Virtual private line control system with improved transmission efficiency

• US 6,625,178 B1
• Filed: 11/03/1998
• Issued: 09/23/2003
• Est. Priority Date: 11/12/1997
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Hokari, Makoto, Okumura, Takashi
• Primary Examiner(s): TON, DANG T
• Application Number:
  US09/185,459
• Time in Patent Office: 1,785 Days
• Field of Search: 370/229, 370/230, 370/252, 370/396, 370/397, 370/398, 370/399, 370/395.2, 370/395.21, 370/395.61, 370/409, 370/419, 370/420, 370/522, 370/904, 370/524, 370/465, 370/468, 370/351, 370/352, 370/389, 370/401, 379/224, 379/225, 379/231, 379/232, 379/233, 379/234
• US Class Current: 370/524
• CPC Class Codes: H04Q 11/0428 Integrated services digital network, i.e. systems for transmission of different types of digitised signals, e.g. speech, data, telecentral, television signals
• CPC Class Codes: H04Q 2213/13209 ISDN
• CPC Class Codes: H04Q 2213/1322 PBX
• CPC Class Codes: H04Q 2213/13384 Inter-PBX traffic, PBX networks, e.g. corporate networks
• CPC Class Codes: H04Q 2213/13399 Virtual channel/circuits
• CPC Class Codes: H04Q 3/62 for connecting to private branch exchanges

Abstract

In a private branch exchanger which is connected to an ISDN network, a virtual private line information table stores information indicating channels corresponding to virtual private lines in units of routes. An identifying unit determines a route in response to an event, refers to the virtual private line information table based on the determined route to determine a specific one of the channels corresponding to the virtual private lines for the determined route. Also, the identifying unit determines whether a connection of a specific virtual private line corresponding to the specific channel to an ISDN network is established. When the specific channel corresponding to a specific virtual private line is usable, the identifying unit issues a communication instruction. A communication unit performs communication using the specific channel corresponding to the specific virtual private line in response to the communication instruction.

Claims

1. A private branch exchanger which is connected to an ISDN network, comprising:

a virtual private line information table, said table storing information indicating channels corresponding to virtual private lines in units of routes and stores connection state information indicating whether each of said plurality of virtual private lines is in a connected state or in a disconnected state, and communication state information indicating whether a channel corresponding to each of said plurality of virtual private lines is in an empty state or a communication state;

an identifying unit for determining a route in response to an event, said identifying unit referring to said virtual private line information table to determine a specific one of said channels corresponding to said virtual private lines for the determined route, for determining whether a connection of a specific virtual private line corresponding to said specific channel to said ISDN network is established, and for issuing a communication instruction when said specific channel is usable; and

a communication unit, said communication unit performing communication using said specific channel in response to said communication instruction;

wherein said identifying unit refers to said virtual private line connection information table to determine whether the connection sate information of each of said virtual private lines for the determined route is in said connected state or in said disconnected state, issues said communication instruction when at least one of said channels of said virtual private lines for the determined route as said specific channel has the communication state information of said empty state, and changes the communication state information for said specific channel from said empty state to said communication state.

2. A private branch exchanger according to claim 1, wherein said identifying unit issues a connection instruction, when all of said channels corresponding to some of said virtual private lines for the determined route have the communication state information of the communication state while ones of said virtual private lines for the determined route other than said some virtual private lines have the connection state information of said disconnected state, and

wherein said private branch exchanger further comprises a connection control unit for establishing the connection of one of said virtual private lines for the determined route as said specific virtual private line which has the connection state information of said disconnected state, in response to said connection instruction, and for changing the connection state information for said specific virtual private line to said connected state, and the communication state information for said specific channel corresponding to said specific virtual private line to said communication state.

3. A private branch exchanger according to claim 2, further comprising a monitoring unit for monitoring said channels of said virtual private lines, for changing the communication state information of said specific channel to said empty state when the communication is ended.

4. A private branch exchanger according to claim 3, wherein said virtual private line connection information table further includes a line capture time setting information indicating a time for which each of said virtual private lines should be captured after the communication is ended, and a remaining capture time information indicating a time for which said ach virtual private line should be remained in a captured state, and

wherein said monitoring unit sets the line capture time setting information to the remaining capture time information when the communication is ended.

5. A private branch exchanger according to claim 4, wherein said monitoring unit monitors said channels of said virtual private lines for every predetermined time, and updates the remaining capture time information for every channel based on the monitoring result.

6. A private branch exchanger according to claim 5, wherein said monitoring unit issues a disconnection instruction when one of said virtual private lines has the remaining capture time information of 0, and

wherein said connection control unit disconnects said one virtual private line having the remaining capture time information of 0.

7. A private branch exchanger which is connected to an ISDN network, comprising:

a virtual private line information table which stores information indicating channels corresponding to virtual private lines in units of routes;

an identifying unit for determining a route in response to an event, for referring to said virtual private line information table based on the determined route to determine a specific one of said channels corresponding to said virtual private lines for the determined route, for determining whether a connection of a specific virtual private line corresponding to said specific channel to an ISDN network is established, and for issuing a communication instruction when said specific channel corresponding to said specific virtual private line is usable; and

a communication unit for performing communication using said specific channel corresponding to said specific virtual private line in response to said communication instruction.

8. A method according to claim 7, further comprising the steps of:

issuing a connection instruction, when all of said channels corresponding to some of said virtual private lines for the determined route have the communication state information of the communication state while ones of said virtual private lines for the determined route other than said some virtual private lines have the connection state information of said disconnected state;

establishing the connection of one of said virtual private lines for the determined route as said specific virtual private line which has the connection state information of said disconnected state, in response to said connection instruction; and

changing the connection state information to said connected state.

9. A method according to claim 8, further comprising the steps of:

monitoring said channels of said virtual private lines; and

changing the communication state information of said specific channel to said empty state when the communication is ended.

10. A method according to claim 9, wherein said virtual private line connection information table further includes a line capture time setting information indicating a time for which each of said virtual private lines should be captured after the communication is ended, and a remaining capture time information indicating a time for which said each virtual private line should be remained in a captured state, and

wherein said monitoring step includes setting the line capture time setting information to the remaining capture time information when the communication is ended.

11. A method according to claim 10, wherein said monitoring step includes:

monitoring said channels of said virtual private lines for every predetermined time; and

updating the remaining capture time information for every channel based on the monitoring result.

12. A method according to claim 11, further comprising the steps of:

issuing a disconnection instruction when one of said virtual private lines has the remaining capture time information of 0; and

disconnecting said one virtual private line having the remaining capture time information of 0.