Multiplex communications – Communication techniques for information carried in plural... – Combining or distributing information via time channels
Reexamination Certificate
1998-11-03
2003-09-23
Ton, Dang (Department: 2732)
Multiplex communications
Communication techniques for information carried in plural...
Combining or distributing information via time channels
C370S522000
Reexamination Certificate
active
06625178
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a virtual private line control system, and more particularly to the technique for connecting and disconnecting a virtual private line using an ISDN network between private branch exchangers which have ISDN interfaces.
2. Description of the Related Art
Generally, the traffic of a telephone network changes depending upon the time zone and the day of the week. For example, in case of a telephone network system of an enterprise, the heaviest traffic tends to be during the beginning of the workday, immediately after noon, and immediately before the end of the workday. Thus, the heaviest traffic only occurs during several hours in a day.
A telephone network of an enterprise connects between the head office and each of offices, between the offices, between the head office and each of business stations, and between the business stations by private lines. Considering the high traffic hours, the enterprise contracts many telephone lines with a communication company. Therefore, some of the telephone lines are not used other than the high traffic hours. As a result, the line use efficiency decreases and the enterprise has to pay a telephone line use fee.
In order to eliminate the excessive number of private telephone lines and the excessive telephone line use fee, a virtual private line system which uses an ISDN network is proposed in Japanese Laid Open Patent Application (JP-A-Heisei 4-165892). In this reference, the number of private lines is made minimum, and virtual private lines using the ISDN network are set only for a high traffic time zone so as to increase the number of lines.
The virtual private line system adopts a time link system. In the time link system, virtual private line information is previously registered in a storage unit on the side of a station. The virtual private line information is composed of a time bit map in which the number of virtual private lines to be set with respect to route information, the number of channels, a call arrival number, a call origination number and a time zone are registered for every day and for every route. The station on the call originating side periodically searches the storage unit to read the registered virtual private line information for a present day. Then, the station refers to the time bit map to perform the setting or cancellation of the virtual private lines for a present time zone.
As described above, the conventional virtual private line system which uses the ISDN network adopts the time link system. An expected traffic is considered, and the number of virtual private lines, a connection start time of each of the virtual private lines, and a time interval are previously set in a station data. The connection of the virtual private line is realized in accordance with the station data. For this reason, even if there is not generation of any event such as a call origination at all when the virtual private line information is periodically referred to, the connecting process of the virtual private lines is performed for the number of virtual private lines set in the time zone of the time bit map. Therefore, the conventional virtual private line system is effective when the actual traffic at that time is equal to or near to the expected traffic. However, if the actual traffic at that time is lower than the expected traffic, excessive virtual private lines are connected. As a result, the improvement of the decrease of the line use efficiency and the improvement of payment of the telephone line use fee are not always enough.
Also, when events more than the expected traffic are generated, the lack of the virtual private lines occurs to cause a communication loss.
In addition the above reference, a variable communication network is described in Japanese Laid Open Patent Application (JP-A-Showa 59-127458). In this reference, a first exchanger and a second exchanger are directly connected by a first line. The first and second exchangers are connected by a second line group via one or more other exchangers. The first exchanger and each of the exchangers of a network includes a line selecting circuit for selecting an optional one of the second line group as a virtual fixed connection line. A flag field for indicating the second line group is captured for the virtual fixed connection line is provided in a signal format of a signal system between the first exchanger and each exchanger of the network. When the second line group is captured, it is set in the flag field. Thus, an optional line is captured as the virtual fixed connection line and the number of virtual fixed connection lines is adjusted based on the traffic on the first line.
A virtual private line connecting system is described in Japanese Laid Open Patent Application (JP-A-Heisei 3-125551). In this reference, private branch exchangers are connected via an ISDN network. A D channel signal circuit and a PBX—PBX common line signal circuit are connected to a D channel and a plurality of B channels on a user and network interface. Links by a plurality of B channels or HO channels are formed in the ISDN network by the D channel signal circuit. One of the plurality of B channels is connected to the PBX—PBX common line signal circuit for a virtual private line.
In addition, a virtual private line connecting system is described in Japanese Laid Open Patent Application (JP-A-Heisei 5-244250). In this reference, a call is originated from a terminal
1
to a terminal
16
. When a private trunk
1
line
3
is in a communication state, an empty channel is selected and a call origination event is notified to a central control unit
8
for establishment of a virtual private lie. The central control unit
8
originates a call to an ISDN network
17
using one of numbers registered in a main storage unit
18
. In a call arriving station, a central control unit
14
performs a call arriving process to a compressed speech trunk
12
which automatically responds to the ISDN network
17
via a first interface group circuit
10
. The central control unit
8
connects a communication path switch of a compressed speech trunk
6
via a first interface group circuit
4
. As a result, a virtual private line is established through the ISDN network
17
.
Also, a communication control apparatus is described in Japanese Laid Open Patent Application (JP-A-Heisei 6-181474). In this reference, when determining that a data transmission amount of an information processing apparatus par a unit time which is detected by a traffic detecting section
23
exceeds an upper limit of allowable range of data transmission amount at present, a traffic determining section
25
notifies to a packet exchange control section
24
, an instruction for adding one virtual line to the same recipient. The packet exchange control section
24
sets another new virtual line between the information processing apparatus and the above recipient on an INS-P. Thereafter, the information processing apparatus performs a packet communication using the two virtual lines.
SUMMARY OF THE INVENTION
The present invention is accomplished in view of the above problems. Therefore, an object of the present invention is to provide a virtual private line control system and a method for the same, in which the connection and disconnection of a virtual private line using an ISDN network are performed in response to generation of an event such as a call origination, in a private branch exchanger which has an ISDN interface.
In order to achieve an aspect of the present invention, a private branch exchanger which is connected to an ISDN network, includes an identifying unit for identifying a specific one of a plurality of virtual private lines in response to an event, for determining whether the specific virtual private line is usable, and for issuing a communication instruction when the specific virtual private line is usable. A communication unit performs communication using a specific channel corresponding to the specific virtual private line in response to the communica
Hokari Makoto
Okumura Takashi
Dickstein Shapiro Morin & Oshinsky LLP.
Ton Dang
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