JPH07336373A - Traffic control bridge - Google Patents

Abstract

PURPOSE:To prevent the fault of a transmission line by repeating the frame of a simultaneous multi-address to the network on other side or limiting the repeating operation of the frame by depending on whether the value counted for fixed time is smaller or larger than a prescribed value. CONSTITUTION:A bridge 1 is composed of a CSMA/CD, a bridge repeating processing part 11, transmission parts 12a and 12b, reception parts 13a and 13b, and simultaneous multi-address count pants 14a and 14b. The frames received by the reception parts 13a and 13b from transmission lines 2a and 2b are processed by a processing part 11, and the number of simultaneous multi- address is counted by the count parts 14a and 14b for fixed time. By depending on whether these count values are prescribed values or below/more, the processing part 11 transmits the simultaneous multi-address frame without a limitation or with the limitation from the transmission parts 12a and 12b to the transmission lines 2a or 2b. Thus, the fault of the transmission line due to the rise of traffic and the generation of broadcast storm can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traffic control bridge, and more particularly to a bridge for relaying a frame from one network to another network.

[0002]

2. Description of the Related Art Generally, when two networks are connected by a bridge, a frame transmitted from a node in one network is relayed by the bridge and transmitted to a node in the other network. The frame includes a frame for a specific node and a broadcast frame.

Conventionally, a broadcast frame has been unconditionally relayed in this type of bridge.

[0004]

In the above-mentioned conventional bridge, since the broadcast frame is relayed unconditionally, if the number of broadcast frames is large, the traffic increases or a broadcast storm occurs. There was a drawback.

Japanese Patent Laid-Open No. 63-194444 discloses a local area network device in which a plurality of nodes are connected by a plurality of networks having different characteristics.
This only selects the network used for packet transfer and cannot solve the above drawbacks.

The present invention has been made to solve the above-mentioned drawbacks of the prior art, and its purpose is to prevent traffic from increasing even when a large number of broadcast frames occur.
Another object of the present invention is to provide a traffic control bridge for realizing a communication system in which a broadcast storm does not occur. Is to provide.

[0007]

A traffic control bridge according to the present invention is connected to first and second networks and performs a relay operation for relaying a broadcast frame from the first network to the second network. A bridge for performing the relay, which includes relay control means for interrupting the relay operation when the number of the broadcast frames per fixed time exceeds a predetermined value.

[0008]

The relay operation between networks is limited when the number of broadcast frames per fixed time exceeds a predetermined value.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a first embodiment of a traffic control bridge according to the present invention.

In the figure, in a first embodiment of the present invention, a network connected to a traffic control bridge is a CSMA / CD (Carrier Sens).
eMultiple Access with Col
It is assumed that the network is a region detection network. That is, referring to FIG. 1A, networks 2a and 2b are connected to the bridge 1, and a station 3 is connected to the network 2a.
A station 3b is connected to each of a and the network 2b. Then, the bridge 1 performs the frame relay operation, so that the station 3a and the station 3
Frames are transmitted and received to and from b.

In the state shown in FIG. 1A, the relay operation of frames in the bridge 1 is not limited at all, and since the number of broadcast frames per fixed time is small, the broadcast frames are also relayed. is there. In this state, the bridge 1 operates similarly to a conventional bridge.

On the other hand, the state of FIG. 1B is a state in which the frame relay operation in the bridge 1 is restricted,
Since the number of broadcast frames per fixed time is large, the relay of broadcast frames is limited.

Next, an example of the internal configuration of the bridge 1 will be described with reference to FIG. 2, the same parts as those in FIG. 1 are designated by the same reference numerals.

In the figure, a bridge 1 is connected to networks (hereinafter referred to as transmission lines) 2a and 2b. The bridge 1 includes a CSMA / CD receiver 13a that receives a frame from the transmission path 2a, and a broadcast count unit 14a that counts the number of broadcast frames among the received frames. Has been done.

The bridge 1 of this example also includes a CSMA / CD receiver 13ba for receiving a frame from the transmission line 2b.
And a broadcast count unit 14b that counts the number of broadcast frames among the received frames.

Furthermore, the bridge 1 of this example uses CSMA / frames for frames received by the receivers 13a and 13b.
The CSMA / CD bridge relay processing unit 11 which outputs to the CD transmission units 12a and 12b, respectively, and which outputs the broadcast frame when the count values of the counting units 14a and 14b at a certain time are larger than a predetermined value, and the relay. It is configured to include CSMA / CD transmitters 12a and 12b for transmitting outputs from the processor 11 to the transmission lines 2a and 2b, respectively.

In such a structure, the frame received from the transmission line 2a is received by the receiving unit 13a, and the relay processing unit 1
At the same time as being passed to 1, it is passed to the counting section 14a and monitored. If the number of broadcast frames does not exceed a certain value, the broadcast mode is relayed without restriction. As a result, all the received frames are sent to the transmitter 12b and sent to the transmission line 2b. Transmission line 2
The frame received from b is similarly sent to the transmission line 2a.

Here, when a broadcast storm occurs and a broadcast frame is abnormally generated on one transmission path, or when a large number of broadcast frames are generated even in a normal state, Since the number of broadcast frames exceeds a certain value, the broadcast frame is restricted. Then, of the received frames, other than the broadcast frame, it is normally sent to the transmission unit 12a and sent to the transmission line 2b, but the relay of the broadcast frame is cut off and not sent to the transmission line 2b. That is, all broadcast frames are discarded. As a result, it is possible to prevent the increase in traffic and the failure of the transmission path due to the broadcast storm.

The above control flow is represented by broken lines H20 and H21.
Indicated by.

In the above-described first embodiment, the relay operation is stopped when the number of broadcast frames per fixed time exceeds a predetermined value, that is, the broadcast frame is not relayed at all. However, an embodiment in which it is not relayed at all but limited to some extent is also conceivable. For example, instead of discarding all the broadcast frames, only some of them may be discarded, and the ones not discarded may be relayed. This also partially restricts the relay of broadcast frames, and can prevent the increase in traffic and the failure of the transmission path due to the broadcast storm.

FIG. 3 shows an example of the address system of the CSMA / CD transmission line. In the CSMA / CD transmission path, MAC (Media Access Control)
l) Address is I / G (Individual / Gr)
The (up) bit distinguishes an individual address from a broadcast address including a broadcast address. In this case, when the MSB I / G bit is "0", it is an individual address, and when it is "1", it is a broadcast address. Then, when the other bits are all "1" and all of the addresses from MSB to LSB are "1", it is defined as a broadcast address. In addition,
If the other bits are not all "1", the group broadcast address is used.

From the above, in the bridge relay processing unit 11, M
By first determining whether the I / G bit of the AC address is "1", it can be determined whether the frame is a broadcast frame. If the MAC address is all "1", it can be determined that the broadcast frame is a broadcast frame.

Referring again to FIG. 1, the operation of the bridge of this embodiment will be further described.

In the state shown in FIG. 3A, the number of simultaneous broadcast frames is small. Therefore, since the number of broadcast frames counted per fixed time is small,
The broadcast frame transmitted from the station 3a as indicated by the arrow Y2 passes through the bridge 1 without any limitation,
It is sent to the transmission line 2b as indicated by an arrow Y3. As a result, the station 3b receives the broadcast frame. Similarly, the broadcast frame transmitted from the station 3b also passes through the bridge 1 and is transmitted to the transmission line 2a.

On the other hand, the state shown in FIG. 6B is a state in which the number of broadcast frames on the transmission line 2a is large.
When the count number of the broadcast frame per fixed time becomes larger than a certain value, the broadcast frame sent from the station 3a as indicated by the arrow Y2 is sent to the transmission path 2a, but is broadcast to the transmission path 2b. The transmission of broadcast frames is restricted in bridge 1.

In this state, if a simultaneous broadcast frame is relayed, the broadcast storm generated on one transmission path is relayed, and the broadcast storm spreads over the entire transmission path. When a broadcast storm occurs, the number of broadcast frames increases abnormally, interrupts normal communication, and stalls at some stations.

Therefore, the bridge 1 prevents the broadcast storm and the excessive traffic increase by limiting the passage of the broadcast frame according to the frequency of occurrence of the broadcast frame.

FIG. 4 is a block diagram showing the configuration of a second embodiment of the traffic control bridge according to the present invention, and the same portions as those in FIGS. 1 and 2 are designated by the same reference numerals.

In the figure, the second embodiment of the present invention is premised on the case where the transmission line connected to the traffic control bridge is a token ring network. That is, referring to FIG. 1A, the bridge 1 is connected to the transmission lines 20a and 20b, the transmission line 20a is connected to the station 3a, and the transmission line 2b is connected to the station 3b. And bridge 1
Performs a frame relay operation, whereby frames are transmitted and received between the stations 3a and 3b.

The state of FIG. 3A is a state in which the frame relay operation in the bridge 1 is not limited at all, and the simultaneous broadcast LLC (Logical) per fixed time is performed.
Since the number of Link Control frames is small, a broadcast frame is also relayed. In this state, the bridge 1 operates similarly to a conventional bridge.

On the other hand, the state of FIG. 2B is a state in which the frame relay operation in the bridge 1 is restricted,
Since the number of broadcast LLC frames per fixed time is large, relay of broadcast LLC frames is limited.

Next, an example of the internal structure of the bridge 1 will be described with reference to FIG. 5, the same parts as those in FIG. 4 are denoted by the same reference numerals.

In the figure, the bridge 1 has a transmission line 20a.
And 20b are connected. The bridge 1 includes a token ring receiving unit 113a that receives a frame from the transmission path 20a, and a broadcast counting unit 114a that counts the number of broadcast LLC frames among the received frames. Has been done.

Further, the bridge 1 of this example has a token ring receiving section 113b for receiving a frame from the transmission line 2b.
and a broadcast broadcast counting unit 114b that counts the number of broadcast broadcast LLC frames among the received frames.

Furthermore, the bridge 1 of the present example outputs the frames received by the receiving units 113a and 113b to the token ring transmitting units 112a and 112b, respectively, and the count values of the counting units 114a and 114b at a predetermined time. A token ring bridge relay processing unit 111 that cuts off the output of the broadcast LLC frame when it is larger, and an output from this relay processing unit 111 is transmitted through the transmission path 2
Token ring transmitter 112 for transmitting to a and b respectively
a and 112b are included.

The judgment of the count value is made by the firmware.

In such a configuration, the frame received from the transmission line 2a is received by the receiving unit 113a, passed to the relay processing unit 111, and at the same time passed to the counting unit 114a for monitoring. If the number of broadcast LLC frames does not exceed a certain value, the broadcast LLC frames are relayed without restriction. As a result, all the received frames are sent to the transmitter 112b and sent to the transmission line 2b. The frame received from the transmission line 2b is also sent to the transmission line 2a.

Here, when a broadcast storm occurs and a broadcast LLC frame is abnormally generated on one of the transmission lines, or even in a normal state, the broadcast LL is broadcast.
When a large number of C frames are generated, broadcast LL
Since the number of C frames exceeds a certain value, bridge 1
Reduce the token retention time parameter in.
Then, forwarding of the frame sent to the transmission unit 112b and sent to the transmission path 2b is limited.

That is, if the token can be held for a short period of time, the bridge 1 must immediately release the token, so that the data cannot be transmitted for a long time. This limits the forwarding of the frame sent to the transmission line 2b. As a result, it is possible to prevent the increase in traffic and the failure of the transmission path due to the broadcast storm. The above control flow is shown by broken lines H50 and H51.

The counting units 114a and 114b are again used.
When the count value per constant time of is smaller than the predetermined value, if the parameter of the token holding time in the bridge 1 is increased, the frame transmission from the bridge 1 to the other transmission path can be preferentially performed. it can. That is, if the token can be held for a long time, the bridge 1
The data can be sent for a long time, and the frames sent to the other transmission path are actively forwarded.

FIG. 6 shows an example of the address system of the token ring transmission line. In the token ring transmission path, the MAC address distinguishes an individual address and a broadcast address including a broadcast by an I / G bit. in this case,
When the I / G bit which is the MSB is "0", it is an individual address, and when it is "1", it is a broadcast address. The other bits are all “1” and the MSB to LS of the address
The case where all of up to B is "1" is defined as a broadcast address. If the other bits are not all "1", the group broadcast address is used.

From the above, in the bridge relay processing unit 111,
By first determining whether the I / G bit of the MAC address is "1", it is possible to determine whether the frame is a broadcast frame. Then, if the MAC address is all "1", it can be determined that it is a simultaneous broadcast LLC frame.

In the token ring, when the frame control field of the broadcast frame is LLC, it becomes a broadcast LLC frame and is generally relayed outside the own ring. On the other hand, when the frame control field is a MAC frame, even a broadcast frame is not relayed by the bridge.

The operation of the bridge of this embodiment will be further described with reference to FIG. 4 again.

The state of FIG. 7A is a state in which the number of simultaneous broadcast LLC frames is small. Therefore, since the count number of the broadcast LLC frame per fixed time is small, the broadcast LLC frame transmitted from the station 3a as shown by the arrow Y2 passes through the bridge 1 without any limitation, and as shown by the arrow Y3. It is sent to the transmission line 2b. As a result, the station 3b broadcasts all LLs.
A C frame will be received. The broadcast LLC frame sent from the station 3b also passes through the bridge 1 and is sent to the transmission line 2a.

On the other hand, the state shown in FIG. 6B is a state in which the number of broadcast LLC frames on the transmission line 2a is large. When the count number of the broadcast LLC frame per fixed time becomes larger than a certain value, the broadcast LLC frame sent from the station 3a as indicated by the arrow Y2 is sent to the transmission line 2a, but to the transmission line 2b. The transmission of the broadcast LLC frame is restricted in bridge 1.

In this state, if the broadcast LLC frame is relayed, the broadcast storm generated on one transmission path is relayed, and the broadcast storm spreads over the entire transmission path. When a broadcast storm occurs, the number of broadcast LLC frames increases abnormally and interrupts normal communication.
Some stations stall.

Therefore, in this bridge 1, the simultaneous broadcast LL
By controlling the parameter of the talk holding time according to the occurrence frequency of the C frame to control the forwarding amount of the frame, the broadcast storm and the excessive traffic increase are prevented.

In the above first and second embodiments, the case where two transmission lines are relayed has been described.
Even when three or more transmission lines are connected, it is clear that the relay operation of the broadcast frame can be limited by using the bridge of this embodiment.

The present invention may further have the following aspects in connection with the description of the claims.

(1) The first and second networks are token ring networks, and the relay control means counts the number of the broadcast frames per fixed time, and the relay control means according to the count value. The traffic control bridge according to claim 1, further comprising token holding time control means for increasing / decreasing a token holding time in the own bridge.

(2) The first and second networks are token ring networks, the relay control means counts the number of the broadcast frames per fixed time, and the count value is a predetermined value. The traffic control bridge according to claim 1, further comprising token holding time control means for reducing the token holding time in the own bridge when it becomes larger.

(3) The first and second networks are token ring networks, the relay control means counts the number of the broadcast frames per fixed time, and the count value is a predetermined value. The traffic control bridge according to claim 1, further comprising token holding time control means for increasing the token holding time in the own bridge when it becomes smaller than the predetermined value after becoming larger.

[0055]

As described above, according to the present invention, when the number of broadcast frames per fixed time exceeds a predetermined value, the relay operation between the networks is limited to increase the traffic or broadcast storm. This has the effect of preventing a failure of the transmission line due to the above.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a communication system including a traffic control bridge and a bus network according to a first embodiment of the present invention, in which (a) shows a state in which relay of a broadcast frame is not restricted. 9B shows a state in which relay of the broadcast frame is restricted.

FIG. 2 is a block diagram showing an internal configuration example of a traffic control bridge according to the first embodiment of the present invention.

FIG. 3 is a schematic diagram showing an example of a MAC address system in a CSMA / CD network.

FIG. 4 is a block diagram showing a configuration of a communication system including a traffic control bridge and a token ring type network according to a second embodiment of the present invention, in which (a) does not limit relay of a broadcast frame. Indicates
(B) shows a state in which relaying of broadcast frames is restricted.

FIG. 5 is a block diagram showing an internal configuration example of a traffic control bridge according to a second embodiment of the present invention.

FIG. 6 is a schematic diagram showing an example of a MAC address system in a token ring network.

[Explanation of symbols]

1 bridge 2a, 2b bus type network 3a, 3b station 11 CSMA / CD bridge relay processing section 12a, 12b CSMA / CD transmission section 13a, 13b CSMA / CD reception section 14a, 14b, 114a, 114b simultaneous broadcast counting section 20a, 20b Token ring type network 111 Token ring bridge relay processing unit 112a, 112b Token ring transmitting unit 113a, 113b Token ring receiving unit

Claims (5)

[Claims] 1. A bridge that is connected to first and second networks and that performs a relay operation for relaying a broadcast frame from the first network to the second network, wherein A traffic control bridge, comprising: relay control means for limiting the relay operation when the number of broadcast frames exceeds a predetermined value. 2. The relay control means includes a count means for counting the number of the broadcast frames per fixed time, and a relay disconnection means for disconnecting the relay when the count value exceeds a predetermined value. The traffic control bridge according to claim 1, comprising: 3. The traffic control bridge according to claim 1, wherein the first and second networks are bus-type networks. 4. The traffic control bridge according to claim 1, wherein the first and second networks are ring networks. 5. The traffic control bridge according to claim 4, wherein the ring network is a token ring network, and the frame is transmitted by a token.