JP2855065B2 - Rerouting method in private network using ISDN leased line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rerouting method in a private network constructed by a digital private branch exchange.

[0002]

2. Description of the Related Art FIG. 5 is a diagram showing an example of a conventional private network relaying system constructed with a dedicated line dedicated to a private network. A terminal (calling station) accommodated in an EPBX (station A) which is a digital electronic private branch exchange. Person) 10 is EPBX (station D)
This is an example of a case in which a connection operation is performed to a terminal (destination destination) 12 accommodated in a terminal.

[0003] An individual line dedicated line 2
1 to the EPBX (station B), and similarly to the EPBX (station C) via the dedicated dedicated line 22. At this time, as shown in the figure, if there is no obstacle to the other party's route at station C or if there is no alternate route during all talks, a call is lost due to busy tone (BT) connection.

[0004]

As described above, in the prior art, the EPBX (station B) has the EPBX despite the detour route 25 of the dedicated line or the dedicated line of the ISDN.
Since the transmission process is performed to (station C) and the partner route cannot be secured by EPBX (station C), there is a problem that an effective detour process is not performed.

[0005] That is, the dedicated leased line 25 is not used as an obstacle route between relay stations or as a bypass route during all calls, but as an EPBX.
At the time of connection processing to a terminal accommodated in (E station)
It was only used as a route for not relaying PBX (station C) and EPBX (station D). Therefore, the prior art private network lacked flexibility and was inconvenient.

The present invention is not limited to individual line dedicated lines,
The disadvantage that the route detour function is not effectively performed in a private network constructed with a dedicated line is eliminated, and an ISDN leased line that can effectively set a detour route in the event of a failure between relay stations or during all calls is used. private·
An object of the present invention is to provide a rerouting method in a network.

[0007]

According to the present invention, in order to solve the above-mentioned problems, a digital private branch exchange accommodating an ISDN leased line is provided with a means for identifying a reason information element of a disconnection message in the ISDN layer 3, and If there is a detour route in not only the station but also the relay station, detour processing is performed.

[0008]

According to the present invention, a second extension terminal accommodated in a first digital private branch exchange receives a second extension via a relay station.
In a rerouting method in a private network using an ISDN leased line for performing connection processing to a second extension terminal accommodated in a digital private branch exchange,
Call setup is performed between the digital private branch exchanges via the D channel of the ISDN line. When a disconnection message including the reason information of the ISDN layer 3 information element is received from the digital private branch exchange that has performed the call setup, the disconnection message is sent. The received digital private branch exchange determines whether or not there is a detour route. If there is a detour route, the digital private branch exchange releases the call with the digital exchange that sent the disconnection message, and also makes a new call on the detour route. Perform processing.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment of the rerouting method in the private network using the N dedicated line will be described in detail.

FIG. 2 shows an embodiment of a private network constructed with an ISDN leased line according to the present invention, in which an EPBX (station C) and an EPBX (EPBX) are used as in FIG. E) A case where an inter-station is in a trouble or all the lines are busy. In this embodiment, the trunk lines 1 to 5 between the stations use ISDN dedicated lines.

FIG. 3 shows an example of a normal sequence when there is no detour route in the ISDN leased line shown in FIG. Therefore, in this sequence example, when rerouting is not performed, that is, the EPBX (station B) shown in FIG.
An example of a connection process from the terminal 10 to the terminal 12 when there is no ISDN leased line 5 between EPBXs (stations E) is shown.

[0012] By a dial operation of a terminal (caller) 10 accommodated in the EPBX (station A), a call setup (SETUP) message is sent out via the ISDN leased line 1 and
Call setting acceptance from PBX (station B) (CALL_PROC)
Receive a message. Similarly, in the EPBX (station B), the connection destination number (called number) of the call setup (SETUP) message
And performs a calling operation via the ISDN leased line 2.

However, EPBX (station C)
The normal disconnect message (DISC) is sent to the EPBX because the relay route of (station E) is faulty or there is no alternate route due to the whole talk.
(Station B). EPBX (station B) is EPBX (station C)
It is determined whether there is a detour route in the same manner as described above. In this case, since there is no ISDN leased line 5, EPBX (station A)
Performs a disconnection sequence (DISC) on
A release message (REL) is transmitted to the EPBX (station C), and a release complete message (REL_COM) is transmitted from station C.
Upon receiving P), the release sequence ends.

The EPBX (station A) sends a disconnect message (D
When the ISC is received from the EPBX (station B), the caller's terminal 10 is blocked by a busy tone (BT) connection and a release message (REL) is sent to the EPBX (station B).
And a release sequence of a release completion message (REL_COMP).

FIG. 1 is a sequence example showing an embodiment in which the rerouting process is performed by the ISDN dedicated line 5 of FIG. 2, and FIG. 4 is a schematic flowchart of the rerouting process at that time. Hereinafter, the EPBX will be described using these figures.
From the terminal 10 accommodated in (station A), the EPBX (D
The process of connecting to the terminal 12 accommodated in the (station) will be described.

In FIG. 1, a dialing operation of a transmitting terminal 10 accommodated in an EPBX (station A) causes an EPBX to be operated.
(Station A) is an ISDN leased line 1 for EPBX (Station B)
A call setup (SETUP) message is sent out via the D channel of, and a call setup acceptance (CALL) is received from the EPBX (station B).
_PROC) message. Similarly, EPBX
(Station B) translates the connection destination number (called number) of the call setup (SETUP) message and performs a calling operation via the ISDN leased line 2.

However, as shown in FIG. 2, EPBX (C
Station), there is no detour or the detour route during all talks with respect to the partner route, so the EPBX (station B) is disconnected including the reason information of the ISDN layer 3 information element (for example, # 3: no partner route). (DISC) message.
Then, the EPBX (station B) transmits a release message (REL) to the EPBX (station C), and receives a release completion message (REL_COMP) from the station C. The sequence up to this point is the same as the sequence of the normal ISDN leased line shown in FIG.

On the other hand, when the EPBX (station B) receives the disconnection (DISC) message including the reason information of the ISDN layer 3 information element, it determines whether or not there is a detour route as shown in the flowchart of FIG. If there is a detour route and it is "empty", rerouting processing is performed. That is, after performing the call release processing between the EPBX (station B) and the EPBX (station C), the ISDN which is the detour route
A new calling sequence (SETUP,
CALL PROC) and EPBX (E and D stations)
, The called terminal 12 accommodated in the EPBX (station D) is called.

The call message (ALERT) from the EPBX (station D) includes the EPBX (station E) and the EPBX (B
(Station) to the EPBX (station A), and the ringing tone (RBT) is heard by the calling terminal 10. Then, when the receiving terminal 12 responds, the response message (CONN) and the response confirmation message (CONN) follow the same route. AC
K) is sent to EPBX (station A), and the connection process is completed.

The rerouting process is performed when the conditions shown in FIG. 4 are satisfied, and when these conditions are not satisfied, a normal cutting sequence is performed. The conditions are described below. (I) The reason value of the reason information element in the disconnection (DISC) message received from the partner route matches the data value set in advance (for example, # 3: no partner route). (Ii) There is a detour route and there is an empty channel.

As described above, according to the present embodiment, in a private network constructed with an ISDN leased line, it is possible to recognize a failure with respect to a partner route or all calls, and to find a valid bypass route to realize a bypass process.

Although the protocol sequence of the ISDN leased line is standardized, the present embodiment conforms to the standard in terms of sequence, and there is a problem even if there is an EPBX which does not correspond to this embodiment in the private network. It does not become.

[0023]

As described above in detail, according to the present invention, in a private network constructed with an ISDN leased line, ISDN layer 3 information is used.
Performing the rerouting (rerouting) process during the disconnection sequence has the effect of effectively rerouting what has been a call loss up to now and minimizing the call loss rate. Further, since no special device is required, the service can be performed at very low cost.

[Brief description of the drawings]

FIG. 1 is a rerouting sequence showing an embodiment of a rerouting scheme in a private network using an ISDN leased line according to the present invention.

FIG. 2 is a diagram illustrating a relay system showing an embodiment of a private network according to the present invention.

FIG. 3 shows a normal call processing sequence in the relay system shown in FIG. 2;

FIG. 4 is a flowchart showing an outline of a rerouting process in the embodiment.

FIG. 5 is a diagram showing a relay method of a private network in the related art.

[Explanation of symbols]

 10,12 subscriber terminal 1-5 ISDN leased line

Claims (1)

(57) [Claims] 1. An ISDN for performing connection processing from a first extension terminal accommodated in a first digital private branch exchange to a second extension terminal accommodated in a second digital private exchange via a relay station. In a rerouting method in a private network using a dedicated line, a call is set up between digital private branch exchanges via a D channel of an ISDN line, and reason information of an ISDN layer 3 information element is sent from the digital private branch exchange that has made the call setup. Upon receiving the disconnection message including the disconnection message, the digital private branch exchange that has received the disconnection message determines whether there is a detour route, and if there is a detour route, releases the call with the digital exchange that transmitted the disconnection message. Process, and a new call process on the detour route. Rerouting method in the private network used.