JPH06339189A - Path bypass system in time division multiplexer network - Google Patents

Abstract

PURPOSE:To reduce path connection information to be registered by registering a network operation form in the normal state as a basic operation information so as to define path bypass operation that takes occurrence of a fault of a high speed line and its restoration into account. CONSTITUTION:A control section 1 registers and stores path connection information equivalent to the basic operation information to a write/read enable storage section 2 and similarly registers an instruction set for bypass operation on the occurrence of a fault in advance thereto. When one of high speed line interface sections 7 detects a fault of a high speed line. the detection of the line fault is informed to the control section 1 and the control section 1 specifies a line on which the fault takes place and reads a bypass operation instruction from the storage section 3 to rewrite the setting of a path connection setting table 4. When the high speed line interface section 4 detects the restoration of the high speed line, the interface section 7 informs the detection of line restoration to the control section 1 and the control section 1 reads a relating restoration operation instruction from the storage section 3 to rewrite the setting on the path connection setting table 4 and to restore the setting of the path.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for bypassing a path when a line failure occurs in a network composed of time division multiplexers.

[0002]

2. Description of the Related Art A network composed of a time division multiplexer increases transmission efficiency by accommodating a low speed line in a higher speed line by using a time division data transmission technique or a digital data compression technique, thereby reducing the line cost. To realize. However, when a failure occurs in a high-speed line, the range of its influence increases, which generally reduces the reliability of communication.

Therefore, in a network composed of a time division multiplexer, especially for a failure of a high-speed line, providing a means for complementing communication is a very important point in considering the reliability of the network.

The most reliable countermeasure against high-speed line failures is to duplicate each high-speed line between nodes, but the cost of high-speed lines doubles, so the cost reduction characteristic of the time-division multiplexer is introduced. The effect will be greatly impaired.

Therefore, a high-speed line is connected so as to secure at least two routes connected by a high-speed line between one node and another node in the network, and when a failure occurs in the high-speed line, the line is accommodated. The bypass is used to avoid the disconnection of communication.

[0006] As a method for quickly realizing the detour of the path, conventionally, time division multiplexing in which sets A and B of the connection states of the paths corresponding to the normal operation state and the detour operation state are installed in each node There is a method of registering in the device and operating on the A side during normal operation, and switching to the B side when a failure occurs on the high-speed line.

[0007]

However, assuming that failures of a plurality of high-speed lines overlap in time, the number of registrations of the set of connection information is 2 for n high-speed lines.
^{Since n} pieces are required, there is a problem that the limit of the number of high-speed line fault multiplexes that can be dealt with is low due to the limitation of the memory in the time division multiplexer.

Even if registration is successful, it is difficult to make a decision because it is necessary to consider the current failure state and the current connection state in order to determine which set of connection information to switch to when a failure occurs and at the time of restoration. There are also problems.

An object of the present invention is to reduce the amount of path connection information registered in each time division multiplexer.

[0010]

According to the path detouring method of the present invention, in a time division multiplexing device installed in each node, a basic operation aspect consisting of a set of all path connection information, a path connection deletion command statement, Path connection addition statement and conditional path connection deletion
The detour / recovery operation at the time of failure consisting of a set of additional command sentences "Delete path P ₂ and add path P ₃ if there is path P ₁ " is registered and stored in advance, and basic operation is performed in the initial normal times. Connect paths according to the plane, select the bypass operation at the time of failure to realize the bypass of the corresponding line when a high-speed line failure occurs between nodes, delete / add the path according to the command statement, and collect the connection information of the new path Is generated, and switching to the desired path detour operation mode is realized.

[0011]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a block diagram of a time division multiplexing apparatus showing an embodiment of the system of the present invention. This time division multiplexing apparatus includes a control unit 1, a storage unit 2, a storage unit 3, a path connection setting table 4, a time division switch unit 5, a low speed line interface unit 6, and a high speed line interface unit 7.
And a signal line 8.

From the control unit 1, the path connection information corresponding to the basic operation side is registered in the writable and readable storage unit 2,
The instruction set for the bypass operation at the time of failure is stored in advance in the storage unit 3 in the same manner.

The control unit 1 selects a basic operation plane from the storage unit 2 and writes it in the path connection setting table 4 in the initial normal state. The time division switch unit 5 connects the channel of the low speed line interface unit 6 and the specific time slot of the high speed line interface unit 7 according to the value of the path connection setting table 4. Further, in order to realize a node relay path, specific time slots are connected to each other between different lines of the high speed line interface unit 7.

When one of the high-speed line interface units 7 detects an abnormality in the high-speed line, the control unit 1 is notified of the line failure detection via the signal line 8, and the control unit 1 identifies and stores the line in which the failure has occurred. The corresponding detour operation command is read from the unit 3 and the setting on the path connection setting table 4 is rewritten to complete the switching to the setting detouring the faulty line.

When the high-speed line interface section 7 detects the restoration of the high-speed line, it notifies the control section 1 of the line restoration detection through the signal line 8, and the control section 1 identifies the restored line and stores it in the storage section 3. The corresponding recovery operation command is read and the setting on the path connection setting table 4 is rewritten to restore the detoured path setting.

FIG. 2 is a schematic diagram showing an example of a set of detour operation instructions and transitions of path connection states in the present invention.

This example includes a case in which the detour-destination line has a further failure. In the figure, for example, P (a-A) is a and A.
Represents a path connecting between. Path connection delete command is -P
n, the path connection addition command statement is represented by + Pn, and the conditional path connection deletion / addition command statement is represented by ifPm → -Pn, + Pp.

By adjusting the conditional path connection deletion / addition command, it becomes possible to make a transition with a set of one detour operation command for the event of line failure or recovery regardless of the path connection state up to that point.

[0020]

As described above, according to the present invention, by registering the normal network operation mode as a basic operation plane and defining the path detour operation assuming the occurrence and recovery of a high-speed line failure, It is sufficient to register at least n detour operations and n recovery operations for n high-speed line failures, which has the effect of reducing the path connection information to be registered. Further, there is an advantage that the detour / recovery operation at the time of occurrence of a line failure and the recovery can be made to correspond one-to-one, and the switching operation can be easily selected.

[Brief description of drawings]

FIG. 1 is a block diagram of a time division multiplexing apparatus showing an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an example of a set of detour operation instructions and transition of a path connection state according to the present invention.

[Explanation of symbols]

 1 control unit 2 storage unit 4 path connection setting table 5 time division switch unit 6 low speed line interface unit 7 high speed line interface unit 8 signal line

Claims (2)

[Claims] 1. A set of connection information in a time division multiplexing apparatus installed in each node for forming a set of paths corresponding to an operation mode of a network is defined, and the connection information set is set for each operation mode. All paths are connected in a network in which operation plane numbers are registered and stored in each time division multiplexer, and the selection of the network operation mode is switched by specifying the operation plane number to each time division multiplexer. For each time-division multiplexing device, the basic operation aspect consisting of a set of information, and the failure detour / recovery operation consisting of a path connection deletion command statement, a path connection addition command statement, and a conditional path connection deletion / addition command statement Path detour method that realizes operation mode switching by registering and storing, selecting the appropriate failure detour / recovery operation at the time of line failure / recovery between nodes, and generating a new set of path connection information formula. 2. Correspondence between a line fault occurrence / restoration between nodes and a corresponding fault detour / restoration operation is registered in advance in each time division multiplexing device, and when the line fault is detected in the node. 2. The path detouring method according to claim 1, wherein the demultiplexing device selects the detour / recovery operation at the time of failure based on information on which line has failed / restored to perform detour / restoration.