JP3074806B2 - Signal channel selection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an asynchronous transfer mode (AT).
The present invention relates to a signal channel selection method for selecting a signal channel between adjacent stations among switching signal systems employing a multiplexing method called M).

[0002]

2. Description of the Related Art Heretofore, this type of signal channel selection system is based on a control signal for call control which is set between exchanges.
A so-called fixed channel allocation scheme has been proposed in which a virtual channel number ( VCI ) for a signal channel through which a signal flows is determined in advance and fixedly used.

[0003]

The above-mentioned signal channel selection method is a fixed channel allocation method, and since the signal channels between adjacent stations of all ports in the network are fixed, the VCI value in the signal cell is fixed. There is a drawback that when the data is destroyed during transfer and has a different value, signals cannot be transmitted and received between adjacent stations at all.

[0004] It is an object of the present invention to overcome the above-mentioned drawbacks by providing each exchange with a means for transferring and processing all received cells for which no output channel has been set to signal processing means and detecting non-delivery of signals. It is an object of the present invention to provide a signal channel selection method for eliminating the problem.

[0005]

The basic structure of a signal channel selection system according to the present invention is a signal channel selection system for selecting a signal channel set between exchanges employing a multiplexing system based on ATM (Asynchronous Transfer Mode). The exchange includes, in a conversion table in a header conversion unit provided between each input port and a switch unit, an authentication bit area in addition to an output channel number area indexed by a reception virtual channel number included in a reception cell. If the authentication bit indexed by the reception virtual channel number is not authenticated, the received cell is regarded as an emergency signal cell and transferred from the header conversion unit to the signal processing unit. When the transmission channel is analyzed and authenticated as a signal, this transmission channel is regarded as a normal signal channel and the corresponding authentication is performed in the conversion table. Having means for the bit to "true".

One specific configuration added to the above basic configuration is that after the exchange establishes the normal signal channel for the emergency signaling cell, a predetermined signal is periodically transmitted from the originating exchange to this channel. A means for transmitting a cell and detecting the normal signal channel as a failure when the receiving exchange cannot receive the signal cell at regular intervals, and executing a signal channel selection process again.

[0007]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention.

As shown in FIG. 1A, an originating exchange 10
Is connected to the destination exchange 20 by a multiplex line 40 by ATM (asynchronous transfer mode).

The originating exchange 10 connects a communication path for each call from the switch section 11 to the multiplexing line 40 via the signal cell insertion section 14, while the communication processing section 12 connects the signal cell insertion section 1.
4 to connect the signal channels.

[0010] The signal channel on the multiplexing line 40 is formed of signal cells to which one preset virtual channel number is assigned. This cell is generated by the signal cell insertion unit 14.

The destination exchange 20 analyzes the cells received by the header converter 21 and distributes the received cells to the signal processor 22 and the switch 24.

The header conversion section 21 has a conversion table 30. The conversion table 30 has an output channel number 32 and an authentication bit 33 in an area corresponding to a reception virtual channel number (VCI) 31.

Each of the signal processing unit 12 of the originating exchange 10 and the signal processing unit 22 of the destination exchange 20 has heartbeat circuits 13 and 23, and monitors the line.

The header conversion unit 21 of the destination exchange 20 has a conversion table 30.

FIG. 1B is a block diagram showing an example of the conversion table 30. As shown, the conversion table 30 stores a virtual channel number (VC
I) has an area of an output channel number 32 and an authentication bit 33 corresponding to 31.

The area of the output side channel number 32 is a physical number of the output port and a virtual channel number on the output port. For the inter-station signal, a route instruction to the signal processing unit 22 or a control unit (not shown) is recorded.

The area of the authentication bit 33 is stored in the signal processing unit 22.
, Authenticates the received cell as a user information channel or a normal signal, receives this notification, and records “true” in a position corresponding to the received virtual channel number (VCI).

When the authentication bit 33 is “ false ” other than “true”, the header conversion unit 21 transfers the received cell to the signal processing unit 22.

Therefore, when a normal signal channel is faulty,
Or, at the time of initial startup when the normal channel number is undecided,
Since the authentication bit 33 is “ false ”, when the received normal signal cell is determined by the signal processing unit 22 to be a normal signal, the conversion table 30 is notified and the authentication bit 33 is
Change " false " to "true".

As described above, any virtual channel number with the authentication bit " false " can be used as an emergency signal channel, so that if a normal signal can be received, a new normal signal channel can be set.

When the established normal signal channel delays the reception of the normal signal due to some trouble, the signal processing units 12 and 22 have heartbeat circuits 13 and 23 for early detection. The heartbeat circuits 13 and 23 periodically transmit signal cells from the originating heartbeat circuit 13 according to a predetermined virtual channel number (VCI) of the multiplexing line 40. When a specific signal cell cannot be received, a failure of the normal signal channel is detected and predetermined operation processing is executed.

[0022]

As described above, according to the present invention, the authentication bit "true" is recorded in the virtual channel by normal use,
The received virtual channel is “ false ” other than the authentication bit “true”
When one of the virtual channels with the authentication bit “ false ” is selected and converted to the authentication bit “true” and all the unauthenticated virtual channels can be used as emergency channels, the normal signal channel can be used. In addition to being able to change the number, there is an effect that a separate signal channel can be set even if a specific virtual channel number becomes an obstacle.

Further, by periodically transmitting a signal cell to a normal signal channel having a specific virtual channel number, it is possible to detect an abnormality even if a specific channel becomes faulty.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a signal channel selection method according to the present invention.

[Explanation of symbols]

10, 20 Switch 11, 24 Switch 12, 22 Signal processing 13, 23 Heartbeat circuit 14 Signal cell insertion 21 Header conversion 30 Conversion table 31 Virtual channel number (V
CI) 32 Output channel number 33 Authentication bit

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H04L 12/56 H04L 12/28

Claims (1)

(57) [Claims] 1. A system for controlling a call which is set between exchanges adopting an ATM (Asynchronous Transfer Mode) multiplexing system.
In a signal channel selection method for selecting a signal channel through which a control signal flows , the switching unit indexes a conversion table in a header conversion unit installed between each input port and a switch unit with a reception virtual channel number included in a reception cell. An authentication bit area is provided in addition to the output side channel number area to be authenticated. If the authentication bit indexed by the reception virtual channel number is unauthenticated, the received cell is regarded as an emergency signal cell and a signal is sent from the header conversion unit. Transfer to processing section,
When the signal processing unit analyzes the emergency signal cell and authenticates the signal, the transmission channel is set as a normal signal channel and the corresponding authentication bit in the conversion table is set to “true” . The normal signal
After establishing the channel, the originating exchange
Sends a predetermined signal cell periodically from the
When the receiving exchange cannot receive the signal,
Detects a channel as a fault and selects a signal channel again.
A signal channel selection method, comprising means for executing a selection process .