JPH077992B2 - Signal link controller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a signal link control device, and in particular to CC
The present invention relates to a level 2 signal link control device of common line signaling system NO7 recommended by ITT.

[Conventional technology]

In order to meet the demand for increasingly sophisticated and diversified communication networks with the progress of the information society, two technical pillars of future communication network development are digitalization of communication networks and control of stored programs. It is said. As a result, telephone services will become more economical and sophisticated, and non-telephone services will be provided, and the communication network will develop toward ISDN.

The common line signaling system is an information transfer means in the flow of the above-mentioned technology, which connects the control system devices of the exchanges under the control of stored programs with a data link to maximize the capacity of the “network”. It is provided. This common line signaling system is a signaling system in which signals are transmitted and received through a dedicated signal line different from the communication line, and this signal line is commonly used by many communication lines.

In addition, a new signaling system that replaces the conventional common line signaling system is required in order to deal with the digitization of the "network" and the introduction of integrated services, and the 7th from CCITT (International Telegraph and Telephone Consultative Committee) Recommended as a signaling system. this
It is called NO7 common line signaling system.

Generally, when two exchanges send and receive a signal, a communication procedure (protocol) is previously defined between the exchanges, and the signal is sent and received according to the procedure. In the common line signaling system NO7, four hierarchies (levels) are adopted as protocols.

Level 1 is the most basic hierarchy that matches the electrical / physical conditions (communication speed, transmission code format, transmission method, etc.) of the signal transfer medium.

Level 2 is also called a signal link level, and is a layer having an error check and a retransmission function for transferring a signal unit to an adjacent exchange through a signal line without error. A link is a term indicating a signal line used in level 2, and is a signal line in which a level 2 function is added to a physical line. As will be described later, the signaling link control device of the present invention is a device at this level 2.

Level 3 is also called a network level, and is a layer having a function of combining signaling links and delivering a signaling message to a target exchange.

Level 4 is a layer also called a user part, which is a communication part provided for transmitting / receiving signals. At level 4, there are a plurality of communication roles (users) depending on the functions of signals handled such as telephone and facsimile communication.

By the way, the role of the signal link control of the common line signaling system NO7 is to transfer the signaling message to the partner station via the signal data link without error. for that reason,
In addition to the signal information received from the higher level 3, the signal unit also contains level 2 information required to guarantee the normality of the signal information.

The signal units handled by the common line signaling system can be classified into three types: fill-in signal units (FISU), link status signal units (LSSU), and significant signal units (MSU).

The FISU is created and used at level 2 as a dummy signal for suppressing the signal delay within a fixed time and a verification end notification signal of the signal data link in the initial setting of the signal link. LSSU is a link signal unit made at level 2 such as error control and signal synchronization as signal transfer information for guaranteeing normal operation of the signal link. It is used for initial setting status display, signal line verification, It is used to notify the other side of abnormalities and congestion.

The MSU is a signal unit that carries information such as labels and signal types used for signal route selection (routing) between the originating and destination stations of signals as raw information created by the telephone user section. Signal network management signal unit, signal There are network test / maintenance signal units, telephone connection signal units, etc.

In addition, if an error is detected using the CK code for error detection and a transmission error is recognized, the signal cannot be used and is discarded, and after that signal, all signals are retransmitted to correct the error. The method of doing is adopted.

For error correction, the number (forward sequence number: FSN) given to the transmission signal unit in order of the transmission signal unit and the FSN of the reception signal unit that the reception signal returns to the transmission signal side for confirmation of delivery
(Reverse sequence number: BSN) and forward and reverse status indicator bits (FIB, BIB) are used along with FSN, BSN to indicate retransmission activation and request.

Conventionally, an m + n configuration has been adopted as the redundant configuration for the input / output circuit of the level 2 termination circuit of the signal link device used in this type of NO7 common line signal system. That is, a structure having n spare circuits for the currently used m circuits has been adopted.

However, the level 2 connected to the level 2 termination circuit of the game
The terminating circuit always sends and receives data, and even when there is no data to send and receive, the FISU is sent and received to check the normality of the data link, so the terminating circuit cannot be easily switched. , The level 2 termination circuit was switched after disconnecting the data link.

[Problems to be Solved by the Invention]

By the way, the above-mentioned conventional level 2 termination circuit switching method has the following drawbacks because the level 2 termination circuit is switched after disconnecting the data link.

Each time the level 2 termination circuit is switched, it is necessary to execute the signal link switching procedure in the signal network to divert the signal traffic to another detour route, which has a drawback that it affects the opposite device.

[Means for Solving the Problems]

The present invention has a function of stopping reception of a significant signal unit (MSU) received from an in-service signal link, a forward sequence number (FSN) at the time of stop of reception, a forward status indication bit (FIB), and a backward direction. A function to read out the sequence number (BSN) and backward direction indication bit (BIB), and to set any forward sequence number, forward state indication bit, backward sequence number and backward state indication bit as the in-service status. A level 2 termination circuit having a function of restarting operation, and a switching circuit capable of controlling the communication path independently on the transmission side and the reception side of the signal link and capable of one-to-many connection, and a signal in service This switching circuit allows the receiving side path circuit to perform a spare level 2 termination circuit without affecting the connection between the link and the working level 2 termination circuit that is in service. Connected to, the level of working 2
The reception of the significant signal unit of the termination circuit is stopped, and the forward sequence number, the forward state display bit, the backward sequence number, and the backward state display bit when the reception is stopped are read, and these forward sequence number and forward state are read. After writing the display bit, the reverse sequence number, and the reverse status indication bit to the spare level 2 termination circuit and restarting the operation, the transmission side communication path of the spare level 2 termination circuit is switched by this switching circuit. It is a signal link control device which is connected to a signal link which is in service and is used as a current service.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a signaling link control device showing an embodiment of the present invention.

The signal from the level 2 termination circuit 1 of the game is the signal link 2
Is connected to the switching circuit 4 via the communication path 5, is connected to the communication path 5 via the communication path 12 set on the switching circuit 4, and is further connected to the working first level 2 termination circuit 9.

On the contrary, the signal from the working first level 2 termination circuit 9 is
It is connected to the level 2 terminating circuit 1 of the game via the communication path 6, the communication path 13 on the switching circuit, and the signal link 3.

During the in-service, a message unit or FISU is transmitted and received between the level 2 termination circuit 1 of the opposite station and the working first level 2 termination circuit 9 via the connected communication path.

In the state where the communication path between the level 2 termination circuit 1 for the game and the first level 2 termination circuit 9 for use is connected, the communication path 14 on the switching circuit is connected, and from the level 2 termination circuit 1 for the game. Of the second signal as a backup signal via the communication path 14 and the communication path 7.
Connected to the level 2 termination circuit 10 of.

Thereafter, the data transmission / reception request from the upper level termination circuit 11 to the working first level 2 termination circuit 9 is stopped. next,
After all the transmission data in the first level 2 termination circuit 9 are exhausted, the first level 2 termination circuit 9 is instructed to stop receiving the message unit (MUS) from the level 2 termination circuit 1 of the game. .

After stopping the reception of the message unit, the higher-level termination circuit 11 sends a forward sequence number (FSN), a forward status indication bit (FIB), a backward sequence number (BSN), from the first level 2 termination circuit 9. Reverse status indicator bit (B
IB) is read out, written in the spare second level 2 termination circuit 10 and the second level 2 termination circuit is instructed to resume the operation in the in-service state.

The spare second level 2 termination circuit 10 starts its operation in the in-service state, receives the signal from the level 2 termination circuit 1 of the game, and outputs a response to the communication path 8.

By receiving the same signal as the signal received by the working first level 2 termination circuit, which is opposed to the level 2 termination circuit 1 of the opposite station, the second in-service state is maintained. By switching the output of the level 2 termination circuit 10 to the output of the first level 2 termination circuit 9 by the switching circuit 4, the output of the second level 2 termination circuit 10 is the speech path 8, the speech path 15, the signal link 3 Start level 2 termination of the game via
Connected to.

After that, the upper level termination circuit 11 uses the second level 2 termination circuit 10 as an active circuit.

〔The invention's effect〕

As described above, the present invention connects only the receiving side of the spare second level 2 termination circuit to the in-service signal link and stops the reception of the message unit of the working first level 2 termination circuit. , Level 2 sequence number (FS
N, BSN) and status indication bits (FIB, BIB) are the first active
Can be read from the level 2 termination circuit, written to the spare second level 2 termination circuit, restart the operation of the spare level 2 termination circuit, and connect the output of the spare level 2 termination circuit to the signal link.

By doing this, it is possible to switch signaling terminals without disconnecting the signaling link, enabling diagnosis of the current signaling terminal and switching of signaling terminals within the same maintenance unit as the failure without affecting the game. The effect is that maintenance testability can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram of a signaling link control device showing an embodiment of the present invention. 1 ... Level 2 termination circuit for game, 2,3 ... Signal link, 4 ... Switching circuit, 5,6,7,8 ... Speech path, 9 ... Working first level 2 termination circuit, 10 ...... Spare second level 2 termination circuit, 11 …… Higher level termination circuit.

Claims (1)

[Claims] 1. A function of stopping reception of a significant signal unit received from an in-service signal link, a function of reading various error correction codes when reception is stopped, and a code corresponding to any of the various correction codes is written. First and second level 2 termination circuits having a function of restarting the operation as an in-service state, and a call path can be controlled independently for a transmission side signal link and a reception side signal link, and A switching circuit capable of connecting a plurality of own level 2 termination circuits to one opposite level 2 termination circuit, and a signal link in service and a first level 2 termination circuit in use in service The call circuit on the receiving side is connected to the second level 2 termination circuit through the switching circuit without affecting the connection with the significant signal unit of the working first level 2 termination circuit. After the reception is stopped, the various error correction codes at the time of the reception stop are read, the various error correction codes are written in the second level 2 termination circuit, and the operation is resumed in the in-service state, then the second level 2 A signal link control device, comprising: a control means for connecting the transmission side communication path of the terminating circuit to the signal link in service by the switching circuit and controlling the signal link to be used for the current service.