JP2000261485A - Network address converting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a network address converting system that quickly relays a data packet between a client and a server under a client-server environment where a plurality of servers share loads of tasks of the same kind. SOLUTION: The same IP address is given to server computers connected to a plurality of server connection ports 10, 20 and conducting decentralizing processing, the re-configuration processing of a data packet is omitted for a client-server communication and an address transforming device 1 having an IP address transforming mechanism 2 and address conversion databases 3-5 conduct inter-network address conversion processing limited only to an inter- server communication.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a network address translation system, and more particularly to an address translation system for an inter-network connecting device that relays data packets between a plurality of networks.

[0002]

2. Description of the Related Art Conventionally, an internetwork environment in which a plurality of networks are interconnected via a network connecting device has been prepared, and a terminal device (hereinafter, referred to as a client) and a remote server machine (hereinafter, referred to as a host).
And data communication with the server.

When constructing an internetwork, an address (TCP / IP (T) of the third layer (hereinafter referred to as a network layer) of OSI is used to identify a host / client.
(ransmission Control Protocol / Internet Protocol)
In communication, it is necessary to assign an IP address) to a host and a client. Here, a description will be given assuming that the address of the network layer is an IP address.

[0004] In recent years, the workload of a host has tended to increase compared to the throughput of a host, and a client / server environment in which the load of the workload is distributed by preparing a plurality of server machines for processing the same type of business. Has increased.

However, in order to perform the above-mentioned load distribution without making each client aware of the IP addresses of all servers, a network connection device installed between the client and the server assigns one virtual IP address to the client side. Prepared, the network connection device converts the network address in the data packet into a unique IP address of each server each time each client accesses the above-mentioned virtual IP address, and performs a task requested by the client on a plurality of servers. A load balancing method (Load Balancing) is spreading.

An example of the above-described network address translation is disclosed in Japanese Patent Application Laid-Open No. 10-154995, entitled "Gateway Device and Packet Relay Method".

The gateway device disclosed in this publication is a device in which a user network composed of a plurality of terminals is connected to an external network as one terminal, and a plurality of terminals can communicate substantially simultaneously. As a means for realizing this, in a gateway device that relays a packet between a local network and an external network, a first device that converts a header of a packet transferred from at least one terminal of the local network to the external network into a header unique to the gateway device. Conversion means, a conversion table for storing conversion contents of the first conversion means, and a second conversion means for reversely converting a header of a packet transferred from the external network to the local network into a header for a terminal of the local network. And operates as a layer 3 relay device for a local network and operates as one terminal for an external network.

[0008] Also, one of the other network address translations
An example is disclosed in JP-A-10-23074.

The system disclosed in this publication is a system in which a server is switched from an active server to a standby server in a client-server environment without changing settings on the client side. As a method of realizing this, network monitoring means for monitoring the operation of a plurality of servers connected to the network on the server side, and virtually setting the IP address of a specific server connected to the network as the IP address of another server And a server switching unit for performing server switching for substituting a function of a specific server by another server, and a data packet transmitted / received between the specific server and the client between the server and the client whose server has been switched. Packet conversion means for converting the data packets into data packets transmitted and received between them.

[0010]

A characteristic relating to a data packet relay speed in load balancing is that data packets are relayed between a client and a server as quickly as possible in order to speed up client operations. The relay of data packets between the servers does not directly affect the client's business, so that some overhead is allowed.

However, the above-mentioned Japanese Patent Application Laid-Open No. 10-15 / 1998
The gateway device disclosed in Japanese Patent No. 4995 has a problem that it takes more time to relay a data packet between a client and a server than communication between servers. The reason is,
Since the IP address accessed by the client is one virtual IP address that can be said to be representative of multiple servers,
In order to relay a data packet between a client and a server, it is necessary to convert a network address between a virtual IP address and a unique IP address possessed by each server. Because it took a long time to broadcast.

Further, the network system disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 10-23074 has a problem that it takes time to relay data packets between each client computer and the backup server. The reason is that the IP address accessed by the client is the IP address of the active server, and the IP address of the active server and the IP address of the standby server must be converted for relaying data packets between the client and the standby server. This is because the execution of the address conversion process requires time for relaying data packets between the client and the backup server.

An object of the present invention is to provide a network address translation method for more quickly relaying data packets between a client and a server in a client-server environment in which the same kind of work is load-balanced by a plurality of servers. Is to do.

[0014]

In order to solve the above-mentioned problems, a network address translation system according to the present invention employs the following characteristic configuration.

(1) In a network address translation method of an inter-network connecting device for relaying a data packet between networks having a plurality of client network connection ports and a server connection port, the destination of the data packet on the network is the server. Means for knowing that there is, a means for knowing that the source of the data packet is the server, and a destination network address in the data packet when the destination and the source of the data packet are both the server. A network address translation method comprising: means for translating an original network address; and means for storing a translation image of the network address.

(2) The network address conversion method according to (1), further comprising means for storing a correspondence between the physical address of the server and the network address, and means for obtaining the physical address from the network address.

(3) In a network in which the same kind of work is load-shared by a plurality of server computers and performs data packet communication with a plurality of client computers, an IP (Internet Protocol) address is provided between the server computers and the client computers. IP address translation device having a translation function of
The address translation device includes a server connection port of the network, a client network connection port, an IP address translation mechanism for a data packet between the server connection port, and an address translation database storing address translation data for the IP address translation. And a network address translation system.

(4) The server computer has the same I
The network address translation method according to the above (3), wherein the P address is allocated. The present invention relates to an address conversion method for an inter-network connecting device that relays a data packet between them.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a network address translation system according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a first embodiment according to the present invention. In FIG. 1, an address translation device 1 is a network connection device provided with an address translation method according to the present invention. The address translator 1 has four physical network connection ports, each of which has a first server connection port 10, a second server connection port 20, a first client network connection port 30, 2 client network connection ports 40. The address translation device 1 includes an IP address translation mechanism 2 for rewriting an IP address of a data packet between server connection ports, and address translation database units 3, 4, and 5 for storing address translation data for IP address translation. It has.

The first server connection port 10 includes a first data packet transmitting unit 11 for transmitting a data packet to a server computer, and a first data packet receiving unit 12 for receiving a data packet from the server computer.
And a first address resolution unit 13 for determining a route of the data packet, that is, a physical port to which the data packet is transmitted, from a destination IP address of the data packet received from the server computer. Similarly, the second server connection port 20 is connected to the second data packet transmitting unit 21
, A second data packet receiving unit 22 and a second address resolution unit 23. In addition, the first client network connection port 30 includes a third data packet transmitting unit 31, a third data packet receiving unit 32, and a third
And an address resolution unit 33. Similarly, the second client network connection port 40 includes a fourth data packet transmitting unit 41 and a fourth data packet receiving unit 4.
2 and a fourth address resolution unit 43.

The data packet transmission units 11, 21, 31,
Reference numeral 41 has a function of generating traffic to the network to which each port is connected, and transmits a data packet given from inside the address translation device 1 to the connected network.

The data packet receiving units 12, 22, 32,
42 can read data packets passing over the network to which each port is connected. At this time, an error check or the like of the received packet is also performed as necessary.

Address resolution units 13, 23, 33, 43
Uses the destination IP address of a packet received from the network connected to each port as a key, determines the route of the data packet, and passes the data packet to the data packet transmission unit of the corresponding physical port.

In particular, the address resolution units 33 and 43 of the client network connection ports 30 and 40 determine the destination IP address of the data packet and the IP address of the server computer.
If the addresses match, a function of selecting one server computer from a plurality of server computers and deciding the route of the data packet is provided to distribute the load of the server computer processing capacity.

Next, the operation of the address resolution units 33 and 43 of the client network connection ports 30 and 40 will be described with reference to FIG.
This will be described with reference to the flowchart of FIG.

First, in step S11, the destination IP address of the received packet passed from the data packet receiving unit is read. The read IP address is compared with the IP address of the server computer in step S12. If they match, the process in step S13 is performed. If they do not match, the process in step S15 is performed.

If the received packet is a data packet addressed to a server computer, in step S13, one server computer is selected from the plurality of server computers, and the route of the data packet is determined. Next, in step S14, the received packet is passed to the data packet transmitting unit of the physical port corresponding to the route determined in step S13.

If the received packet is a data packet addressed to the client computer, in step S15, a physical port connected to the network to which the destination IP address belongs is obtained from the routing table, and sent to the data packet transmitting unit of the corresponding physical port. Pass the received packet.

The address resolution units 13 and 23 of the server connection ports 10 and 20 are connected to the address conversion database units 4 and 5, respectively, and the destination IP address of the data packet matches the IP address of the server computer. In this case, the IP address conversion mechanism 2 is sent to the data packet transmission unit of the physical port corresponding to the route of the data packet.
It has a function to pass through.

Next, the operation of the address resolution units 13 and 23 of the server connection ports 10 and 20 will be described with reference to the flowchart of FIG. First, in step S21, the destination IP address of the received packet passed from the data packet receiving units 12, 22 is read. The read IP address and the IP addresses of all the server computers registered in the address conversion database unit are stored in step S22.
IP addresses that match in the address translation database
If the address has been registered, the process of step S23 is performed. If there is no matching IP address, the process proceeds to step S23.
Step 24 is performed.

If the received packet is a data packet addressed to the server computer, the data packet is passed to the IP address translator 2 in step S23. If the received packet is addressed to the client computer, in step S24, a physical port connected to the network to which the destination IP address belongs is obtained from the routing table.
The received packet is passed to the data packet transmitting unit of the corresponding physical port.

The IP address conversion mechanism 2 has a function of rewriting a destination IP address and a source IP address in a data packet between a plurality of servers.

The address translation database unit 3 stores how to rewrite the destination IP address and the source IP address of a data packet passing between all servers connected to the address translation device 1. . FIG. 8 shows an example of this address conversion database.

The contents of the databases of the address translation database units 4 and 5 are
Matches the contents of the database of.

Next, FIG. 2 shows a network configuration diagram of a client-server environment using the address translator 1. In FIG. 2, a server computer 100 has a first server connection port 10 of the address translator 1, a server computer 200 has a second server connection port 20 of the address translator 1, and a client network 30.
0 is the first client network connection port 30 of the address translator 1 and the client network 40
0 is connected to the second client network connection port 40 of the address translation device 1.

The client network 300 includes a client computer 301 and a client computer 302, and the client network 400 includes a client computer 401 and a client computer 402.

The configuration of the embodiment has been described in detail above.
The means for selecting one server from a plurality of servers by load distribution and the means for determining a route from the destination IP address of a received data packet in the address resolution units 13 and 23 are well known to those skilled in the art. Since it is not directly related to the present invention, its detailed configuration is omitted.

Next, the operation of the first embodiment of the network address translation system according to the present invention will be described with reference to FIGS.

In this embodiment, the IP addresses of the server computer 100 and the server computer 200 are both assigned 127.80.2.1. Further, the IP address of the client computer 301 is 10.32.3.1, the IP address of the client computer 302 is 10.32.3.2, and the IP address of the client computer 401 is 10.3.
2.4.1 and the client computer IP address 10.32.4.2 are assigned.

However, in the server computer 100, the IP address of the server computer 200 is set to 12
It will be recognized as 7.80.2.3. Similarly, the server computer 200 recognizes the IP address of the server computer 100 as 127.80.2.2.

That is, the server computer 100 and the server computer 200 have the same IP address 127.
Although 80.2.1 is assigned, when a data packet is sent from the server computer 100 to the server computer 200, the destination IP address is set to 127.8.
When the data packet is sent from the server computer 200 to the server computer 100, the destination IP address is set to 127.80.2.2.

In the first operation description, the flow of a data packet in the address translation device 1 when a data packet is thrown from the client computer 301 to the server computer will be described.

The data packet transmitted by the client computer 301 is transmitted to the client network 300
To the client network connection port 30 of the address translation device 1 via The destination IP address of this data packet is the IP address 127.80.2.1 of the server computer, and the source IP address is the IP address 1 of the client computer 301.
0.32.3.1.

The address translator 1 confirms that the data packet is a correct data packet by the data packet receiving section 32 and then passes it to the address resolving section 33. The address resolution unit 33 determines the route of the data packet according to the flowchart shown in FIG.

First, in step S11, the destination IP address of the data packet received by the client network connection port 30 is read. In this example, step S
11 is 127.80.
2.1. Next, in step S12, the destination IP address of the data packet is compared with the IP address of the server computer (127.80.2.1 in this example). As a result of the comparison, they match, so step S13 is performed. In step S13, one of the two server computers is selected to distribute the load of the server computer processing. Here, it is assumed that the server computer 200 has been selected. Lastly, in step S14, the data packet is transferred via the path 35 to the data packet transmitting section 21 of the server connection port 20 to which the server computer 200 is connected.

The data packet transmitting section 21 transmits the data packet given via the path 35 to the network to which the physical port 20 is connected. As a result, the server computer 200
1 will be received. At this time, the IP address of this data packet is not rewritten inside the address translator 1.

Next, in the second operation description, the flow of a data packet in the address translator 1 when a data packet is thrown from the server computer 200 to the client computer 301 will be described.

The data packet transmitted by server computer 200 reaches server connection port 20 of address translator 1. The destination IP address of this data packet is the IP address 10.32.3.1 of the client computer 301, and the source IP address is the IP address 127.80.
2.1. The address translator 1 checks that the data packet is a correct data packet by the data packet receiving unit 22 and then passes it to the address resolving unit 23. The address resolution unit 23 determines the route of the data packet according to the flowchart shown in FIG.

First, in step S21, the destination IP address of the data packet received by the server connection port 20 is read. In this example, the destination IP address read in step S21 is 10.32.3.1. next,
In step S22, the destination IP address of the data packet is compared with the IP address of the server computer. The IP addresses of all server computers connected to the address translator 1 are stored in the address translation database 5
Registered in. The contents of the database in this example have been illustrated earlier. Since an IP address that matches the destination IP address read in step S21 is not registered in the address conversion database unit 5, the result of the comparison is a mismatch, and step S23 is performed.

In step S23, the client network 3 to which the client computer 301 belongs
The data packet is passed via the path 25 to the data packet transmission unit 31 of the client network connection port 30 to which 00 is connected. Data packet transmission unit 31
Transmits the data packet given via the path 25 to the network to which the physical port 30 is connected.
As a result, the client computer 301 receives the data packet from the server computer 200. At this time, the IP address of this data packet is not rewritten inside the address translator 1.

Next, in the third operation description, the client computer 301 transmits
Address translation device 1 when a data packet is thrown to
The flow of the data packet in the inside will be described.

The data packet transmitted by the client computer 301 is transmitted to the client network 300
To the client network connection port 30 of the address translation device 1 via The destination IP address of this data packet is
Is the IP address of 10.3.4.2.2.
The address is the IP address 10.32.3.1 of the client computer 301.

The address translator 1 confirms that the data packet is a correct data packet by the data packet receiving section 32 and then passes it to the address resolving section 33. The address resolution unit 33 determines the route of the data packet according to the flowchart shown in FIG.

First, in step S11, the destination IP address of the data packet received by the client network connection port 30 is read. In this example, step S
11 is 10.32.
4.2.

Next, in step S12, the destination IP address of the data packet is compared with the IP address of the server computer (192.80.2.1 in this example). As a result of the comparison, since they do not match, step S15 is performed. Finally, in step S15, the route 3 is sent to the data packet transmission unit 41 of the physical port 40 connected to the client network 400 to which the destination IP address of the data packet (in this example, 10.32.4.2) belongs.
6 to pass the received packet.

The data packet transmitting section 41 transmits the data packet given via the path 36 to the network to which the physical port 40 is connected. As a result, the client computer 402 receives the data packet from the client computer 301.
At this time, the IP address of this data packet is not rewritten inside the address translator 1.

Next, in a fourth operation description, a flow of a data packet in the address translation device 1 when a data packet is thrown from the server computer 200 to the server computer 100 will be described.

The data packet transmitted by the server computer 200 reaches the server connection port 20 of the address translation device 1. The destination IP address of this data packet is the IP address 127.80.2.
2 and the source IP address is the IP address 127.80.2.1 assigned to the server computer 200.
It is.

The address translator 1 confirms that this data packet is a correct data packet by the data packet receiving section 22 and then passes it to the address resolving section 23. The address resolution unit 23 determines the route of the data packet according to the flowchart shown in FIG. First, in step S21, the destination IP address of the data packet received by the step server connection port 20 is read. In this embodiment, the IP address read in S21 is 12
7.80.2.2.

Next, in step S22, the destination IP address of the data packet is compared with the IP address of the server computer. The IP addresses of all server computers connected to the address translator 1 are registered in the address translation database unit 5. The contents of the database in this example have been described above. Since an IP address that matches the destination IP address 127.80.2.2 read in step S21 is registered in the address conversion database unit 5, the result of the comparison is a match, and the result is step S2.
Perform Step 3.

In step S23, the address resolution unit 23
Passes the received packet to the IP address translation mechanism 2 via the path 24.

When receiving the data packet via the path 24, the IP address translator 2 rewrites the destination IP address and the source IP address of the data packet according to the flowchart shown in FIG.

First, in step S31, the source IP address of the data packet is rewritten. In this operation description, the data packet reception port is the server connection port 20. Since the IP address translator 2 has received the data packet via the path 24, it knows that the data packet receiving port is the server connection port 20. Further, the IP address conversion mechanism 2 searches the IP address corresponding to the server computer connected to the server connection port 20 using the database of the address conversion database unit 3. In this embodiment, as shown in FIG. 5, the server computer connected to the server connection port 20 is the server computer 200, and the IP address corresponding to the server computer 200 is 127.8.
It turns out that it is 0.2.3. Therefore, the IP address translator 2 rewrites the source IP address of the data packet to 127.80.2.3.

Next, in step S32, a transmission port is determined from the destination IP address. In this description of the operation, the destination IP address of the data packet received by the address translator 1 is 127.80.2.2. This is because the server computer 200
This is because the P address is recognized as 127.80.2.2. The IP address translation mechanism 2 searches the physical port corresponding to the IP address 127.80.2.2.2 using the database of the address translation database unit 3. In this example, it can be seen from FIG. 1 that the physical port corresponding to 127.80.2.2.2 is the server connection port 10.

Next, in step S33, the destination IP address of the data packet is rewritten to the IP address of the representative server. In this example, from FIG. 8, the IP address of the representative server is registered as 127.80.2.1. The IP address conversion mechanism 2 rewrites the destination IP address of the data packet to 127.80.2.1.

Lastly, the IP address translator 2 rewrites the IP address of the data packet.
At 34, the checksum of the IP header is recalculated.

When all the processes in FIG. 5 have been completed, the IP address translator 2 passes the data packet to the data packet transmitter 11 corresponding to the transmission port determined in step S32. The data packet transmitting unit 11 transmits a data packet provided via the path 17 to a network to which the physical port 10 is connected.

FIG. 9 shows an IP address conversion image of a data packet between server computers in this example. The conversion image of the IP address in this operation example is shown in the upper part of FIG. 9 shows an IP address conversion image at the time of data packet relay from the server computer 100 to the server computer 200.

As a result, server computer 100 receives the data packet from server computer 200. At this time, the IP address of the data packet received by the server computer 100 is rewritten by the address translator 1, and the destination IP address is 127.
80.2.1 and the IP address assigned to the server computer 100 is also 127.80.2.1, so the server computer 100 determines that the data packet is addressed to itself. Also, the server computer 100
The source IP address of the data packet received by is 1
27.8.2.3, the server computer 10
0 indicates that the source of the data packet is the server computer 20
Know that it is 0.

As described above, in the above embodiment, the relay of a data packet between a plurality of server computers is as follows.
Although the IP address is converted, the relay of the data packet between the client computer and the server computer is not performed, so that the data packet can be relayed more quickly than in the related art.

Further, in this embodiment, since the address translator 1 is provided with a plurality of client network connection ports, data packets can be relayed between client computers via the address translator 1.

In the above-described embodiment, the address translation database units are provided at three locations, that is, the IP address translation mechanism 2, the address resolution unit 13, and the address resolution unit 23, and the same contents are managed in all databases. However, it may be integrated as one database for the purpose of saving hardware resources.

[0074]

FIG. 6 shows another embodiment of the present invention.
This will be described with reference to FIG. Although the basic configuration is as described above, the server computer and the address translator 1
We have further devised the case where Ethernet is used to connect to the Internet.

Server Computer and Address Translator 1
When the server computers are connected to each other by Ethernet, and each server computer sends a data packet to another server computer connected to the address translator 1 via Ethernet, it is necessary to recognize the MAC address of the other server computer. In general, a terminal connected to Ethernet uses an ARP (Address Resolution P.P.) from an IP address of a transmission destination to know a MAC address of a transmission destination of a data packet.
rotocol).

In the present invention, each server computer connected to the address translator 1 recognizes its own IP address.
The address is an IP address recognized by another server computer.
Different from P address. For example, in the above-described embodiment,
In the server computer 100, the own IP address recognized by the server computer 100 is 127.
However, in the server computer 200, the IP address of the server computer 100 is 12
7.80.2.2, and the IPs of the server computers 100 recognized by each other are different.

For this reason, in the above-described embodiment, the server computer 100 and the server computer 200
When connected to the address translator 1 via rnet, the server computer 100
If the ARP is used to know the C address, the ARP data packet has a different format from the IP data packet, so that the IP address conversion mechanism 2 cannot convert the IP address. FIG. 7 shows an ARP request data packet and A
4 shows formats of an RP response data packet and an IP data packet. It should be noted that all numerical values in the figure are expressed in hexadecimal.

In another embodiment of the present invention, the address translator 1 of FIG. 1 recognizes an ARP data packet by the address resolution units 13 and 23 belonging to the server connection port and performs ARP processing. Has functions. The paths 14 and 24 from the address resolution units 13 and 23 to the IP address translation mechanism 2 have means for determining whether the data packet is an ARP data packet or an IP data packet. Has a function of converting the destination IP address and the source IP address of the ARP data packet using the address conversion database unit 3. Further, the database managed by the address conversion database unit has a function of storing the MAC address corresponding to each server computer. next,
FIG. 10 shows an example of the address conversion database of this embodiment.

FIG. 6 shows a flowchart of the operation of the address resolution units 13 and 23. Hereinafter, each step of FIG. 6 will be described. Upon receiving the data packet from the data packet receiving units 12 and 22, the address resolution units 13 and 23 read the MAC header of the data packet in step S41. FIG. 7 shows the range of the MAC header.

At step S42, if the received data packet is an ARP request data packet (hereinafter ARP-Req) or an ARP response data packet (hereinafter ARP-Rep), the data packet is further prefetched and the received packet is read. Is ARP-Req. If it is ARP-Req, step S43 is performed. If it is not ARP-Req, it is determined in step S48 whether or not it is ARP-Rep. If it is ARP-Rep, step S49 is performed. ,
The received packet performs the processing of FIG. 4 as an IP data packet.

In step S43, the address translator 1
A pair of a transmission source IP address and a transmission source MAC address is obtained from the received ARP-Req and stored in the address conversion database unit.

In step S44, the address translation database 1 uses the ARP-
A MAC address corresponding to the destination IP address of Req is obtained.

In step S45, if the MAC address of the ARP resolution target server has been registered in the address conversion database unit, step S47 is performed, and if not, step S46 is performed.

In step S46, the physical port to which the server computer to be ARP-solved is connected is determined from the IP address of the server computer to be ARP-solved, using the address translation database unit, and sent to the data packet transmitting unit of that port. Pass ARP-Req. By receiving the ARP-Rep from the server computer, the IP address and the MAC address of the target server computer can be paired, and the MAC address is registered in the address conversion database.

In step S47, ARP-Rep based on the MAC address obtained in step S44 or S46.
ARP- to the data packet transmitter in the same port
Passes Rep and responds to ARP.

In step S49, as in step S43, a pair of the source IP address and the source MAC address is obtained from the ARP-Rep received by the address translator 1, and
It is stored in the address conversion database unit.

Hereinafter, in this embodiment, when the network configuration surrounding the address translator 1 is in the connection configuration shown in FIG. 2, the server computer 100 and the server computer 200 transmit their MAC addresses by ARP.
The operation at the time of finding using will be described.

First, the operation in which the server computer 100 obtains the MAC address of the server computer 200 will be described. ARP-Req cast by server computer 100
Is received by the server connection port 10 of the address translator 1. The ARP-Req determined as a correct data packet by the data packet receiving unit 12 passes to the address resolution unit 13. The address resolution unit 13 reads the MAC header of the received packet in step S41 according to the flowchart of FIG.
Since it is (2), it is determined that the packet is an ARP data packet, and prefetching is further performed.

In step S42, since the data following the MAC header is 000108006040001 (16), it is determined that the data is ARP-Req. In the ARP-Req format shown in FIG. 9, the source MAC address is the MAC address of the server computer 100, and the source IP address is
The IP address of the server computer 100 recognized by the server computer 100 is 127.80.
2.1, and the destination IP address is the IP address of the server computer 200 recognized by the server computer 100.
The address is 127.82.3.

In the step S43, the address translator 1
Of the server computer 100 that recognizes the source MAC address of the ARP-Req received by
It is registered in the address conversion database as a MAC address corresponding to the P address 127.80.2.2.2.

In step S44, the address translator 1
, The destination IP address of the received ARP-Req 127.80.
The MAC address corresponding to 2.3 is searched using the address conversion database unit. However, since the address translation device 1 has not yet registered the MAC address of the server computer 200 in the address translation database, the search in step S44 fails (step S4).
5).

Although the MAC address of the server computer 200 is not registered in the address translation database, it can be seen from the address translation database that the port connected to the server computer 200 is the server connection port 20. Therefore, in step S46,
The ARP-Req is passed to the data packet transmitting unit 21 via the IP address conversion mechanism 2. However, the source IP address is 127.80.2.1 by the IP address conversion mechanism 2.
To 127.80.2.2, the destination IP address is 12
It has been converted from 7.80.2.3 to 127.80.2.1. The source MAC address is the server computer 1
The MAC address of 00 is used as it is.

Server computer 2 that received ARP-Req
00 returns ARP-Rep to the address translation device 1. At this time, in the ARP-Rep format of FIG. 7, the destination MAC address is the MAC address of the server computer 100, the source MAC address is the MAC address of the server computer 200, and the source IP address is recognized by the server computer 200. Address 127.80.2.1 of the server computer 200
And the destination IP address is the server computer 200
Is the IP address 127.80.2.2.2 of the server computer 100 recognized.

After the data packet receiving unit 22 confirms that this ARP-Rep is a correct data packet, the address resolution unit 23 follows the ARP
Perform processing.

When the MAC header is read in step S41, since the last two bytes of the MAC header are 0806 (2), it is determined that the data packet is an ARP data packet, and further prefetching is performed.

In steps S42 and S48,
The data following the MAC header is 00010800060
Since it is 40002 (16), it is determined to be ARP-Rep.

In step S49, the source MAC address of the received ARP-Rep is stored in the address translation database in the server computer 2 which is the source of the ARP-Rep.
M corresponding to IP address 127.80.2.2.3 of 00
Register as an AC address in the address translation database. Here, since the MAC address of the server computer 200 has been obtained, step S46 of the ARP-Req receiving process from the server computer 100 has been completed.

Finally, in step S47, the ARP-Rep received at the server connection port 20 is passed to the data packet transmitting unit 11 via the IP address conversion mechanism 2. However,
The IP address conversion mechanism 2 changes the source IP address from 127.80.2.1 to 127.80.2.3, and the destination IP address from 127.80.2.2 to 127.8.
Converted to 0.2.1. The destination MAC address is the MAC address of the server computer 100, and the source M
The MAC address of the server computer 200 is used as it is for the AC address.

As a result, the server computer 100
The MAC address of the server computer 200 can be known.

Next, the operation in which the server computer 200 obtains the MAC address of the server computer 100 will be described. ARP-Req cast by server computer 200
Is received by the server connection port 20 of the address translator 1. The ARP-Req determined as a correct data packet by the data packet receiving unit 22 passes to the address resolution unit 23. The address resolution unit 23 reads the MAC header of the received packet in step S41 according to the flowchart of FIG.
Since it is (2), it is determined that the packet is an ARP data packet, and prefetching is further performed.

In step S42, since the data following the MAC header is 000108006040001 (16), it is determined that the data is ARP-Req.

In step S44, the destination IP address 12
When the MAC address corresponding to 7.80.2.2 is searched, the ARP-Rep is passed to the data packet transmitting unit 21 because the MAC address of the server computer 100 has already been registered in the address conversion database. However, the destination IP address is the IP address 127.80.2.1 of the server computer 200 recognized by the server computer 200.
And the source IP address is the server computer 2
It is assumed that the IP address of the server computer 100 recognized by 00 is 127.80.2.2.2. The destination MAC address is the MAC address of the server computer 100, and the source MAC address is the MA address of the server computer 200.
The C address is used as it is.

As a result, the server computer 200
The MAC address of the server computer 100 can be known. As described above, by adding means capable of coping with the ARP processing, connection between each server computer and the address translator 1 via Ethernet can be realized with almost no change in the basic configuration of the address translator 1.

[0104]

As described above, according to the network address translation method of the present invention, the following effects can be obtained.

The first effect is that data packets can be quickly relayed between a client and a server in a client-server environment in which the same kind of work is load-balanced by a plurality of server computers. It is in. The reason is that by allocating the same network address to each server, the relay can be performed without converting the network address of the data packet without making the client conscious of which server is communicating.

The second effect is the most common
Even in a client-server environment using Ethernet,
A physical (MAC) address can be resolved while the same network address is assigned to each server. The reason is that an ARP data packet for resolving a MAC address can be recognized and ARP processing can be independently performed.

[Brief description of the drawings]

FIG. 1 is a block diagram of a preferred embodiment of a network address translation system according to the present invention.

FIG. 2 is a network configuration diagram of a network connection device employing the present invention.

FIG. 3 is a flowchart showing an operation of an address resolution unit of a client network connection port shown in FIG. 1;

FIG. 4 is a flowchart showing an operation of an address resolution unit of a server connection port shown in FIG. 1;

FIG. 5 is a flowchart showing the operation of the IP address translation mechanism shown in FIG.

FIG. 6 is a flowchart showing an operation of an address resolution unit of a server connection port shown in FIG. 1;

7A and 7B show examples of data packet formats in the network of the present invention, wherein FIG. 7A shows an ARP_Req format, FIG. 7B shows an ARP_Req format, and FIG. 7C shows an IP data packet format.

FIG. 8 is a diagram showing an example of an address translation database in the embodiment according to the present invention.

FIG. 9 is a diagram showing another example of the address translation database in the embodiment according to the present invention.

FIG. 10 is a diagram showing still another example of the address translation database in the embodiment according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Address translation device 2 IP address translation mechanism 3-5 Address translation database 10, 20 Server connection port 30, 40 Client network connection port 100, 200 Server computer 300, 400 Client network 301, 302, 401, 402 Client computer

Claims (4)

[Claims] 1. A network address translation method for an inter-network connection device for relaying data packets between networks having a plurality of client network connection ports and server connection ports, wherein a destination of the data packets on the network is the server. A means for knowing that the source of the data packet is the server; and a destination network address and a source in the data packet when both the destination and the source of the data packet are the server. A network address conversion method comprising: means for converting a network address; and means for storing a conversion image of the network address. 2. The network address conversion according to claim 1, further comprising means for storing a correspondence between the physical address of the server and the network address, and means for obtaining the physical address from the network address. method. 3. In a network in which the same kind of work is load-shared by a plurality of server computers and performs data packet communication with a plurality of client computers, an IP (Internet Protocol) address of an IP (Internet Protocol) address is provided between the server computers and the client computers. An IP address translation device having a translation function;
A P address translation device, a server connection port of the network, a client network connection port, an IP address translation mechanism for a data packet between the server connection port, and an address translation for storing address translation data for the IP address translation. A network address translation system comprising a database unit. 4. The network address translation method according to claim 3, wherein the same IP address is assigned to the server computer.