JPH03280638A - Remote bridge - Google Patents

Abstract

PURPOSE:To improve the utilization efficiency of the installation by detecting the communication state of a normal line, instructing the inhibition of frame transmission to a remote bridge connected to a same standby line in the case of the normal communication state and instructing the release of the inhibition of frame transmission in the case of a fault transmission state. CONSTITUTION:The system is provided with a means detecting whether the communication through a usual line is normal or not, instructing the inhibition of frame transmission in the case of the normal transmission state to remote bridges 20-1, 20-2 connected to a same standby line 22-2 and instructing the release of the inhibition of frame transmission in the case of the abnormal transmission state. Thus, when the communication through a channel of the normal line is implemented normally, no frame is sent from a LAN to the standby line 22-2 and only when the communication through the normal line is abnormal, the transmission/reception management with the LAN according to the spanning tree algorithm. Thus, the utilization efficiency of the installation relating to the use of the standby line 22-2 is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Fields] The present invention is directed to a wide area network (hereinafter referred to as WAN) in which a local area network (hereinafter referred to as LAN) is double-connected via a remote line. This invention relates to improvements to remote bridges used for connection with and frame transmission/reception management.

[Prior Art] Various connections between LANs using bridges are illustrated in FIGS. 4 to 7. In particular, Figures 6 and 7 show connections between LANs via remote lines using bridges.
It is called WAN.

First, in Figure 4, LAN10 and LAN12 are connected to bridge 1.
A configuration connected by 4 is shown.

In this configuration, LANs 10 and 12, each including a predetermined number of stations 16 and 18, are bridges]
4 ports 14a or 14b, respectively. That is, by allowing frame transmission and reception between the LANs 10 and 12 by the bridge 14, a communication path based on the ISO O12 MAC layer level is provided.

Next, in the LAN-to-LAN connection by bridges shown in FIG. 5, bridges 14 and 20 are provided, both of which operate according to the Spanning Tree algorithm detailed in IEEE802.1D.

For example, if we consider that bridges 14 and 20 in this figure provide communication channels at the same time, then LAN10 and
A loop-shaped communication path is configured between 2, and the LAN
In this case, it becomes difficult to perform communication normally by transmitting frames from 10 or 12.

The spanning tree algorithm is an algorithm that cuts off the communication path related to the bridge 14 or 20 in this loop and prevents the formation of a looped communication path.

Therefore, if a communication path using the bridge 14 is configured, the communication path using the bridge 20 is cut off, and communication is performed only through the communication path related to the bridge 14. On the other hand, in this state, an abnormality occurs in the communication path by the bridge 14,
If such a communication path becomes unavailable, a communication path is formed by the bridge 20 and a new communication path is provided.

In this way, by the Svanning Tree algorithm,
Even if equipment related to the connection between LANs 10 and 12 breaks down, the reliability in maintaining normal communication between LANs 10 and 12 increases, making it possible to maintain normal communication compared to the LAN indirect/indirect shown in Figure 4. become.

FIG. 6 shows the configuration of the WAN.

In this figure, LAN l0 is connected to port 14-1a of bridge 14-1, and port 14-1b of this bridge 14-1 is connected to port 14-2a of another bridge 14-2 via remote line 22. has been done. Furthermore, the port 14-2b of the bridge 14-2 is connected to the LAN 12
It is connected to the.

In the configuration shown in this figure, bridges 14-1 and 14-2 are called remote bridges because they are connected to remote line 22.

In the configuration shown in FIG. 4 or 5, the ports of bridge 14 or 20 are connected to LAN 10 or 12, but in this figure remote bridge 1
14-1b and 14 of ports 4-1 and 14-2
-2a is connected to the remote line 22. In other words, in the WAN shown in this figure, the remote line 22 is treated as a type of LAN.

FIG. 7 shows a configuration in which LANs 10 and 12 are connected by a remote bridge using the above-mentioned Subhangulli algorithm.

That is, in this figure, in addition to the remote bridges 14-1 and 14-2 connected to each other by the remote line 22-1 as in FIG. Bridges 20-1 and 20-2 are shown.

In the case of the WAN shown in this figure, one remote line 2
2-1 is called a normal line, and the other remote line 22-2 is called a standby line.

In other words, when a communication path related to remote bridges 14-1 and 14-2 is formed according to the spanning grid algorithm, one of remote bridges 20-1 or 20-2 connected to standby line 22-2 Transmission and reception of frames by one side is stopped.

On the other hand, remote bridge 14-1, normal line 22-1
If an abnormality occurs in the equipment related to the communication path by the remote bridge 14-2, the remote bridge 20-1 or 20-2, which had stopped transmitting and receiving frames, allows the transmitting and receiving of frames, and the standby line 22- A communication path based on 2 will be constructed. Therefore, in a WAN as shown in FIG. 7, reliability against equipment failure is maintained by the spanning tree algorithm, and the LAN l0 installed remotely is and 12 will be connected and communication will take place.

FIG. 8 shows the configuration of a remote bridge used in the WAN shown in FIG. 7. The remote bridge 20-1 shown in this figure has port 2 on the LAN10 side.
0-1g and boat 2O-1b on the standby line 222 side,
The module that drives the Spanning Tree algorithm (
(hereinafter referred to as STA) 20-1c. Further, the boats 2O-1a and 2O-1b each include a DL20-1d and a DL20-1e, which are modules that transmit and receive frames.

First, a case where the normal line 22-1 is operating normally will be described.

In this case, 5TA20-IC closes the communication path of DL20-1e. In this case, LAN10 or standby line 2
Even if a frame is sent from DL 2-2, DL 20-16 does not transmit or receive the frame, and therefore a communication path related to standby line 22-2 is not formed.

Therefore, in this case, communication between LANs 10 and 12 is performed only through the communication path related to the normal line 22-1.

When a device abnormality or the like occurs in the communication path related to the normal line 22-1, the 5TA 20-1c detects this abnormality and opens the communication path of the DL 20-1e.

In this case, when a frame is transmitted from LAN10, DL
20-1d receives this, and the DL 20-1e further transmits this frame onto the standby line 22-2. When a frame is transmitted from the standby line 22-2, the DL 20-1e receives it and sends it to the DL 20-1e.
1d, the frame will be transmitted to the LAN 10.

In this way, the opening and closing of the DL communication path is under the control of the STA. Although the case where the communication path is closed at the remote bridge 20-1 on the standby line side is shown here, the same applies to the case where the communication path is closed at the remote bridge 20-2.

Normally, in the Svanning Tree algorithm, the remote bridge 20-1 related to the connection with the standby line 22-2
and 20-2, communication channel opening/closing control is performed for only one of them. That is, in order to avoid forming a loop communication path between LANs 10 and 12, remote bridge 22-1 related to connection with standby line 22-2 must be
Since it is sufficient to close only one of the communication paths among the communication lines 22-2 and 22-2, if the communication path related to the normal line 22-1 is operating normally, the communication path only for the remote bridge 201 is closed, for example.

[Problem to be solved by the invention] However, in the conventional WAN, among the two types of remote lines, the standby line is not involved in normal communication, but the remote line related to the connection with the standby line Frames are sent from one of the bridges onto the standby line. In other words, only one of the remote bridges installed at both ends of the standby line closes the communication path when the communication path related to the normal line is communicating normally; The communication channel is not closed, and as a result, frames flow onto the standby line.

Generally, WAN services are billed on a time-by-hour or transmission-capacity basis, so sending frames onto a standby line adds line usage charges, which is extremely uneconomical for WAN users. That will happen. Furthermore, since there are generally no stations on the standby line, there is no need to send frames.

The present invention has been made with the aim of solving these problems, and it is an object of the present invention to prevent communication on the standby line when the communication path related to the normal line is functioning normally and communication is being performed normally. The purpose is to provide a remote bridge that makes it possible to prohibit the sending of frames.

[Means for Solving the Problems] In order to achieve such an object, the present invention detects whether the communication being carried out on the normal line is in a normal state or an abnormal state, and connects to the same standby line. Instructs the remote bridge to prohibit frame transmission in normal conditions,
The present invention is characterized by comprising means for instructing a means for instructing the prohibition of the frame state to be canceled in the case of an abnormal state.

[Operation] In the remote bridge of the present invention, it is detected whether the communication performed through the normal line is in a normal state or an abnormal state. As a result, if the status is normal, remote bridges connected to the same standby line are instructed to prohibit sending frames. Conversely, if an abnormal state occurs, a remote bridge connected to the same standby line is instructed to release the inhibition of frame transmission. As a result, when communication through the communication path related to the normal line is performed normally, frames are not sent from the LAN to the standby line, and when communication performed through the normal line is abnormal. LAN only according to the spanning tree algorithm
The transmission and reception of frames to and from the network is managed.

[Example] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

Note that the same components as those of the conventional example shown in FIGS. 4 to 8 are denoted by the same reference numerals, and the explanation thereof will be omitted.

FIG. 1 shows the configuration of a remote bridge according to an embodiment of the present invention.

A remote bridge 20-1 shown in this figure is provided with an instruction module 2O-1f according to a feature of the present invention.

Next, the operation of this embodiment will be explained.

Figure 2 shows the operation of the standby line when the normal line 22-1 is operating normally. Only such DLs 22-1e and 22-2d are shown.

In this case, as shown in FIG.
Obtain information indicating the normal operating state of the communication path related to -1.

Next, as shown in FIG. 2(b), the instruction module 2O-1f instructs the DL 20-1e to send a Disable instruction frame FD onto the standby line 22-2. On the other hand, the instruction module 24-1 is 5TA20-
Dlsable Port is issued to 1c.

Here, Disable Port is a type of management operation for the 5TA20-IC by the instruction module 2O-1f, and is an instruction to remove the DL20-16 from the control of the 5TA20-10 and forcibly close the communication path. .

The Disable instruction frame FD sent onto the standby line 22-2 is sent to the remote bridge 22- connected to the other end of the standby line 22-2, as shown in FIG. 2(C).
2, and the instruction module 20-2f of this remote bridge 20-2 is notified of the reception.

Then, as shown in FIG. 2(d), D45abl
Instruction module 2O that learned of the reception of the e instruction frame FD
-2f is Disable for 5TA20-2C
Emit a port. As a result, remote bridge 20-
2 DL22-2d is no longer under the control of 5TA(7), the communication path is forcibly closed, and frame transmission from LANI2 to standby line 22-2 via remote bridge 20-2 is prohibited.

FIG. 3 shows the operation of the standby line when an abnormality occurs in the communication path related to the normal line 22-1 and communication through this communication path is not performed normally.

In this case, first, as shown in FIG. 3(a), 5
The instruction module 201f detects from the TA 20-1c that the normal line 22-1 is in an abnormal operating state.

Next, the instruction module 2O-1f sends the Enable instruction frame FE to the standby line 22-2 via the DL20-16.
At the same time, send Enable to 5TA20-1c.
e Port. Enable Port is D
Contrary to the isable port, DL20-1e is 5T
This is an instruction to return it to the control of A20-1c. 5TA2
．． As a result of the operation of DL 20-1c, the communication path of DL 20-1e is opened, and frames can be sent from LAN 10 via remote bridge 20-1. In addition, the above-mentioned Disa
ble and Enab I e instruction frame sending and FE
are frames that can be distinguished from other data frames by both DL20-16 and 2O-2d.

Next, as shown in FIG. 3(c), the standby line 22-
Enable instruction frame FE on 2 is DL20-2d
The instruction module 20-2f of the remote bridge 2-2 is notified of the reception.

In response to this, the instruction module 2O-2f operates as shown in FIG.
), set the Enable Port to 5TA
20-2c, DL20-2d to 5TA20-2c
Return to control.

As a result, LAN1 via remote bridge 20-2
2 becomes possible to transmit and receive frames to and from the standby line 22-2.

Here, the same discussion can be made even if remote bridge 20-1 and remote bridge 20-2 are replaced.

As described above, according to this embodiment, when the communication path related to the normal line 221 is operating normally, the standby line 22-
Frame transmission/reception via the remote bridges 20-1 and 20-2 related to No. 2 is prohibited, and unnecessary charges associated with frame transmission on the standby line 22-2 are prevented.

In addition, an abnormality occurred in the communication path related to the normal line 22-1,
If communication is not performed normally, the standby line 22
-2 communication path is formed, and this communication path connects the LAN.
It becomes possible to communicate between 10 and 12.

In the above description, there are only two remote lines, but there may be three or more.

[Effects of the Invention] As explained above, according to the present invention, even when communication is normally performed through the communication path related to the normal line, frame transmission to the standby line is prohibited, and transmission of frames to the standby line is prohibited. The efficiency of equipment used will improve.

Furthermore, charges associated with sending frames onto the standby line are prevented, and the economic burden on WAN-related service users is reduced.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a remote bridge according to an embodiment of the present invention, and FIG. 2 is an operation diagram showing the normal operation of a normal line in this embodiment. a) is an operation diagram when the operating state of the normal line is detected, and FIG. 2(b) is a Disable instruction frame and a Disable instruction frame by the instruction module.
FIG. 2(c) is an operational diagram when the other instruction module receives a Disable instruction frame. FIG. 2(d) is an operational diagram when the other instruction module sends a Disable Port. Figure 3 is
3(a) is an operational diagram showing the operation when the normal line is abnormal in this embodiment, FIG. 3(a) is an operational diagram when the operating state of the normal line is detected, and FIG.
FIG. 3(c)f; is a diagram of the operation when the other instruction module receives the Enable instruction frame; FIG. 3(d) is the operation diagram when the other instruction module sends the Enable instruction frame.
Operation diagram when sending Port, Figure 4 is a LAN connection diagram using a bridge, Figure 5 is a LAN connection diagram using multiple bridges.
Figure 6 is a LAN-to-LAN connection diagram via a remote line using a conventional remote bridge. Figure 7 is a LAN-to-LAN connection diagram via a plurality of remote lines by a conventional remote bridge. 7 is a configuration diagram of a remote bridge in the conventional example shown in FIG. 7. FIG. 10.12 ... Local area network 1
4-1.14-2.20-1.20-2... Remote bridge 2O-IC920-20... Spanning tree algorithm execution module

Claims (1)

[Claims] In order to connect a local area network connected by a normal line that is a remote line to a standby line that is another remote line, the standby line and the local area network are provided between the standby line and the local area network, and according to a spanning tree algorithm. A remote bridge that manages frame transmission and reception between a local area network and a remote line detects whether the communication performed on the normal line is normal or abnormal, and then sends a message to the remote bridge connected to the same standby line. A remote bridge characterized by comprising means for instructing prohibition of frame transmission in a normal state and instructing cancellation of prohibition of frame transmission in an abnormal state.