KR100333995B1 - Method and device for recovering ISDNBRI links without losing calls - Google Patents

Abstract

It is determined by the telecommunication switching systems in response to the initialization of the new BRI interface whether a communication terminal connected to the new BRI interface is currently active on another BRI interface in the telecommunication switching system. If the answer is yes, then the telecommunication switching systems automatically forward all active calls from the other BRI interface to the new BRI interface while preventing the loss of active calls.

Description

Method and device for recovering ISDN BRI links without losing calls

Technical field

The present invention relates to telecommunication switching systems having telecommunication terminals interconnected to telecommunication switching systems via ISDN basic speed interfaces (BRI) in telecommunication switching systems, in particular the loss of active calls to telecommunication terminals. It is about the ability to interchange the BRI interfaces of the communication terminal without.

Background of the Invention

In conventional telecommunication switching systems, communication terminals are interconnected to telecommunication switching systems via BRI links connected to BRI interfaces in telecommunication switching systems. In normal operation of installed telecommunication switching systems it is sometimes necessary to exchange the BRI interfaces to which telecommunication terminals are connected. In conventional systems for such an exchange, the technician has to wait until the BRI communication terminal is idle, resulting in a large amount of time wasted. In addition, complex procedures must be programmed into the telecommunications switching node so that the BRI communication terminal is used in the idle state, and only then should the telecommunications switching systems inform the technician that the BRI communication terminal is now busy-out. The technician can then proceed to connect the BRI link of the communication terminal to another BRI interface in the telecommunication switching systems. Prior art telecommunication switching systems, which have contributed greatly as disclosed in US Pat. No. 5,386,466, have many individual switch nodes, each of which handles a relatively small number of BRI links. Because of this property of telecommunication switching systems with respect to the latter patent, the number of rearrangements of BRI interfaces is increased.

In the prior art, there is clearly a need for a procedure that allows a BRI link connection to another BRI interface without losing an active call on a communication terminal attached to the BRI link.

The following problem is solved, and an apparatus relating to telecommunication switching systems corresponding to the initiation of a new BRI interface to determine if a communication terminal connected to the new BRI interface is currently active on another BRI interface in the telecommunication switching system. Technological advances are made by the method, if the answer is yes, the telecommunications switching systems automatically send all active calls from the other BRI interface to the new BRI interface preventing the loss of active calls.

Other or additional aspects of the present invention will become apparent by reference to the accompanying drawings during the course of the following description.

1 is a block diagram illustrating a telecommunication switching system embodying the concepts of the present invention.

2 illustrates a software structure in accordance with the present invention.

3 is a block diagram illustrating in more detail the switch node of the telecommunication switching system of FIG.

4 and 5 illustrate terminal records.

6 is a flowchart showing steps executed by an application program.

* Description of the symbols for the main parts of the drawings *

101, 102, 103: switch node

104,106,113, 114, 116, 117: communication terminal

123, 126, 129, 130, interface

127: network

128: node processor

details

1 shows telecommunication switching systems having multiple switch nodes 101, 102, 103. Advantageously, the switch nodes of FIG. 1 function as an integrated system to provide telecommunications services as provided by individual or network AT & T Definity Generic 2 communication systems. As shown in FIG. 1, telecommunications switching systems include communication terminals 104, 106 interconnected to switch nodes 101-103 via BRI links 109, 112 and 118-202. (113-117). The switch node then connects between the communication terminals using internal switching networks and interconnection to other switch nodes via PRI links 107, 108, 110. The communication terminals can be BRI station sets or other BRI communication terminals, such as facsimile devices, computers, or data modems. Each BRI link is connected to a switch node through an internal interface within the switch node. For example, BRI links 109 and 112 are connected to switch node 102 via interfaces 126 and 123, respectively. A detailed description of the switch node 102 is made in FIG. 3. The switch node 102 is controlled by the node processor 128. Various voice and signal paths are established through the network 127 under the control of the node processor 128. The node processor 128 also controls the interfaces 123, 124, 126, 127, 129, 130. Interfaces 129 and 130 interface PRI links 107 and 110 to switch node 102, respectively.

In order to better understand the concept of the present invention, consider the following examples. The communication terminal 104 is connected to the BRI link 118, the switch node 101, and the PRI when the technician unplugs the BRI link 112 from the interface 123 to reconnect the BRI link 112 to the interface 124. It is used to make active calls or signal processing to the communication terminal 113 via the link 107, the interface 129, and the network 127. If the reconnection is made within 90 seconds to avoid the usual timeout defined by the ISDN protocol, the active call used by the communication terminal 104 is not terminated. If the communication terminal 104 is a BRI station set, the user of the station set will have an interrupted conversation for the time period it takes for the technician to reconnect the BRI link 112 to the interface 124. If the communication terminal 104 is a facsimile device or data modem, then an error will occur but the information will be retransmitted to recover the error condition. Thus, regardless of whether the communication terminal is used for an active call, the descriptor may Can be rearranged.

As described above with respect to FIG. 3, when the BRI link 112 is connected to the interface 124, the interface 124 undergoes the initial processing described in more detail in US Pat. No. 5,386,466, which is incorporated herein by reference. To start. Node processor 128 over network 127 requests a service profile ID (SPID) from communication terminal 104 in response to initialization of interface 124. The SPID uniquely identifies the communication terminal 104. Node processor 128 then checks the internal table to determine if communication terminal 104 is currently assigned to another interface. In this embodiment, node processor 128 determines whether communication terminal 104 is assigned to interface 123 and is active at the time of invocation. The node processor 128 responds to this information to reconnect the call from the interface 129 to the interface 124 instead of the interface 123 via the network 127.

2 shows a software structure of the switch nodes of FIG. The structure is based on a conventional OSI model that has been modified to implement the ISDN protocol. Further changes have been made to incorporate the present invention into this model. Software layers 205-209 are described in US Pat. No. 5,386,466.

The main function of the physical layer 201 is to terminate the physical links. In particular, the physical layer 201 is responsible for the management of physical channels and the control of physical subchannels above them. Physical layer 201 includes a software portion and physical interfaces. In addition, the software portion of the physical layer 201 directly controls the physical interface through which the physical links communicate with the PRI and the BRI information is terminated. Physical layer 201 provides physical subchannels and physical channel to link layer 212 as entities that can be controlled by link layer 212.

The main function of the link layer 212 is to ensure that the information transmitted over the physical channel is intact and recovered in the correct order. This is done using another layer of protocol (called physical packet protocol) that allows multiple communication paths (generally called logical links) to be established on a given physical channel or physical subchannel carrying packetized data. These logical links are used to identify and process data passed between link layer 212 and physical layer 201. In ISDN Q.921, the protocol used is the LAPD packet protocol. Link layer 212 also allows higher software layers to control physical layer 201 in an abstract manner. Link layer 212 uses a first layer of software protocol.

As shown in FIG. 2, the link layer 212 is divided into a link interface 202 and a link management 203, where the reason for this division is described below. In this case, it may be helpful to consider the communication of ISDN signals through the D channel in order to assist the readers with basic knowledge of the communication of ISDN signals through the D channel. In the link layer 212, a plurality of logical links are established on the D channel. Only one of these logical links carries ISDN control signals, which is called a logical D channel (LDC). The LDC is identified by a logical D channel number (LCDN).

Link interface 202 performs many of the functions performed by link layer 212, including the establishment of logical links. Link management 203 identifies various link interfaces for higher software layers. Link management 203 also communicates information between logical links and higher software layers.

The network layer 204 processes the information carried on the LDC and terminates the ISDN Q.931 protocol. Thus, this layer is responsible for determining whether system resources are available for call termination or initiation outside the switching node. The network layer controls the allocation of channels on the interface on which the call is received or established. Further details of how the network software layer 204 functions with respect to the establishment of calls are described in US Pat. No. 5,386,466.

3 illustrates in block diagram form the software structure of FIG. 2 implemented at switch node 102. The software layers 203-209 are implemented on the main processor of the switch node 102, which is the node processor 128. In particular, the software layers through the link management portion of the link layer are realized by the software layers indicated by 316 through 310 in the node processor 128. The link interface portion of the link layer is implemented by a software module node of the node processor 128 represented by a local angel 302.

The physical layer is jointly implemented by hardware and software. In particular, the hardware portion of the physical layer of the switch node 102 is implemented by interfaces 123, 124, 126, 129, and 130. The software portion of the physical balance is performed by the local angel 302. Interfaces 129 and 130 are not shown in FIG. 3.

In FIG. 3, communication terminal 104 may preferably be an AT & T ISDN 7506 station set or a wireless base station. In addition, one skilled in the art can readily appreciate that terminal manager 318 may be another type of software application. Returning to the previous embodiment, once the BRI link 112 is disconnected from the interface 123 and reconnected to the interface 124, the interface 124 associated with the elements 302-311 initiates low level initialization, This is described in US Pat. No. 5,386,466. After the low level initialization is complete, a new logical connection is established between communication terminal 104 and terminal manager 318. This new logical connection is identified by the new LDCN number. Terminal manager 318 requests a service profile ID (SPID). After receiving the SPID from the communication terminal 104, the terminal manager 318 then scans the terminal record table shown in FIG. 4 to match the SPID received from the communication terminal 104, such as an SPID 401. Find the SPID entry. 4 shows the state of terminal records before BRI link 112 is disconnected from interface 123. If the SPID 401 is the same as the SPID received from the communication terminal 104 and the call record 403 indicates an active call, then the terminal manager 318 no longer connects the BRI link 112 to the interface 123. The terminal record 400 is updated to indicate that it is not. LDCN 404 is associated with a connection through interface 123. The call record 403 also includes information identifying the interface 123. The new LDCN number associated with the connection through interface 124 is LDCN 502. Terminal manager 318 updates terminal record 400 to indicate that LDCN number is now LDCN 502. Call record 501 also indicates that the call is now via interface 124. After updating the terminal record 400, the terminal manager 318 may cause the lower software layers 302-313 to establish a connection from the interface 124 to the interface 129 using the LDCN 501 of the terminal record 400. To ask.

If there is no entry in the call record 403 indicating an active call, no connection will be made through the network 127. However, terminal record 400 is still updated to indicate the interface to which communication terminal 104 is connected, which is shown in FIG. The manner in which the software layers 302-313 handle calls to the LDCN is described in US Patent Application No. O8 / 451282, "Adjustment of Call Band During Communication Call," filed May 26, 1995, and the present application. It is likewise assigned to the same assignee and US Pat. No. 08/451282 is incorporated herein by reference.

6 illustrates operations performed by terminal manager 318. Decision block 601 determines whether the BRI link is initialized. If the answer is no, block 602 performs normal processing. If the answer is yes at decision block 601, block 603 requests a SPID from a terminal connected on the initializing BRI link. Decision block 604 determines whether the SPID has been received. If the answer is no, block 606 performs error recovery. Note that after blocks 602 and 606 execute the processing, these blocks return control to decision block 601.

If the SPID was received from the terminal, decision block 607 examines the call record associated with the terminal record to determine if the terminal is active for the call. If the answer is no, block 608 updates the terminal record to indicate that the terminal is currently connected to the system via an initializing BRI link before returning control to decision block 601. If the answer at decision block 607 is yes, block 609 updates the terminal record to include the new LDCN number by replacing the existing LDCN number associated with the interface to which the initial BRI link is already connected. In addition, block 609 updates the call record of terminal record 400, which is illustrated by call record 501. In addition, in FIG. 5, the new LDCN is represented by the LDCN 502 of the terminal record 400. FIG. After executing block 609, block 611 requests that the network layer connect the initializing BRI link to the second half of the active call reflected in the call record 501. In the present embodiment, the second half of the call is terminated on interface 129. After executing block 611, control is passed back to decision block 601.

The present invention relates to telecommunications switching systems having telecommunication terminals interconnected to telecommunications switching systems by ISDN basic speed interfaces (BRI) in telecommunications switching systems, the communication without loss of an active call at the telecommunications terminal. Interchange the terminal's BRI interfaces.

Claims (10)

A method of rearranging communication links connecting said communication terminals to a telecommunication switching system while maintaining active telecommunication calls to said communication terminals, the method comprising: Detecting initialization of a communication terminal on a first telecommunication interface of the telecommunication switching system; Requesting terminal identification information from the communication terminal; Receiving the terminal identification information from the communication terminal; Comparing the received terminal identification information with stored information to determine if the communication terminal is in an active telecommunication call state on a second telecommunication interface of the telecommunication switching system; A telecommunications call connection step of connecting the telecommunications call to the first telecommunications interface when the telecommunications terminal is in an active telecommunications call state such that the active telecommunications call is maintained at the telecommunications terminal. Rearrange method. The method of claim 1, wherein the comparing step comprises: maintaining a record for each of the active communication terminals; And storing in each record call information identifying the active call. 3. The method of claim 2, wherein the connecting step includes accessing a record for the communication terminal to obtain an identification of the active call. The method of claim 1, wherein the communication terminal is a telephone station set. The method of claim 1, And the communication terminal is a wireless base station. 11. An apparatus for rearranging communication links connecting said communication terminals to a telecommunication switching system while maintaining active telecommunication calls to said communication terminals. Means for detecting initialization of a communication terminal on a first telecommunication interface of the telecommunication switching system; Means for requesting terminal identification information from the communication terminal; Means for receiving the terminal identification information from the communication terminal; Means for comparing the received terminal identification information with stored information to determine if the communication terminal is in an active telecommunication call state on a second telecommunication interface of the telecommunication switching system; Telecommunication call connection means for connecting the telecommunication call to the first telecommunication interface when the telecommunication terminal is in an active telecommunication call state such that the active telecommunication call is maintained at the telecommunication terminal. Link rearrangement device. 7. The apparatus of claim 6, wherein the comparing means comprises: means for maintaining a record for each of the active communication terminals; And means for storing in each record call information identifying said active call. 8. The apparatus of claim 7, wherein the connecting means comprises means for accessing the record for the communication terminal to obtain an identification of the active call. 7. The apparatus of claim 6, wherein the communication terminal is a telephone station set. 7. The apparatus of claim 6, wherein the communication terminal is a wireless base station.

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