JPH07288541A - Address filtering method for connection device - Google Patents

Abstract

PURPOSE:To reduce the frequency of execution of filtering by an MPU without increasing the manufacturing cost. CONSTITUTION:When a CAM 15 is not fully occupied, a control section 21 being a local hardware implements address filtering processing by using a destination address not through an MPU 22, and when the CAM 15 is fully occupied, the control section 21 implements address filtering processing based on a sender address and a destination address, and the MPU 22 takes over the address filtering processing by using a RAM 23 as to only the frame whose relay is discriminated to be required.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an address filtering method for a connection device connected between a plurality of communication networks, for example, LAN (local area network).

[0002]

2. Description of the Related Art Conventionally, in this type of bridge device, a destination address of a frame received from an arbitrary LAN line,
By comparing and collating with the source address group of the frame previously received from the LAN line, and as a result, when the two addresses match, the relaying process of the newly received frame is interrupted, which is wasteful. There was a function to prevent a decrease in line efficiency due to data.

This function is performed by a program-controlled MPU.
It was executed by the processing operation of the (processing device), but recently, it has come to be processed by hardware using a CAM (associative storage device) for the purpose of reducing the load of the MPU or improving the relay processing speed. It was Such a bridge device is disclosed in, for example, Japanese Patent Laid-Open No. 5-153125, and in the above device, the address comparison and collation of the relay frame is performed without passing through the MPU. Had been discarded.

[0004]

However, in the above-mentioned bridge device, in order to perform complete filtering, the capacity of the CAM to be implemented is registered as the number of terminal stations connected to the system or as a filtering target. It must be sufficient for the number of source addresses that will be sent. Therefore, in the bridge device, the C
There is a problem that the manufacturing cost increases in proportion to the capacity of the AM. In addition, if the capacity of the CAM is not sufficient for complete filtering, there is a problem that filtering is omitted, that is, line efficiency is reduced due to useless frame relay.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an address filtering method for a connection device that can reduce the frequency of execution of filtering performed by the MPU without increasing the manufacturing cost.

[0006]

In order to achieve the above object, according to the present invention, when a relay frame is received, the destination address of the relay frame is detected by a received frame address detecting section which is an address detecting means, and the address is detected. The control unit of the control unit searches for whether or not it is registered in the CAM that is the installed first storage unit. If not registered, the source address of the relay frame is registered in the first storage unit. In the address filtering method of the connection device in which the relay processing is performed by the MPU which is the processing means and when the relay processing is registered by the control unit and the abort generation unit, the number of the registered source addresses A monitoring step of monitoring by the control unit whether the storage capacity of the CAM is exceeded, and when the number of the source addresses exceeds the storage capacity. A detecting step of detecting a source address and a destination address of the received relay frame by the address detection section, and a control section searching whether the detected source address and destination address are registered in the CAM; And a discarding step of discarding the relay frame in the control unit and the abort generating unit when both the source address and the destination address are registered, and at least one of the source address and the destination address is unresolved. In the case of registration, the MPU registers the source address in the RAM, which is the second storage means to be installed, and a second searching step for searching whether the destination address is registered in the RAM; When the destination address is registered in the second search step, the MPU does not perform the relay processing of the relay frame, and the destination address is registered. If this address is not registered, the address filtering process of the connection device comprising a processing step of performing a relay processing of the relay frame MPU is provided.

[0007]

[Function] When the filtering load is high immediately after the start of operation, the control unit, which is local hardware, performs the address filtering process without going through the MPU,
When the number of registered addresses exceeds the storage capacity of the installed CAM, the MPU that has recognized the full storage capacity takes over the address filtering process. The address filtering process by the MPU is executed only for the frame of which the reception is notified as a result of filtering by the control unit.

Therefore, it is possible to prevent omission of address filtering, reduce the processing load of the MPU, and reduce the frequency of execution of filtering performed by the MPU.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An address filtering method for a connecting device according to the present invention will be described with reference to the drawing of FIG. FIG. 1 is a block diagram showing the configuration of a connection device using the above address filtering method. In the figure, the connection device is a line transceiver 11 connected to a LAN line (not shown).
A received frame address detection unit 12 connected to the line transceiver 11, an address data buffer 13 for storing address data, and a C for performing a CAM memory operation.
AM memory interface unit (hereinafter referred to as "CAM memory I / F") 14, CAM 15 for registering the source address of the received frame, and line transceiver 1
1, a MAC (medium access control) frame transmission / reception unit 16, a CAM status holding unit 17 that holds the status of the CAM 15, and an abort generation unit 18 that generates an abort signal for discarding a received frame. , An MPU interface unit (hereinafter, referred to as “MPU”) connected to an MPU 22 described later via the bus signal line 20.
I / F ”. ) 19, these detection unit 12, I / F
14, 19, a holding unit 17, and a control unit 21 connected to the generation unit 18, an MPU 22 that performs relay processing and address filtering in the CAM full state, and a RAM 23 that can register a source address.

The line transceiver 11 is connected to a LAN line and transmits / receives MAC data having a frame structure. The reception frame address detection unit 12 is a shift register that detects the source address data and the destination address data from the reception frame (MAC frame) received by the line transceiver 11.

The address data buffer 13 temporarily stores the address data detected by the received frame address detection unit 12. The CAM memory I / F 14 performs basic memory operations of the CAM 15, such as data search, data registration, and data deletion, based on commands from the control unit 21. The CAM 15 is a memory having the number of registration entries for one line (for example, the number of registration entries of 256), and the source address of the received frame is registered by an instruction from the control unit 21. For data, an active match signal is output to the CAM status holding unit 17 as an address search result. Further, when the storage capacity becomes full, the CAM 15 outputs a signal indicating the full state to the CAM status holding unit 17.

The MAC frame transmission / reception section 16 performs operations such as frame transmission / reception, buffering of the transmission / reception frame, and error detection. The CAM status holding unit 17 is a register that temporarily holds the data indicating the full state of the CAM and the address search result input via the CAM memory I / F 14.

The abort generation section 18 generates an abort signal to the MAC frame transmission / reception section 16 according to an instruction from the control section 21 in response to the abort determination. MPUI /
The F19 provides the MPU 22 with services such as presentation of the full state of the CAM 15 from the control unit 21 and reading / writing of the CAM entry.

The control unit 21 takes in the address data and the like detected by the received frame address detection unit 12, recognizes the frame reception, and based on this recognition, the CAM.
An access instruction to the CAM memory I / F 14. Further, the control unit 21 receives the CAM1 based on the data input from the CAM status holding unit 17.
The full state of 5 and the address search result are constantly monitored, and based on the search result, switching and abort of the search mode of the address filtering, that is, whether to discard the received frame is automatically determined. Further, when the number of registered entries in the CAM 15 becomes full, the control unit 21 notifies the MPUI / F unit 19 to that effect.

The MPU 22 is a device processor for controlling a program in the connection device, and is a MAC frame transmitting / receiving unit 1
From the reception notification from 6, the received frame is recognized, and a relay process for relaying the frame to another line is performed. Also,
When the CAM 15 is in the full state, the MPU 22 sends MP
By the notification from the UI / F unit 19, the switching of the search mode is recognized, and the destination address of the received frame is stored in the RAM 23.
If the matching address is registered in the above search, the relay process is not performed. If the matching address is not registered, the source address of the received frame is set to the RAM 2
3 is registered and relay processing of the frame is performed.

The RAM 23 is used to register the entry of the source address exceeding the storage capacity of the CAM 15, and is a memory which can be shared with other uses of the apparatus. Next, a processing operation of filtering the received frame of the connection device will be described. Note that normally, when the connection device is activated, the CAM has an empty entry, so the source address of the received frame is unregistered. The registration of the source address and the address filtering for receiving the frame from the line start at the same time as the operation of the device starts, and the registered addresses accumulate as the time elapses, but the addresses are not registered in duplicate, so the processing load, The frequency of registration processing for frame reception gradually decreases. Further, as the registered addresses are accumulated, the number of frames discarded by filtering increases.

In the address filtering method according to the present invention, the control unit 2 is operated during a heavy processing load period after the start of operation.
The MPU 22 takes over the filtering process when the storage capacity of the mounted CAM becomes full due to the number of registered addresses after performing the address filtering by 1. When the destination address is not registered, the abort signal for discarding the received frame is set to the above MA.
If the C-frame transmission / reception unit 16 does not output and the matching destination address is registered, the abort signal is output to the MAC frame transmission / reception unit 16.

First, when the current number of registered entries in the CAM 15 is not full below the capacity, the received frame address detection unit 12 causes the received frame source to detect the source of the received frame each time a frame is received from the circuit transceiver 11. Address data buffer 1
3 is temporarily stored in the CAM memory I / F 14
Output to.

The control unit 21 causes the CAM 15 to register the data of the source address via the CAM memory I / F 14, and the destination address of the received frame is C.
It is searched whether it is registered in AM15. This search is a CA input via the CAM status holding unit 17.
This is performed according to the state of the matching signal from M15. That is, the CAM 15 outputs the matching signal in the active state when the destination address of the received frame matches the registered destination address, and the passive state when the destination address of the received frame is not registered. The above matching signal of is output.

Here, when the destination address is not registered, the control unit 21 does not output the control signal instructing the discard of the received frame to the abort generation unit 18. As a result, the abort generation unit 18 does not output the abort signal to the MAC frame transmission / reception unit 16, and the MAC frame transmission / reception unit 16 outputs a notification indicating that there is a frame to be relayed and a reception frame to the MPU 22.

Therefore, the MPU 22 is
The received frame can be recognized and the frame relay process can be performed. If an address matching the destination address is registered in the CAM 15, the control unit 2
1 is a control signal for instructing the discard of this received frame,
Output to the abort generation unit 18. Accordingly, the abort generation unit 18 outputs the abort signal to the MAC frame transmission / reception unit 16, and the MAC frame transmission / reception unit 16
Discards the received frame.

Therefore, since the received frame is discarded, the MPU 22 does not move to the filtering process and the relay process. Next, when the current number of registered entries in the CAM exceeds the capacity and becomes full,
The CAM status holding unit 17 holds the data indicating the full state from the CAM 15. Control unit 2
1 takes in the above-mentioned data, and switches the search mode from the search mode of the destination address to the search mode of the destination address and the source address to perform the search process of the destination address and the source address of the received frame. Then, the control unit 21 fetches the search result from the CAM status holding unit 17, and determines whether or not to discard the received frame according to the search result. Also,
The control unit 21 notifies the MPUI / F unit 19 to that effect when the number of registered entries in the CAM 15 becomes full. The search result on the CAM is ANDed and held in the CAM status holding unit 17.

Here, when both addresses that match the destination address and the source address of the received frame are registered in the CAM 15, the control unit 21 sends a control signal instructing frame discarding to the abort generation unit 18. Output to. As a result, the abort generation unit 18 outputs an abort signal to the MAC frame transmission / reception unit 16, and the MA signal is transmitted.
The C frame transmitting / receiving unit 16 discards the received frame.

Therefore, since the received frame is discarded, the MPU 22 does not move to the filtering process and the relay process. If at least one of the source address and the destination address is not registered, the abort signal is sent from the abort generation unit 18 to the MAC.
Since it is not output to the frame transmitting / receiving unit 16, the M
The AC frame transmission / reception unit 16 outputs to the MPU 22 a notification indicating that there is a frame to be relayed and a received frame.

Therefore, the MPU 22 is
The received frame can be recognized and the frame filtering process and the relay process can be started. In this case, MP
If the source address is not registered in the RAM 23, the U 22 registers it, and also searches whether the destination address is registered in the RAM 23. Here, MPU22
When the destination address is registered in the RAM 23, the frame relay process is not performed, and when the destination address is not registered, the frame relay process is performed.

When the CAM is in the full state, the logical product of the search results of both the source address and the destination address is taken for the following reason. That is, for example, in the conventional search using only the destination address, the current CA
When the connection device receives a frame of a destination address registered on the CAM from an arbitrary source address that is not registered on M, the control unit outputs a command indicating frame discard, and the MPU The arbitrary source address cannot be recognized. As a result, the new source address cannot be registered in the RAM, and there is an inconvenience that a subsequent frame addressed to the source address will be omitted. Therefore, when the CAM becomes full, it is necessary to perform control to switch the search mode of address filtering in the above procedure.

Therefore, in this embodiment, when the processing load after the start of operation is large (when the CAM is not in the full state),
By performing the address filtering search using only the destination address as in the conventional method, the processing load of the MPU is reduced, and C
When the AM becomes full, the MPU takes over the filtering process and searches for address filtering by the source address and the destination address to prevent leakage of filtering. Therefore, the MPU can relay only necessary frames. This makes it possible to improve frame relay processing. Further, in the present embodiment, in the filtering process performed by the MPU, the registration of the transmission source address can be assigned to the memory (RAM) whose manufacturing cost is low, so that the manufacturing cost of the entire device can be reduced.

[0028]

As described above, according to the present invention, when a relay frame is received, the destination address of the relay frame is detected by the address detecting means, and the address is registered in the first storage means in which the address is mounted. If it is not registered, the transmission source address of the relay frame is registered in the first storage means, and the processing means performs the relay processing. In the address filtering method of the connecting device for discarding the relay frame by the control means, a monitoring step of monitoring by the control means whether the number of registered source addresses exceeds the storage capacity of the first storage means, When the number of the source addresses exceeds the storage capacity, the source address and the destination address of the received relay frame are detected by the address detecting means. A detection step of issuing, a first search step of searching by the control means whether the detected source address and destination address are registered in the first storage means, and both the source address and the destination address registered If it is set, the discarding step of discarding the relay frame by the control means, and if at least one of the source address and the destination address is unregistered, the processing means implements the source address. A second search step of registering the destination address in the second storage means and searching for the destination address registered in the second storage means;
If the destination address is registered in the search step of step 1, the processing means does not perform the relay processing of the relay frame. If the destination address is not registered, the processing means does not perform the relay processing of the relay frame. Since it includes a processing step of performing relay processing, it is possible to reduce the frequency of execution of filtering performed by the MPU without increasing the manufacturing cost.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a connection device using an address filtering method according to the present invention.

[Explanation of symbols]

11 line transceiver 12 received frame address detection unit 13 address data buffer 14 CAM memory interface unit (CAM memory I / F) 15 CAM 16 MAC frame transmission / reception unit 17 CAM status holding unit 18 abort generation unit 19 MPU interface unit (MPUI / F) 20 bus signal line 21 control unit 22 MPU 23 RAM

Claims (1)

[Claims] 1. When a relay frame is received, the destination address of the relay frame is detected by the address detection means, and the control means searches for whether the address is registered in the installed first storage means. In this case, the source address of the relay frame is registered in the first storage means, the processing means performs the relay processing, and if registered, the control means discards the relay frame. In the address filtering method of the device, a monitoring step of monitoring by the control means whether the number of registered source addresses exceeds the storage capacity of the first storage means, and the number of source addresses is stored in the storage When the capacity is exceeded, a detecting step of detecting the source address and the destination address of the received relay frame by the address detecting means, and the detecting step. A first search step of searching by the control means whether the source address and the destination address are registered in the first storage means, and the relay if both the source address and the destination address are registered. A discarding step of discarding the frame by the control means, and if at least one of the source address and the destination address is unregistered, the processing means registers the source address in the second storage means to be mounted. And a second search step for searching whether the destination address is registered in the second storage means, and when the destination address is registered in the second search step, the processing means When the relay processing of the relay frame is not performed and the destination address is not registered, the processing unit performs the relay processing of the relay frame by the processing device. Dress filtering method.