JP2000332776A - Computer with communication interface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a computer that can easily attain load distribution and degenerated operation, in the case that a plurality of physical interfaces are present in the computer. SOLUTION: This computer is provided with an address conversion section 12 provided at the low-order position of an IP module, having a logical IP address and with a plurality of physical address interfaces 141-144 each having a physical address. The address conversion section 12 converts the logical IP addresses of a sender and a destination into physical IP addresses at packet transmission, records the addresses and inversely converts the physical IP addresses into the logical IP addresses, when receiving a packet on the basis of the recorded information so as to make the logical addresses used by the physical address interfaces 141-144 independent of the physical addresses which are actually used for communication.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a computer having a communication interface that realizes multiplexing of communication paths, improvement of reliability by a redundant configuration, and load distribution among a plurality of interfaces.

[0002]

2. Description of the Related Art In order to improve the reliability of a computer system, a high-availability system has been proposed which multiplexes using a plurality of network interfaces and networks and prepares a plurality of computers having the same configuration to form a cluster. Have been. Generally, in such a high-availability system, a logical IP address is set in addition to the IP address of the physical interface, and the application uses this logical IP address as a destination address to switch the computer or switch the interface. Conceal the effects of

[0003] For assigning a logical IP address, a logical IP address adding function supported by the OS is used.
This is realized by changing the actual IP address of the physical interface to a logical IP address and restarting the system.

[0004]

In such a high-availability system, if the network ID of the logical IP address is different from the network ID of the physical IP address, the computer operates as a router, broadcasts routing information, and performs internal routing. Route control is performed.

Normally, a route control function using static routing with a fixed route or dynamic routing such as "RIP" is used for route control of IP packets. In packet transmission, a route with the lowest communication cost is always selected even if there are a plurality of communication interfaces, and load distribution cannot be realized due to the nature of the IP route control mechanism. Further, from the viewpoint of stabilizing the path control, the path switching is designed to have a relatively long timeout time, and the path switching may not be performed in a short time. If the network address of the logical IP address matches the network address of the physical IP address, the route control within the computer is not performed, but the ARP (Address Resolution Protocol)
ocol) Due to the presence of the cache, there is a problem that load balancing and failure avoidance do not function sufficiently.

According to the present invention, by associating a logical IP address with a physical IP address by using an address translation mechanism, it is not affected by path control or an ARP cache, and can be easily loaded when a plurality of physical interfaces exist. The purpose of the present invention is to provide a computer capable of performing decentralized and degenerate operations.

[0007]

The present invention comprises a network address translation unit provided below an IP module having a logical IP address, and a plurality of physical address interfaces having physical addresses. The unit converts a logical IP address to a physical IP address when transmitting a packet, and converts a physical IP address when receiving a packet.
Provided is a computer characterized by performing a reverse conversion from a P address to a logical IP address to make a physical address used in a physical address interface and a logical IP address actually used for communication independent.

According to the present invention, in a computer having a communication interface having independent physical IP addresses, a network address translator provided below an IP module having a logical IP address, and a plurality of physical addresses having physical addresses A network address translation unit that translates the source and destination logical IP addresses into physical IP addresses at the time of packet transmission, records the addresses, and from the recorded information from the physical IP address at the time of packet reception. There is provided a computer characterized in that a physical address used in the physical address interface and a logical IP address actually used for communication are made independent by performing reverse conversion to a logical IP address.

According to the present invention, a plurality of physical interfaces and a network address translation (NAT) layer for performing address translation below the IP protocol module are provided. The physical interface of the transmission source is selected according to the state, the physical IP address which is actually the destination address of the packet is obtained from the logical IP address of the transmission destination, and the destination and the transmission source address of the packet to be transmitted are changed using these address information. I do. The source and destination addresses are determined by the load status of each interface, the status of the network used, and the operating status of the partner interface. Each physical interface has a management module, which periodically checks the load information of the interface, the operation status of the destination interface, and the information of the network. As a result, a communication is realized in which a completely different address from the logical IP address specified by the application is used, and load distribution and degeneration when a failure occurs are automatically performed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the device according to the present invention will be described below with reference to the drawings.

According to the computer system shown in FIG.
A TCP / IP protocol stack 11 is connected to a network address translation unit, that is, a NAT unit 12. TCP
The / IP protocol stack 11 has an IP layer for processing IP packets, and this IP layer holds logical IP addresses. Network address translator, ie NAT
The unit 12 converts the destination and the source address of the transmitted and received IP packet based on a predetermined rule. It also manages the load status and communication status of each interface.

[0012] Address conversion table in the NAT section 12 (address translation database) 13 and a plurality of physical addresses interface 14 ₁ to 14 ₄ are connected. The address translation table 13 has a translation table used at the time of address translation performed by the NAT unit 12. In this conversion table, as shown in FIG. 2, the own IP address (logical IP address) and the converted IP address (physical IP address) are described in association with each other. It is used to reverse translate the translated IP address of a packet sent from the other party to the translated IP address. That is, the NAT unit 12 refers to the address conversion table 13 and refers to the logic I of the TCP / IP protocol stack 11.
Physical address interface 14 ₁ P-address to be translated into a physical IP address assigned respectively to 14 _4. In this conversion, the NAT unit 12 always manages to which physical IP address the logical IP address has been converted.

A packet is sent from the TCP / IP protocol stack 11 to the NAT unit 12 in the form of an Ethernet packet as shown in FIG. This Ethernet packet has a header H and a MAC address (destination address D).
A and a source address SA);
It has a data part DATA and a CRC part. The IP packet handled in the present embodiment is provided in the data section DATA and has a destination address DA and a source address SA. The NAT unit 12 converts the source address SA of this IP packet into a physical address and
4 ₁ to assign to 14 _4. That is, the address conversion is performed on the source address SA of the IP packet.
The translation target address is the source address SA of the IP packet.
Alternatively, the destination address DA may be converted to a physical address.

In the computer having the communication interface having the above configuration, when transmitting the IP packet of the Ethernet packet shown in FIG. 3 from the TCP / IP protocol stack 11 to the partner computer, the NAT unit 12 executes the address conversion table 13. Refer to the destination logical IP
A physical IP address to be actually transmitted is selected from the addresses and set as a destination IP address. Further, from the state of the network interface 14 ₁ to 14 _4, select the small interface for effective load, performs address translation for the packet physical IP address with the the interface as the source IP address, performs the transmission of packets.

When a packet is received, the destination IP address and the logical IP address of the transmission source are obtained from the record of the address conversion table 13 and the physical IP address of the received packet, the address conversion of the received packet is performed, and the upper layer is notified. When performing the address conversion, the packet is reconfigured not only by simply replacing the address but also by recalculating up to the IP header checksum. At this time, the contents of the payload of the IP packet are not changed.

[0016] In the NAT unit 12, to the network interface 14 ₁ manages the state of 14 ₄ records the load situation. Alternatively, it is acceptable to check the continuity due ping command with the regular communication partner network interface, to the network interface 14 ₁ used to determine the material of the case of selecting the 14 _4. In the normal state, load distribution is performed, but if an abnormality is detected during periodic conduction confirmation, a retry is performed with predetermined contents. It records and then automatically degenerates the network interface without using it.

For a communication partner having a similar address translation mechanism, the correspondence between the physical IP address and the logical IP address is registered in a database in advance, so that
Address conversion can be performed in both directions.

When communicating with a computer having no ordinary address translation mechanism, packets are received by performing proxy ARP (proxy address resolution protocol) for the logical IP address at each network interface.

When transmitting a packet, the address translation table 13 is searched. If the address is not a translation target address, no translation is performed, and the logical IP address is used as a source address.

Next, the processing performed by the NAT unit 12 will be described with reference to FIG.

First, whether transmission or reception is confirmed (S1),
In the case of transmission, an IP packet is received (S2). Next, an optimal interface, for example, a vacant interface based on statistical processing is selected (S3). At this time, it is confirmed whether or not the IP address has already been translated by referring to the address translation table 13 (S4). If it has been translated, the translated physical address is used (S
5). If not translated, the logical IP address is translated into a physical address and assigned to the selected interface (S8). Thereafter, the packet is transferred to the interface.

When the reception is set in step S1, the physical address of the interface is inversely converted and returned to the original logical address (S7). Thereafter, the packet is transferred to a higher order (S9).

As described above, according to the present invention, the logical IP address of the upper module is assigned to the NA provided in the lower layer.
The data is converted into a physical address by the T unit and assigned to a lower interface. This realizes communication in which load distribution and degeneration when a failure occurs are automatically performed.

In the above embodiment, an example in which a plurality of interfaces are connected to one computer has been described. However, a similar mechanism can be applied to a case where a plurality of computers share one logical IP.

[0025]

According to the present invention, the user application is the logic I of the partner.
By simply executing the application while paying attention only to the P address, it is possible to use the load distribution and the degeneration function at the time of failure.

[Brief description of the drawings]

FIG. 1 is a block diagram of a computer having a communication interface according to an embodiment of the present invention.

FIG. 2 is a view showing a format of an address conversion table shown in FIG. 1;

FIG. 3 is a diagram showing a format of an Ethernet packet.

FIG. 4 is a flowchart illustrating an address translation process of a network address translation unit.

[Explanation of symbols]

11 ... TCP / IP protocol stack 12 ... network address conversion unit 13 ... address conversion table 14 _1-14 4 _... Interface

Claims (2)

[Claims] 1. A computer having a communication function, comprising: a network address translator provided below an IP module having a logical IP address; and a plurality of physical address interfaces having physical addresses. Converts a logical IP address to a physical IP address when transmitting a packet, performs reverse conversion from a physical IP address to a logical IP address when receiving a packet, and actually uses the physical IP address for communication with the physical address used in the physical address interface. Logical IP
A computer characterized by independent addresses. 2. A computer having a communication function, comprising: a network address translation unit provided below an IP module having a logical IP address; and a plurality of physical address interfaces having a physical address. Converting the source and destination logical IP addresses into physical IP addresses at the time of packet transmission, recording the addresses, and performing reverse conversion from the physical IP address to the logical IP address at the time of packet reception from the recorded information;
A computer wherein the physical address used in the physical address interface and the logical IP address actually used for communication are made independent.