JPH0556050A - Network system - Google Patents

Abstract

PURPOSE:To improve the communication performance by releasing a data processing terminal equipment from the processing of an ARP response so as to relieve the load of the terminal equipment. CONSTITUTION:The cross reference between an IP address of data processing terminal equipments 11-14 subscribing the network and a MAC address is managed on an address table 24 of a network equipment 20. The network equipment 20 replies a collation request of the MAC address. Thus, each of the data processing terminal equipments 11-14 is relieved from the reply processing of the MAC address thereby relieving the load of the data processing terminal equipments 11-14.

Description

Detailed Description of the Invention

[0001]

This invention relates to a server, a bridge,
The present invention relates to a network system in which a network device such as a router or a gateway and a plurality of data processing terminals such as a workstation are combined.

[0002]

2. Description of the Related Art Generally, in a network system such as a LAN, in order for each data processing terminal such as a workstation or a minicomputer to perform communication such as file transfer with a partner data processing terminal, the partner data processing terminal is required. It is necessary to know not only the protocol address at the network layer level but also the hardware address at the data link layer level.

For example, TCP / I using Ethernet
In communication such as P, the packet actually transmitted on the network is an IP (Internet) at the network layer level.
netProtocol) MA whose address is Ethernet level
It is replaced with a C (Media Access Control) address.

However, it is very inconvenient for the user to manage the MAC addresses of other terminals in each data processing terminal. Therefore, each data processing terminal normally manages only the IP address of the other terminal, and does not manage the MAC address of the other terminal.

A method for obtaining a MAC address from an IP address is address resolution (ARP; Addre).
A process called ss Resolution Protocol) is often used. The process of recognizing a MAC address using this address resolution is performed as follows.

That is, first, the source data processing terminal, which does not know the MAC address of the destination data processing device, transmits a broadcast packet including the destination IP address. This broadcast packet is captured by all other data processing terminals in the network system. Then, the data processing terminal having the same IP address as the IP address specified by the broadcast packet is an ARP including the MAC address of its own device.
The response packet is transmitted to the transmission source terminal of the broadcast packet. Thereby, the data processing terminal of the transmission source can recognize the MAC address of the transmission destination.

The MAC address of the destination once obtained by this address resolution process is stored in an internal table or the like of the data processing terminal. Therefore, only in the case of communication with a party not registered in this table,
The address resolution process described above is performed.

However, in the address resolution process in each data processing terminal as described above, it is necessary to return the ARP response on the data processing terminal side, which causes a problem that the load on the data processing terminal is increased. The increase in load on such a data processing terminal is
This causes an overhead in software processing in the terminal, which is a major cause of deterioration in communication performance of the entire network system.

Further, as described above, the AR is provided to each data processing terminal.
If the P-response function is provided, it is difficult to manage addresses throughout the system. For example, there is a risk that the same IP address will be given twice due to a mistake made by the network administrator, resulting in communication failure. It was

[0010]

Conventionally, the data processing terminal has to make an ARP response, which increases the load on the terminal and deteriorates the communication performance of the entire system.

The present invention has been made in view of the above circumstances, and provides a network system having sufficiently high communication performance by allowing a data processing terminal to be released from processing an ARP response and reducing the load on the terminal. The purpose is to do.

[0012]

Means and Actions for Solving the Problems
In a network system including a network device and a plurality of data processing terminals coupled to each other, the correspondence between the network layer level protocol address and the data link layer level hardware address of each of the data processing terminals is registered in the network device. Address storage means, and receives a hardware address inquiry request of a partner data processing terminal issued from each of the data processing terminals,
A means for obtaining a hardware address corresponding to a protocol address of a destination data processing terminal designated by the inquiry request by referring to the address storage means, and a destination for the data processing terminal issuing the inquiry request Means for notifying the protocol address of the data processing terminal, and a response to the inquiry request is executed by the network device.

In this network system, the correspondence between the protocol address and the hardware address of the data processing terminal that has joined the network system is managed by the network device. The device responds. Therefore, each data processing terminal can be released from the response processing of its hardware address, and the load on the data processing terminal can be reduced. In addition, since the protocol address of each terminal can be collectively managed by the network device, it is easy to prevent a communication failure due to the assignment of a duplicate address, etc., and the reliability of the network system can be improved.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a network system according to an embodiment of the present invention. This network system includes data processing terminals 11 to 14 connected to a LAN segment 10 and a network device 20.

The data processing terminals 11 to 14 are realized by workstations, personal computers, minicomputers, etc., and communicate with each other via the LAN segment 10 and via the network device 20. Other LA not shown connected
It communicates with other data processing terminals that are subscribing to N segment, WAN, public network, etc.

The network device 20 constitutes, for example, a network server, a repeater, a bridge, a router, a gateway, or the like, and is used to connect the LAN segment 10 to another LAN segment, WAN, public network, or the like. used. This network device 2
0 receives all the packets on the LAN segment 10 and other connected networks (not shown) in the promiscuous mode, and executes the data transfer service, the address resolution (ARP) response service, and the like.

The network device 20 has a plurality of ports, one of which is connected to the LAN segment 10. The network interface for the LAN segment 10 is composed of a local bus 21, a CPU 22, a buffer memory 23, an address table 24, a communication controller 25, and a transceiver 26, as shown in the figure. The CPU 22, the buffer memory 23, the address table 24, and the communication controller 25 are interconnected via the local bus 21, and the communication controller 25 is connected to the LAN segment 10 via the transceiver 26.

The local bus 21 is used by the CPU 21 to access the buffer memory 22, the address table 24, the communication controller 25, and the like. The buffer memory 23 stores transmission / reception data for data transfer performed via the network device 20.

The address table 23 is used by the network device 20 to execute the response service of the address resolution (ARP). As shown in FIG. The correspondence between the protocol address (IP address) at the network layer level of the data processing terminals 11 to 14 and the hardware address (MAC address) at the data link layer level such as the MAC level is registered.
In FIG. 2, data processing terminals 11, 12, 13, 1
4 IP addresses are "A", "B", "C",
"D", and the data processing terminals 11, 12, 13, 14
MAC addresses are "A '", "B'", and "C", respectively.
It is assumed that they are "" and "D".

The CPU 4 controls the entire network device 20, and executes data transfer control and address resolution (ARP) response processing using the address table 23.

The communication controller 25 receives packets from the LAN segment 10 and the buffer memory 2
The data in 3 is packetized and transmitted to the LAN segment 10. The communication transceiver 26 sends and receives packets to and from the network.

In the address resolution process, for example, the data processing terminal 11 issues a broadcast packet P1 containing the IP address "B" of the data processing terminal 12. This broadcast packet P
Upon receipt of 1, the network device 20 refers to the address table 24 and refers to the M address corresponding to the IP address “B”.
Search for the AC address "B '" and find its MAC address "B"
The ARP response packet P2 including "" is transmitted to the data processing terminal 11.

In this way, the data processing terminal 11 makes the MAC address "B" of the data processing terminal 12 of the communication partner.
After recognizing “′”, the data processing terminal 11 transmits the packet P3 having the MAC address “B ′” as the destination address to the data processing terminal 12, and the data processing terminal 1
2 to the data processing terminal 11 the MAC address "A '"
A packet P4 whose destination address is P is transmitted, whereby communication between the terminals 11 and 12 is executed.

The communication controller 25 receives packets from the LAN segment 10 and the buffer memory 2
The data in 3 is packetized and transmitted to the LAN segment 10. The communication transceiver 26 sends and receives packets to and from the network.

Next, with reference to the flowchart of FIG. 3 and the frame structure of FIG. 4, the operation from the reception of the packet by the network device 20 to the transmission of the packet for notifying the MAC address will be described.

All packets issued from the data processing terminals 11 to 14 are received by the network device 20. In this case, in the network device 20, the received packet is directly stored in the buffer memory 23 by the DMA function of the communication controller 25 (step S1).
1). The CPU 22 refers to the destination MAC address of the received packet and determines whether it is addressed to its own node (step S12).

In the case of a packet addressed to its own node, the CPU 2
2 executes a normal process for a packet addressed to its own node based on a predetermined algorithm determined by which of the network device 20 implements a server, a repeater, a bridge, a router, or a gateway (step S13). ).

If the packet is not addressed to its own node, C
In the PU 22, the destination MAC address of the received packet is M
It is checked whether or not it is a broadcast address for inquiry of an AC address (for example, an address of all bits 1) (step S14).

When the address is not the broadcast address, the CPU 22 discards the packet when the network device 20 is a dedicated server for making an ARP response, and the network device 20 connects to a network such as a bridge or a router. If it is to perform the above, the transfer to another network or the discard is performed according to a predetermined transfer algorithm. For example, when the network device 20 is a bridge or a router, when the destination address of the packet received from the LAN segment 10 via the first port specifies the terminal connected to the LAN segment 10, the data via another port is used. It is discarded because it does not need to be transferred, and when the destination address designates a terminal connected to another network, the received packet is transferred via the port corresponding to the network to which the terminal belongs. The transfer of such packets is usually controlled using a well-known transfer address table called a transfer database.

The destination MAC address of the received packet is MA
If it is the broadcast address for the C address inquiry, the CPU 22 causes the address table 24
Is checked to see if the destination IP address included in the received packet is registered in the table 24 (steps S16 and S17).

If not registered, the CPU 22
Raises an alarm when the network device 20 is functioning as a network server and notifies the network administrator that an ARP response cannot be made. When the network device 20 is a bridge or router, the connection is established. The received packet is broadcast-transferred to all other networks not shown (step S18).

This is because the ARP response is transmitted to the data processing terminal or the network device 2 existing in another network.
This is because it is obtained from a bridge or router having the same function as 0.

On the other hand, if the destination IP address included in the received packet is registered in the table 24, C
The PU 22 reads the MAC address corresponding to the destination IP address, and sends an ARP response packet including the MAC address as the source MAC address to the LAN segment 10 (step S19). This ARP response packet is received by the terminal that issued the broadcast packet, and the MAC address of the communication partner is recognized thereby. Next, with reference to FIG. 4, a frame structure of a packet transmitted / received in such an ARP response process by the network device 20 will be described.

For example, when the data processing terminal 11 issues a broadcast packet P1 inquiring about the MAC address of the data processing terminal 12 which is a communication partner, the packet P1 is as shown in FIG. 4 (A). Includes "11111 ..." Indicating broadcast as the destination MAC address DA (MAC),
The C address SA (MAC) includes the MAC address "A '" of the data processing terminal 11, the destination IP address includes the IP address "B" of the data processing terminal 12, and the source IP address of the data processing terminal 11 is the IP address. Contains "A".

In this case, the CPU 22 sends the packet P
The MAC address "B '" corresponding to the destination IP address "B" of No. 1 is obtained from the address table 24, and the MAC address "B'" shown in FIG.
The ARP response packet P2 as shown in FIG. The ARP response packet P2 includes "A '" indicating the source terminal 11 of the broadcast packet as the destination MAC address DA (MAC), and the destination terminal 12 obtained from the address table 24 as the source MAC address SA (MAC). MAC address of "B
″ ”, The IP address“ A ”of the terminal 11 as the destination IP address, and the terminal 1 as the source IP address.
2 IP address “B” is included.

The data processing terminal 11 receives the ARP response packet P2, and sends the source MA of the packet P2.
Address "B '" included in C address SA (MAC)
Is recognized as the MAC address of the communication destination terminal 12. After this, the data processing terminal 11 to the data processing terminal 1
2 includes the destination MAC as shown in FIG.
The packet P3 including the address “B ′” is transmitted as the address DA (MAC), and the data processing terminal 12 sends to the data processing terminal 11 the destination MAC address DA (MAC) as shown in FIG. 4D. ), The packet P4 including the address "A '" is transmitted, whereby the communication between the terminals 11 and 12 is executed.

Next, a case where a terminal having a different ARP method is operated in the LAN segment 10 will be described. Here, as an example thereof, a case will be described in which a terminal 50 that responds to ARP is additionally connected to the LAN segment 10 as shown by a broken line in FIG.

In response to a MAC address inquiry from the terminal 50 to another terminal, the network device 20 returns a response, so that no problem occurs. However, when a MAC address is inquired from the other terminals 11 to 14 to the terminal 50, both the network device 20 and the terminal 50 return a response on the inquiring side.
In this case, in order to prevent the occurrence of communication failure, the network device 20 is provided with a mechanism that does not statically return a response to the inquiry about the MAC address to the terminal 50, or the terminal that receives the ARP response. It is preferable that one side ignores one response or starts communication only when two MAC addresses are compared and they match.

As described above, in the network system of this embodiment, the correspondence between the IP address and the MAC address of the data processing terminals 11 to 14 that join the network corresponds to the address table 24 of the network device 20.
It is managed above, and the network device 20 responds to the inquiry request of the MAC address. Therefore, each of the data processing terminals 11 to 14 is
The response processing of the C address can be released, and the load on the data processing terminals 11 to 14 can be reduced.

Further, since the IP address of each of the terminals 11 to 15 can be collectively managed by the network device 20, it becomes easy to prevent the occurrence of a communication failure due to the assignment of the duplicate address to the terminals and improve the reliability of the network system. be able to.

The network device 20 of the present invention is
Originally, as long as all the packets on the network are received in the promiscuous mode, they can be applied to all devices such as servers, bridges, routers, repeaters, and gateways.

In this embodiment, the system in which the CPU 22 refers to the address of the received packet by software processing has been described. For example, the communication controller 2
5 is provided with a cyst register or the like, and the destination IP address of the received packet latched in the cyst register is set to the terminal 11
~ 14 IP address sequentially compared by hardware,
It is also possible to obtain the MAC address of the communication partner according to the comparison result.

Further, in this embodiment, in order to simplify the explanation, the address entry in the address table 24 is set to the static method, but the learning method which is already well known in the entry method to the transfer database such as a bridge. Addresses can be dynamically registered in the address table 24 by using the function. In this case, the network device 20 registers the source MAC address and the source IP address included in the received packet in the address table 24 every time the packet is received, and the packet is stored even if a predetermined time has elapsed. If there is no inquiry about the MAC address for the registered address, the entry is deleted from the table 24. By doing this, memory resources can be effectively used,
The address table 24 having a small storage capacity can realize ARP responses for many terminals.

However, at this time, even if the communication destination terminal is connected to the LAN segment 10 when the broadcast packet is received, the IP of the communication destination terminal is received.
There may be a case where the address does not exist in the address table 24. In this case, a third unique address is prepared, the network device 20 is provided with a function of adding the unique address to a broadcast packet and then transmitted, and each terminal is provided with the third unique address. It is possible to notify the sender of the MAC address of the other party by providing a function of making an ARP response only to the broadcast packet that has been sent.

[0046]

As described above, according to the present invention, the data processing terminal can be released from the processing of the ARP response, and by reducing the load on the terminal, a network system having sufficiently high communication performance can be realized. ..

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a network system according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of contents of an address table managed by a network device of the network system shown in FIG.

3 is a flowchart illustrating ARP response processing of the network system of FIG.

FIG. 4 is a diagram showing an example of contents of a packet transmitted / received in an ARP response process of the network system of FIG. 1.

[Explanation of symbols]

10 ... LAN segment, 11-14 ... Terminal, 20 ... Network device, 22 ... CPU, 23 ... Buffer memory, 24 ... Address table, 25 ... Communication controller.

Claims (1)

[Claims] 1. A network system in which a network device and a plurality of data processing terminals are coupled to each other, wherein the network device includes a network layer level protocol address and a data link layer level hardware address of each of the data processing terminals. The address storage means in which the correspondence is registered and the inquiry request for the hardware address of the partner data processing terminal issued from each of the data processing terminals are received, and the inquiry request is designated by referring to the address storage means. A means for obtaining a hardware address corresponding to the protocol address of the destination data processing terminal, and means for notifying the data processing terminal that issued the inquiry request of the protocol address of the destination data processing terminal, The response to the inquiry request is sent to the network Network system and executes the device.