of either the server (A) 20 or the server (B) 30 connected to the packet distribution hub 1. It is possible.

FIG. 2 is a view for explaining the flow of packets transmitted from the backbone LAN in the packet distribution hub according to the first embodiment of the present invention.

Referring to FIG. 2, after various settings are made in accordance with the above-mentioned initial operation, the packet distribution hub 1 incorporated in the client / server system in which the server (A) 20 is the active server is installed from the client 40. The packet received via the backbone LAN 50 is processed as follows. It is assumed that the packet handled by the packet distribution hub 1 is roughly composed of three blocks, which are a destination address part, a source address part, and a data part, arranged in this order from the beginning.

The packet distribution hub 1 is a client 40.
After receiving the packet transmitted from the primary LAN interface unit 5, the received packet is sent to the MAC address rewriting unit 3 via the control unit 2. Since the “address C” is stored and held in the MAC address holding unit 4 of the packet distribution hub 1, the client 40 sends the packet to the address C. That is, the “address C” is stored in the destination address part of the packet 53 transmitted from the client 40.

The MAC address rewriting unit 3 uses the destination address portion at the head of one packet 53 transmitted from the client 40 as the server (A) 20 and the server (B) 3.
Two packets 51 and 52 are generated by rewriting the respective MAC addresses of 0, that is, the "address A" and the "address B", respectively.

The two packets 51 and 52 generated by the MAC address rewriting unit 3 pass through the control unit 2 and pass through the secondary LA.
It is sent to each of the server (A) 20 and the server (B) 30 via each of the N interface unit (A) 6 and the secondary LAN interface unit (B) 7. In addition, M
Due to the rewriting in the AC address rewriting unit 3, the “address A” is stored in the destination address part of the packet 51 in the part received by the server (A) 20, and the part received by the server (B) 30. “Address B” is stored in the destination address portion of the packet 52 in FIG.

As the packets flow in the packet distribution hub 1 as described above, one packet 53 transmitted from the client 40 is sent to the server (A) 20 and the server (B) 30 respectively. Then, each server can receive it as if it was a packet originally sent to itself.

FIG. 3 is a diagram for explaining the flow of packets transmitted to the backbone LAN in the packet distribution hub according to the first embodiment of the present invention.

The flow of packets sent to the client 40 by each of the server (A) 20 and the server (B) 30 will be described with reference to FIG. The server (A) 20 designates the "address 40" which is the address of the client 40 as the destination address in the packet, and designates its own address "address A" as the source address to generate the packet 61. . Similarly, the server (B) 30
Generates a packet 62 by designating "address 40" as the destination address and "address B" as the source address.

These two packets 61 and 62 are sent to the packet distribution hub 1 and the control unit 2. The control unit 2 discards the packet 62 from the server (B) 30 other than the active system, and sends the packet 61 from the active server (A) 20 to the MAC address rewriting unit 3. Regarding the packet 61 sent from the control unit 2, the MAC address rewriting unit 3 rewrites the source address part of the packet 61 from “address A” to “address C”, that is, the address stored in the MAC address holding unit 4. To do. The rewritten packet 63 passes through the control unit 2 again and is sent to the client 40. That is, by such a rewriting process of the source address part, "address C" is stored in the source address part of the packet 63 in the portion received by the client 40.

As the packet flows through the packet distribution hub 1 as described above, the client 40 can receive the packet as if it is from the server having the "address C".

If the server (A) 20 cannot continue its work due to some failure, the server (B) 3
0 instructs the packet distribution hub 1 to switch the active server via the control interface (B) 9.
As a result, after that, the server (B) 30 becomes the active system, and the source address part of only the packet transmitted from the server (B) 30 is rewritten to “address C” and sent to the client 40. Even in this case, if the client 40 is used, it is as if "address C".
It looks like a packet was sent from the server.

Next, a packet distribution hub according to the second embodiment of the present invention will be described with reference to FIGS. 1 and 4. FIG. 4 is a diagram for explaining the flow of packets transmitted to the backbone LAN in the packet distribution hub according to the second embodiment of the present invention.

In the packet distribution hub according to the first embodiment of the present invention described above, as the address stored in the MAC address holding unit 4, a preset address different from the address of each server is used. In the packet distribution hub according to the second embodiment, the address of the active server obtained as a result of monitoring the initial server state is used as it is as the address stored in the MAC address holding unit 4.

Referring to FIG. 4, in the packet distribution hub 1 according to the present embodiment, the packets transmitted from the server (A) 20 and the server (B) 30 to the client 40 are transmitted to the servers (B) other than the active system. The packet 72 from 30) is discarded by the control unit 2 as in the first embodiment described above. On the other hand, the active server (A) 2
The packet 71 from 0 is sent to the client 40 as the packet 73 without being sent to the MAC address rewriting unit 3.

When the server (A) 20 cannot continue its work due to some failure, the server (B)
By the same instruction from the server 30 to switch the active system server, the server (B) 30 becomes the active system thereafter. The packet from the new active server (B) 30 after switching is not discarded by the control unit 20, but is not sent to the client 40 as it is and the MAC address rewriting unit 3
The source address part of the packet is "Address A"
And is sent to the client 40.
As a result, “address A” is set as the client 40.
There seems to be only a server called.

Although one embodiment of the present invention has been described above, the present invention is not limited to such an embodiment and includes various embodiments according to the principle of the present invention.

[0043]

As described above, according to the packet distribution hub of the present invention, the destination address part in a packet is located between a plurality of servers and clients, and the packets are transmitted between them. Or, in order to rewrite the source address part, the server itself
There is no need to rewrite addresses or add a common MAC address, and the client always sees one MAC address.

Further, according to the packet distribution hub of the present invention, since the packet from the server other than the active server is discarded, the active server fails and the operation cannot be continued. Even if there is a failure such that only the process of exchanging with the LAN continues to operate without stopping, the packet from the new server that has been switched can be transmitted to the client.

Further, according to the packet distribution hub of the present invention, the packet from the client is also transmitted to the standby system server, and the same process as the active server should be performed in parallel by the standby server. By doing so, it is possible to take over the operation from the middle of the operation rather than restarting the operation a long time before taking over the operation. Therefore, when a failure occurs in the active server, the standby server takes over the operation in a short time. You can

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a packet distribution hub according to first and second embodiments of the present invention.

FIG. 2 is a diagram for explaining a flow of packets transmitted from the backbone LAN in the packet distribution hub according to the first embodiment of the present invention.

FIG. 3 is a diagram for explaining the flow of packets transmitted to the backbone LAN in the packet distribution hub according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a flow of packets transmitted to a backbone LAN in a packet distribution hub according to a second embodiment of the present invention.

FIG. 5 is a diagram for explaining a packet flow in a conventional client / server system (duplication system).

[Explanation of symbols]

 1 packet distribution hub (HUB) 2 control unit 3 MAC address rewriting unit 4 MAC address holding unit 5 primary LAN interface unit 6 secondary LAN interface unit A 7 secondary LAN interface unit B 8 control interface unit A 9 control interface unit B 20 Server A 30 Server B 40 Client 50 Core LAN 51, 52, 53 Packet 61, 62, 63 Packet 71, 72, 73 Packet 100 Server A 200 Server B 300 Client

Claims (3)

[Claims] 1. A backbone LA to which one or a plurality of nodes are connected
A primary LAN interface unit that manages an interface with N, a secondary LAN interface unit that manages an interface with a plurality of nodes connected to the secondary side, and a destination of a packet transmitted via the primary LAN interface unit. A MAC address rewriting unit that rewrites the address unit to the MAC address of each node connected to the secondary LAN interface unit, and sends a packet transmitted via the primary LAN interface unit to the secondary LAN interface unit. A packet distribution hub characterized by being distributed to each connected node. 2. Regarding packets to be transmitted from the nodes connected to the secondary LAN interface unit to the backbone LAN, only packets from a node designated in advance are transmitted to the backbone LAN, and from other nodes. 2. The packet distribution hub according to claim 1, wherein the packet is controlled so as not to be transmitted to the backbone LAN. 3. A MAC address holding unit for holding a MAC address on the backbone LAN, further comprising: a source address unit of a packet transmitted from each node connected to the secondary LAN interface unit to the backbone LAN. MA held in the MAC address holding unit
The packet distribution hub according to claim 1 or 2, wherein the packet distribution hub is rewritten to the C address.