JPH0522295A - Bridge device - Google Patents

Abstract

PURPOSE:To implement filtering processing by providing a discrimination means so as to distinguish a packet having a MAC address subject to global management and a packet having a MAC address subject to local management thereby not transferring the packet having the MAC address subject to local management to other LAN. CONSTITUTION:A CPU 11 discriminates whether a MAC address is subject to global management or local management by detecting an address management system designation bit of a MAC address section of a reception packet in a buffer memory 14. As a result, when the MAC address is subject to local management, the reception packet stored in the buffer circuit memory 14 is aborted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent type bridge device for connecting a plurality of LANs (local area networks) to each other.

[0002]

2. Description of the Related Art Conventionally, a bridge device of this type, which connects a plurality of LANs to each other, receives all packets flowing on the LAN, and separates each received packet with another L packet.
A process called filtering for determining whether to transfer to the AN is performed. Further, the bridge device sends the received packet, which is determined to be transferred to another LAN by this filtering process, to the corresponding LAN. By the way, the bridge device uses the MAC of the received packet.
(Media Access Control) A transfer data base storing direction data for specifying the LAN to which this packet is to be sent is provided with the address as a key. Therefore, the bridge device searches the transfer database using the destination MAC address of the received packet as a key and obtains the direction information of the LAN in which the destination station exists. The filtering process for determining

FIG. 4 shows an L equipped with the conventional bridge device.
It is the figure which showed the prior art example of AN communication system. The bridge device 1 is connected to LAN I, B, and C. Each LAN
There are multiple stations a-1, a-2, ...
B-1, b-2 ..., c-1, c-2 ..., and so on. When the bridge device 1 receives a packet from, for example, a LAN and determines that the destination station specified by the MAC address of the packet is on the LAN, for example, it sends the received packet to the LAN. ..

Here, the contents of the transfer database provided in the above-mentioned bridge device 1 are set by the administrator and from the address of the receiving source when the bridge device 1 receives the packet. There is a case where the station that transmitted the packet learns the direction information of the LAN to which the station is connected and automatically registers the information, and there are those that have both of these setting methods and bridge apparatuses that have one of these setting methods. ..
The MAC address used as the filtering judgment information has two management methods, local management and global management. In the former case, it is locally assigned by the system administrator in a certain system. The MAC address is shown, and in the latter case, it is the only MAC address in the world.

However, in the conventional bridge device, filtering processing is performed without distinguishing the above two types of MAC addresses. Therefore, in the LAN communication system as shown in FIG. 4, since the locally managed MAC address is assigned for each system, there is a possibility that an address having the same value exists in a plurality of LANs. LAN for example
Station a of ai and station of a LAN ro
It happens that 2 have the same MAC address. In such a case, the above-mentioned bridge device 1 sends the received packet to a LAN that should not be sent. If such a situation occurs, it adversely affects the communication system, and in some cases, the system. There is also the possibility that an accident will occur that will be down.

[0006]

As described above, the conventional bridge device does not perform filtering processing by discriminating between the locally managed MAC address and the globally managed MAC address. If there are two or more stations having a managed MAC address in one communication system, the received packet having the MAC address will be sent to the LAN where it should not be sent, which may adversely affect the communication system. Far from affecting it, there was a drawback that an accident that the communication system went down depending on the case.

Therefore, the present invention eliminates the above-mentioned drawbacks by distinguishing a packet having a globally managed MAC address from a packet having a locally managed MAC address and performing local management. It is an object of the present invention to provide a bridge device capable of performing a filtering process that does not transfer a packet having a different MAC address to another LAN.

[0008]

According to the present invention, there is provided a bridge device having a filtering processing function for judging whether or not a packet received from a LAN is transferred to another LAN based on the MAC address of the packet. A determination unit that determines whether the MAC address is globally managed or locally managed by referring to the address designation management method designation bit of the received packet, and the received packet is determined by the determination unit. Only when it is determined that the received packet has a globally managed MAC address, a control means for performing the filtering process on the received packet is provided.

[0009]

In the bridge device of the present invention, the judging means refers to the address designation management method designation bit of the received packet to determine whether the MAC address of the received packet is globally managed or locally managed. To judge. The control unit applies the filtering process to the received packet only when the determination unit determines that the received packet has the globally managed MAC address.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the bridge device of the present invention. Reference numeral 11 is a CPU that performs individual control such as filtering processing and packet transfer processing, and control of the entire apparatus. Reference numeral 12 is a MAC address and direction information of the LAN in which a station having this address exists (LAN
(Corresponding to the position of the port to which is connected) is stored in the transfer database, 13 is a MAC controller for transmitting / receiving packets to / from the LAN 17 in the MAC layer and below,
Reference numeral 14 is a buffer memory for temporarily holding the received packet, and 15 is a MA for transmitting / receiving the packet to / from the LAN 18.
A MAC controller performed in the layer C and below, 16 is a bus connecting the above-mentioned functional blocks, and 17 and 18 are LANs connected to the above-mentioned bridge device.

Here, the CPU 11 constitutes a judgment means and a control means.

Next, the operation of this embodiment will be described. For example, when the MAC controller 13 receives a packet on the LAN 17, it stores it in the buffer memory 14.
Similarly, when the MAC controller 15 receives a packet on the LAN 18, the MAC controller 15 stores the packet in the buffer memory 14. When the CPU 11 is informed of the reception of the packet by a means such as an interrupt, the flow chart shown in FIG.
Perform processing according to

First, in step 201, the CPU 11 refers to the MAC address portion of the received packet in the buffer memory 14 as shown in FIG. 3, and in particular, detects the address management method designating bit 31 shown in FIG. Step two
At 02, it is determined whether the MAC address is globally managed or locally managed. Here, if the address management method designation bit 31 shown in FIG. 3 is "0", the globally managed MAC is used.
An address is indicated, and if it is "1", it indicates that the MAC address is locally managed. When it is determined in step 202 that the MAC address of the received packet is locally managed, the process proceeds to step 206, and the received packet stored in the buffer memory 4 is discarded. On the other hand, if it is determined in step 202 that the MAC address of the received packet is globally managed, the process proceeds to step 203, and the transfer database 2 is searched using the MAC address of the received packet as a key. , LAN where the destination station exists
Get direction information. As a result, it is determined whether or not the packet received in step 204 is to be transferred. If the packet is not transferred, the process proceeds to step 206. If the packet is transferred, the process proceeds to step 2
Go to 05. Here, the processing of step 204 will be specifically described. If the received packet is obtained from the LAN 17 and the destination station is on the LAN 18, it is determined that the packet is to be transferred, and if it is on the LAN 17, the packet is transferred. Determine what. In step 205, the received packet read from the buffer memory 14 is MAC-controlled.
LAN 13 (or MAC controller 15) to LAN 17
(Or the LAN 18) and then the transfer process is performed and the process is terminated.

According to the present embodiment, the MAC address of the packet received by referring to the address management method designating bit 31 of the received packet is either globally managed or locally managed. If the received packet is locally managed, the received packet is transferred to the LAN where it should not be transferred in order to discard the received packet and prevent the processing from being transferred to the LAN. It is possible to prevent such a situation, and it is possible to improve the reliability of the communication system. In the above embodiment, the address management method of the received packet (distinguishing between global management and local management) is performed by the processing of the CPU 11, but this is performed by the MAC controller 13, 1.
The same effect can be obtained by the process of No. 5.

[0015]

As described above, according to the bridge device of the present invention, a packet having a globally-managed MAC address and a packet having a locally-managed MAC address are distinguished from each other, and local It is possible to perform a filtering process that does not transfer a packet having a managed MAC address to another LAN.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a bridge device of the present invention.

FIG. 2 is a flowchart showing a filtering process of the CPU shown in FIG.

3 is a diagram showing an example of a format of a MAC address of a packet received by the device shown in FIG.

FIG. 4 is a diagram showing an example of a conventional LAN communication system.

[Explanation of symbols]

11 ... CPU 12 ... Transfer database 13 and 15 ... MAC controller 14 ... Buffer memory

Claims (1)

Claim: What is claimed is: 1. A bridge device having a filtering function for determining whether or not to transfer this packet to another LAN based on the MAC address of the packet received from the LAN. Determining means for determining whether the MAC address is globally managed or locally managed by referring to the addressing management method designating bit of the received packet; Managed MA
A bridge device comprising: a control unit that performs the filtering process on the received packet only when it is determined that the received packet has a C address.