JPH03101437A - Address learning system - Google Patents

Abstract

PURPOSE:To improve the efficiency of learning and to reduce the probability of occurrence of multiple address in a trunk line LAN by enabling the learning of a filtering database(FDB) even when a bridge does not receive a frame from a trunk line LAN or a branching line LAN, that is, independently of whether or not the bridge itself is a destination. CONSTITUTION:A FDB 14 learns the terminal address information of a branch LAN connected to its own bridge from a branch LAN reception path 8, outgoing terminal address information of a branch line LAN connected to other bridge being a destination from a trunk line LAN reception path 5, and reception terminal address information of the branch line LAN connected to the other bridge independently of whether its own bridge is a destination from a study path 11. Thus, the probability of the destination terminal address information by the FDB 14 is high and the probability of the generation of multiple address on the trunk line LAN1 is decreased.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a learning method for a filtering database (FDB) of a bridge connecting a ring sub-trunk #LAN and a branch LAN. The present invention relates to a method in which a learning-only path (hereinafter referred to as learning path) is provided as a path, and the FDB is made to learn terminal address information from the learning path.

[Conventional technology]

In a system that connects a main line LAN and a branch line LAN with a bridge, does the bridge send data from a terminal connected to the branch line LAN to its own bridge's branch line LAN?
In some cases, a database is provided for determining whether the branch line LAN of another bridge is connected or not. The database has entries that store terminal address information seen from the bridge. The entry has fields such as terminal address and bridge number. When the bridge receives data (frame) from the branch LAN, it inputs the source terminal address from the SA (source) field of the frame into the terminal address field of the entry.

Register the own bridge number in the bridge number field of the entry. When the bridge receives a frame from the main LAN, it sets the source bridge number from the SA field of the frame to the bridge number field of the entry, and sets the source terminal address written in the INFO field of the frame to the terminal address of the entry. Register in the field. Each entry has a timer attached to it (aging timer), which is reset when the entry is registered. Entries are deleted when the aging timer times out.

The above is the basic learning method of the database, and the database is called a filtering database (FDB) because the bridge searches the database for frames received and relays/discards them. Incidentally, related learning methods of this type include, for example, Japanese Patent Application Laid-Open No. 63-9323.
No. 5 is mentioned.

Now, in the above learning method, the bridge's FDB is learned only when the bridge receives a frame from the trunk 11 LAN or branch LAN, and the learned address information also includes terminal information under the own bridge and the own bridge as the destination. I was only able to learn terminal information from a certain source.

[Problem to be solved by the invention]

In the above conventional technology, the bridge is connected to the main LAN or branch LA.
When a frame is not received from N, no consideration is given to learning, and the terminal address information that is learned can only be learned from the terminals under the own bridge and the terminal address information of the source whose destination is the own bridge. was there.

In the method in which the bridge that connects the main LAN and the branch LAN refers to the FDB mentioned above to determine whether or not a frame can be relayed, the destination terminal address in the communication frame received from the branch LAN does not exist in the FDB entry. In this case, all bridges receive (broadcast) the relevant frame on the main LAN.
Send as. This frame must be received by all bridges and make a relay decision based on FDB reference, which increases the bridge overhead and reduces the throughput of the entire system.

Additionally, in the case of a multi-ring configuration in which the trunk LAN is physically or logically composed of multiple transmission lines, one method of broadcasting within the trunk LAN is to send the same frame to all rings. When such a method is used, the occurrence of one broadcast occupies the bandwidth of one main LAN by the number of rings. From the above,
It is desirable to keep the probability of broadcast occurrence as low as possible.

To achieve this, instead of learning only the frames received by the user for entry into the FDB, as in the prior art, it is necessary to extract the address information of the frame even if the destination is not the user, and send the address information to the FDB. should be the subject of entry learning.

The purpose of the present invention is to connect the bridge to the main fiLAN or branch line L
To enable learning to FDB even when no frame is received from an AN. That is, the purpose is to enable learning to the FDB regardless of whether the destination is the destination, and to suppress the occurrence of broadcast within the trunk LAN. This makes it possible to effectively utilize system resources and provide users with low response and high throughput.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a bridge that connects a branch LAN and a main LAN with a communication path from the main mLAN, where the destination bridge number is the own bridge number or the destination bridge number is the same. In addition to a receiving path for receiving mainline LAN frames with bridge numbers indicating information, a learning path is provided for learning terminal address information in mainline LAN frames whose destination bridge number is a bridge number other than one's own. The source bridge number is sent from the SA field of the trunk LAN frame to the bridge number field of the FDB entry through two types of paths: the path and the learning path described above, and the INFO of the trunk LAN frame is sent to the bridge number field of the FDB entry.
By registering the source terminal address in the terminal address field of the FDB entry, the FDB
learn address information.

In addition, if the trunk LAN has a multi-ring configuration, a learning path is provided for all rings, and in addition to the method of learning from the learning paths of all rings, the paths from all rings are aggregated into one learning path. It is also possible to perform learning from one learning path.

In a trunk LAN, if a mini-packet method is used in which a branch LAN frame is divided into fixed-length cells, sent as trunk LAN cells to the trunk LAN, and assembled into a branch LAN frame at the destination bridge, the bridge
Efficiency is improved by having the FDB learn terminal address information only from the first cell and single cell among the four types of cells: the first cell, intermediate cell, last cell, and single cell on the receiving path and learning path of the AN. It is also conceivable to have the students engage in some kind of learning.

[Effect]

By providing a learning path, even when the bridge is not receiving frames addressed to itself from the main LAN, source terminal address information is learned to the FDB by frames addressed to itself or other bridges from the learning path. .

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 10.

As a first embodiment of the present invention, a case where the trunk LAN is a single-channel LAN will be described.

FIG. 1 is a block configuration diagram of a bridge provided with a learning path according to an embodiment of the present invention, and FIG. 2 is a system configuration diagram of a network to which the bridge shown in FIG. 1 is applied. In Figure 2, 1 is a relatively high-speed trunk LAN, 2-1 or 2
-4 is the bridge, 3-1.3-2 is the bridge 2-1.2
-2 is a branch line LAN connected to the main line LAN1. Branch line LAN3-1.3'-2 has terminal 4-1.4-
2 are connected. Although not shown in FIG. 2, a branch line LAN similar to the branch line LAN3-1.3-2 is connected to the main line LAN1 by a bridge 2-3.2-4.

As shown in FIG. 1, in the bridge 2-1.2-2, the trunk LAN reception path 5 and trunk LAN transmission path 6
Connected to AN interface 7, bridge and trunk LA
It is possible to send and receive trunk LAN frames to and from N. Further, the branch LAN transmission path 8 and the branch LAN reception bus 9 are connected to the branch LAN interface 1o,
Branch line LAN frames can be transmitted and received between the bridge and the branch MLAN. Furthermore, the learning path 1 provided in the present invention is connected to the trunk LAN interface 7, and it is possible to receive trunk LAN frames from this path as well. In addition, the learning path, trunk LAN frame and branch line L
Details of the AN frame will be described later.

12 is a buffer memory for holding data from the trunk LAN interface 7 or the branch LAN interface 10;
Interface 7 or branch LAN interface 10
Relay/discard data.

As shown in FIG. 9, the control unit 13 is composed of a microprocessor 70 and a memory 71 that stores programs and data. The control unit 13 connects the FDB 14 to the trunk LAN interface 7 in order to issue the above-mentioned relay/discard instructions.
And from the branch LAN interface 10, it learns the terminal address information of the branch LAN under its own bridge or another bridge. The service address information is collected from frames from the trunk LAN reception path 5, the branch LAN reception path 9, and the learning path 11. Note that the bridges 2-3 and 2-4 also have the same configuration as in FIG. 1.

FIG. 3 shows an example of a frame format applied in the network of FIG. 2. However, only fields related to the present invention are shown, and fields such as frame check sequence are omitted.

In FIG. 2, bridges 2-1 to 2-4 are each given a unique bridge number, and terminals 4-1 and 4-2 are each given a unique terminal address.

A frame consists of a destination address field DA, a source address field SA and an information field INFO. Each field contains the above bridge number,
Terminal address and support 41i! Data from the LAN is set.

In the branch line LAN frame 20 flowing on the branch line LAN, a destination terminal address is set in the destination address field DA, a source terminal address is set in the source address field SA, and data from the branch line LAN is set in the information field INFO. In the trunk LAN frame 21 flowing on the trunk LAN, a destination bridge number is set in the destination address field DA, a source bridge number is set in the source address field SA, and a frame from the branch LAN is set in the information field INFO. Note that when the destination is to be broadcast (addressed to all bridges), a special pattern for broadcast is set in the destination address field DA.

FIG. 4 shows the entry structure of the FDB 14. As shown in FIG. 4, each entry 22 has fields for setting the terminal address and the bridge number of the bridge to which the branch LAN having the terminal is connected.

Next, the operation of one embodiment of the present invention will be explained using the flowcharts shown in FIGS. 5 to 7. Furthermore, Fig. 5 shows the learning procedure of the bridge, Fig. 6 shows the processing procedure of the bridge when receiving a frame from the branch LAN, and Fig. 7 shows the processing procedure of the bridge when receiving a frame from the main LAN. . The operations shown in FIGS. 5 to 7 are performed by the microprocessor 70. of the control unit 13. It is executed by the memory 71.

First, using the flowchart in FIG. 5, the learning procedure for the bridge is as follows: learning procedure from the branch LAN, trunk A! L.A.
The learning procedure from N and the learning procedure from learning path will be explained.

A procedure for learning terminal address information from a branch LAN will be explained. In the bridge 2-1, when the branch line LAN frame 20 is received from the branch line LAN 3-1 to the branch line LAN interface 10 through the branch line LAN reception path 9, the control unit 13 selects the source terminal from the source address field SA of the branch line LAN frame 20. Step 31): Read the address.

It is checked whether the source terminal address is registered in the FDB 14 (step 32). If it is not registered, the control unit 13 checks whether there is a free entry in the FDB 14 (step 33). If there is a free entry, the control unit 13 registers the source terminal address and own bridge number in that entry (step 35), since the address information is from the branch LAN (step 34).
).

Furthermore, if the source terminal address is registered in the FDB 14, the control unit 13 does not perform learning (step 32).

If there is no free entry in the FDB 14, the control unit 13 does not perform learning (step 33).

The procedure for learning terminal address information from the trunk mLAN will be explained. In the bridge 2-1, when the trunk LAN frame 21 is received from the trunk LANI to the trunk LAN interface 7 through the trunk LAN reception path 5, the controller 1
3 is the information field INF of the trunk LAN frame 21.
Step 37) Read the source terminal address from O.
, it is checked whether the source terminal address is registered in the FDB 14 (step 32). If it is not registered, the control unit 13 checks whether there is a free entry in the FDB 14 (step 33). If there is a free entry, the control unit 13 checks the address information from the trunk LAN ( Step 34) The above source terminal address and the source address field S of the trunk LAN frame 21
Register the source bridge number from A in that entry (
Step 36). Other processing is similar to the address information learning procedure from the branch LAN described above.

The procedure for learning terminal address information from a learning path will be explained. In the bridge 2-1, from the trunk LAN 1 to the trunk LAN interface 7 through the learning path 11,
Upon receiving the IX L A N frame 21, the control unit 1
3 performs a procedure similar to the terminal address information learning procedure from the trunk LAN.

The above is the bridge learning procedure.

Next, the processing procedure of the bridge when receiving a frame from the branch LAN will be explained using the flowchart of FIG.

At bridge 2-1, from branch line LAN3-1 to branch line L
Through the AN reception path 9, the branch LAN interface 1
0 receives the branch line LAN frame 20 (step 4
1), the control unit 13 reads the destination terminal address from the destination address field DA of the branch LAN frame 20,
Check whether the destination terminal address is registered in the FDB 14 (step 42), and if it is registered,
The control unit 13 checks whether the destination bridge number matches the own bridge number (step 43). If the destination bridge number matches the own bridge number, the control unit 13 discards the frame.

Further, if the destination bridge number does not match the own bridge number, the control unit 13 sets F in the destination address field DA.
Bridge number 1 registered in DB14, own bridge number in source address field SA, information field I
Main line L with its branch line LAN frame 20 set to NFO
Transmit the AN frame 21 to the main LAN (step 4
5) If the destination terminal address is not registered in the FDB 14, the control unit 13 broadcasts it in the destination address field DA, the own bridge number in the source address field SA, and the branch line LAN frame 2 in the information field INFO.
The trunk LAN frame 21 in which 0 is set is transmitted to the trunk LAN (step 46).

The above is the processing procedure of the bridge when receiving a frame from the branch LAN.

Next, the processing procedure of the bridge when receiving a frame from the trunk LAN will be explained using the flowchart of FIG.

In bridge 2-1, from trunk LAN1 to trunk LAN
When the trunk LAN frame 21 is received at the trunk LAN interface 7 through the reception path 5 (step 51),
The control unit 13 reads the destination terminal address from the information field INFO of the trunk LAN frame 21 and checks whether the destination terminal address is registered in the FDB 14 (step 52). If it is registered, the control unit 13
checks whether the destination bridge number matches the own bridge number (step 53). If the destination bridge number matches the own bridge number, the control unit 13
The information field part of the AN frame 21 is connected to the branch LAN.
It is transmitted to the branch LAN as frame 2o (step 54). Furthermore, if the destination bridge number does not match the own bridge number, the control unit 13 discards the frame (step 55). If the destination terminal address is not registered in the FDB 14, the control unit 13 converts the information field part of the trunk LAN frame 21 into the branch LAN frame 2.
o to the branch LAN (step 54).

The above is the processing procedure of the bridge when receiving a frame from the trunk LAN.

As explained above, in FIG. 1, the terminal address information of the branch LAN connected to the own bridge is transmitted from the branch LAN reception path 8, and the terminal address information of the branch LAN connected to the own bridge is transmitted from the main LAN reception path 5 to other bridges whose destination is the own bridge. The source terminal address information of a branch line LAN connected to another bridge is transmitted from the learning path 11 to the receiving source terminal address information of a branch line LAN connected to another bridge, regardless of whether the own bridge is the destination.
Therefore, in the bridge processing procedure when receiving a frame from the branch LALAN in Figure 6, the branch LALAN
When receiving N and trunk LAN frames, there is a high probability that the destination terminal address information has been learned in the FDB.
The probability of broadcast occurrence on the trunk LAN is lowered.

A modification of the first embodiment of the present invention includes three processing procedures shown in FIGS. 5 to 7: a learning procedure in the bridge, a processing procedure when receiving a branch LAN frame, and a processing procedure when receiving a trunk LAN frame. By performing parallel processing, prioritizing and controlling each process, or performing only learning processing for a certain period after system startup, learning efficiency is increased, the probability of broadcast occurrence is lowered, and the main It becomes possible to use the LAN effectively.

As a second embodiment of the present invention, a case where the trunk LAN is a multi-ring type will be described. In Figure 1, the trunk LAN
If I is a multi-ring type, by setting a learning path from each ring of the trunk LAN corresponding to the ring and having the FDB 14 learn the terminal address information from each learning path, it will be the same as when the trunk LAN is a single ring type. The learning method can be easily inferred.

As a modification of the second embodiment of the present invention, by connecting a queue control circuit 62 shown in FIG. 8 to each ring, the learning path can be easily transitioned from a single ring type to a multi-ring type. In FIG. 8, 60 indicates a multi-ring of the trunk LAN, and 61 indicates a learning path from each ring. The queue control circuit 62 has a queue buffer memory 63 at each input.
This circuit provides a selection circuit 64 for outputting to one learning path 11. The selection circuit 64 is a circuit that selects one input from the inputs of the plurality of queue buffer memories 63 and outputs it. This method selects the buffer memory 63.

As Embodiment 3 of the present invention, a case will be described in which the trunk LAN in Embodiments 1 and 2 is of the mini-packet type.

Figure 10 shows the branch mLA applied in the network of Figure 2.
An example of an N frame 20 and a trunk LAN cell is shown. However, only fields related to the present invention are shown, and fields such as check sequence are omitted. The branch LAN frame 20 has already been described in the first embodiment. Main line LA
N cells have a destination address field DA, a source address field SA, and a fixed length information field IN.
Consists of FO. The head of the information field INFO includes a field PSN indicating the type of cell, which will be described later.

The bridge number, terminal address, cell type, and data from the branch LAN are set in each field. Due to the relationship between the length of the branch line LAN frame 20 and the length of the information field INFO of the main line LAN cell, the main line L
AN cells are classified into four types of cells. Figure 10(a)
When the cell is divided into three or more cells, the first cell to be divided is designated as the first cell 80. The last cell to be divided is the last cell 82. The cell divided between them is referred to as an intermediate (Next) cell 81. 2
When divided into two cells, F cell 80 and L cell 82
It is.

When the branch LAN frame 20 enters the information field INFO of a trunk LAN cell, the trunk LAN cell is assumed to be a single cell 83 as shown in FIG. 10(b). The terminal address information, which is a pair of the terminal address and the bridge number of the bridge under which the terminal belongs, is included in the F cell 80 and S cell 83 of the four types of trunk LAN cells, so the F cell 80 and the S cell It can be seen that only 83 needs to be targeted for learning to FDB.

From the above, in FIG. 1, the first field PSN of the information field INFO of the trunk LAN cells from the trunk BLAN reception path 5 and learning path 11 is examined, and the transmission of trunk LAN cells indicating the F cell 80 and S cell 83 is determined. FDH receives the source bridge number from the source address field SA and the source terminal address from the information field INFO.
Let them learn. The operation of this embodiment can be easily inferred from the above description.

From the above explanation, it can be easily inferred that the same learning method as in the first and second embodiments can be applied even when the trunk LAN is a mini-packet method.

〔Effect of the invention〕

According to the present invention, the learning efficiency of FDB is improved and the trunk LAN
It is possible to reduce the probability of occurrence of broadcasting, making it possible to effectively utilize system resources and provide users with low response and high throughput.

Further, according to the present invention, the above effects can be obtained even when the main line LAN is of the multi-ring type and when the main line LEAN is of the mini-packet type. By providing a queue control circuit that converts the learning paths from each ring into one learning path, the learning path can be easily transitioned from a single ring type to a multi-ring type, and the above effects can also be obtained.

[Brief explanation of drawings]

Figure 1 is a block configuration diagram of a bridge provided with a learning path according to an embodiment of the present invention, Figure 2 is a system configuration diagram of a network to which the bridge shown in Figure 1 is applied, and Figure 3 is the system shown in Figure 2. FIG. 4 is a diagram showing the entry structure of the FDB provided in the bridge of FIG. 1, and FIGS. 5 to 7 explain the operation of an embodiment of the present invention. Figure 8 is a block diagram of the multi-ring trunk LAN and bridge queue control circuit, Figure 9 is a block diagram of the bridge control section, and Figure 10 is a frame applied to the system in Figure 2. FIG. 3 is a diagram showing the format of a cell. 1... Main LAN, 2-1 to 2-4... Bridge, 3-1.3-2... Branch mLAN, 4-1.4-2
...Terminal, 5.. Main line LAN reception path, 6.. Main line LAN transmission bus, 7.. Main line LAN interface, 8.. Branch mLAN transmission path, 9.. Branch LAN reception bus, 10.・・・Branch line LAN interface, 11・
...Learning path, 12...Buffer memory, 13...
Control unit, 14...filtering database (FD
B), 20... Branch LAN frame, 21... Trunk LAN frame, 22... FDB entry, 31 to 38... Bridge learning process, 41 to 46...
- Bridge processing when receiving branch line LAN frames, 51 to 56... Bridge processing when receiving main line LAN frames. 6%'Multi-ring LAN, 61...Learning path, 6
2... Queue control circuit, 63... Queue buffer memory 564... Selection circuit, 7o... Microprocessor, 71... Memory, 8o... Leading cell, 81...
... intermediate cell, 82 river final cell, 83... single cell. 17th Figure 2 Figure 3 Closed Figure 5

Claims (1)

[Claims] 1. A plurality of relatively low-speed branch LANs connecting terminals;
It consists of a relatively high-speed main line LAN for connecting the above-mentioned branch line LANs, and a bridge for connecting the above-mentioned main line LAN and the above-mentioned branch line LAN, and the terminal is connected to the plurality of branch line LAs.
N, the bridge has a valid and unique bridge number within the trunk LAN, and the bridge has terminal address information that pairs the terminal address of the terminal with the bridge number. Database that stores (filtering database)
The terminal address information is created in the database by learning the terminal address information in the communication frames from the branch LAN and the trunk LAN, and the bridge learns the terminal address information in the communication frames from the branch LAN and the trunk LAN. receive all communication frames (branch line LAN frames),
By referring to the above database, the above branch line LA
When deciding whether to relay/discard the N frame and relaying the branch LAN frame to the main LAN, the bridge number obtained by the above reference is used to connect the branch LAN frame to the main LAN.
A hierarchical LA that encapsulates frames, specifies the destination of the trunk LAN frame, and sends it to the destination bridge.
In the N interconnection system, when the trunk LAN is a single ring type LAN consisting of one transmission path both physically and logically, in the bridge,
Not only the receiving path that receives the trunk LAN frame when the bridge number indicating the destination of the trunk LAN frame is the own bridge number or the bridge number indicating broadcasting, but also the bridge number other than the bridge number By providing a learning-only path for learning the terminal address information from the trunk LAN frame, which is a number, it is possible to learn the terminal address information from the learning-only path to the database in addition to the receiving path. An address learning method characterized by: 2. In the hierarchical LAN interconnection system according to claim 1, the trunk LAN is a multi-ring type LAN that is physically or logically composed of a plurality of transmission lines.
When the bridge is an AN, the main line LA
When the bridge number indicating the destination of the N frame is the own bridge number or the above bridge number is the bridge number indicating broadcasting, not only the reception path that receives the above trunk LAN frame but also the bridge number other than the above bridge number A dedicated learning path is provided for each ring of the multi-ring LAN to learn the terminal address information from the trunk LAN frame which is the number, and one or more paths are provided to the database in addition to the receiving path. An address learning method characterized in that it is possible to learn the terminal address information also from the learning-only path. 3. In the learning-only path described in claim 2, a selection circuit is provided for consolidating the one or more learning-only paths corresponding to each ring into a single learning-only path. According to the address learning method, even in a multi-ring type LAN, it is possible to learn the terminal address information from the only learning-only path to the database in addition to the receiving path. . 4. When relaying the branch line LAN frame to the main line LAN, instead of the encapsulation method in which the branch line LAN frame is encapsulated into a main line LAN frame, the branch line LAN frame is divided into fixed length cells, and one or more cells are divided into one or more cells. As a cell of
A mini packet that specifies the destination of the cell using the bridge number obtained by referring to the database, sends it to the destination bridge, and assembles the received cell into the branch LAN frame at the destination bridge. In a hierarchical LAN interconnection system using this method on the trunk LAN, the cells are divided into the first (\F\rst) cell, middle (\N) cell by dividing the branch LAN frame.
In the address learning method described in claim 1, the address learning method is classified into four types: \ext) cell, final (\L\ast) cell, and single (\S\ingle) cell. When learning the terminal address information from the receiving path and the learning-only path of the trunk LAN, the above information is learned only from two types of cells, the first cell and the single cell, among the four types of cells. An address learning method according to any one of claims 1, 2, and 3, characterized in that terminal address information is learned.