WO2000011829A2

WO2000011829A2 - Error cancellation in the switching device of a communication system

Info

Publication number: WO2000011829A2
Application number: PCT/DE1999/002578
Authority: WO
Inventors: Johannes Wollenweber; Rudolf Stelz
Original assignee: Siemens Aktiengesellschaft
Priority date: 1998-08-17
Filing date: 1999-08-17
Publication date: 2000-03-02
Also published as: EP1106032A2; CN1314066A; DE19837216A1; WO2000011829A3; CA2340710A1; DE19837216C2

Abstract

According to this invention and after the occurrence of an error, the link data redundantly saved elsewhere are used for maintaining the communication link. The present invention also relates to a switching device (EXC) having a central unit (MP) that comprises a data memory for storing the communication-link data which is signaled and switched by the allocated peripheral structural components (LIC1, LIC2)._______________________________________________________________________________________________________________________________________________________________________________

Description

description

Troubleshooting in a switching center of a communication system

The invention relates to a method for repairing an Def ^¬ coupler in an active peripheral assembly of a switching ^¬ device in a communication system, especially in an ATM (Asynchronous Transfer Mode) communication system, wherein a si ^¬ gnalisierte communication link is mediated by the active peripheral module at least, and where ^¬ when connection data of the communication connection are stored in the active peripheral module in order to handle the communication connection. The invention relates to WEI terhin a switching device for a Kommunikationssy ^¬ stem, particularly for an ATM communication system having a central control unit for controlling a plurality of associated peripheral modules are placeable over the communication links.

It is known to mediate communication connections via switching modules of a switching device in switching devices of communication systems, that is to say to handle, in particular to set up, maintain and terminate the communication connections with the aid of hardware components of the peripheral modules. It is also known to control a plurality of peripheral modules via a central internal computer. The central computer in particular transmits signals for establishing and breaking down communication connections to the peripheral modules.

It is known from ATM communication technology to establish and maintain permanent and signaled communication connections. The permanent communication connections are usually set up by the operator of a communication system and opened over long periods of time. keep right. The reliability in terms provided ^¬ stakes particularly high Anforde of permanent communication links.

_S ignalisierte communication connections are made at the request of the operator or a user of the communications system and away maintained as the permanent communication links usually have shorter periods. A signaled communication connection is terminated, for example, by hanging up a telephone handset. It is typical of a signaled communication connection that it is left to the communication system over which chain of several possible physical sections for the transmission of communication signals the communication signal is established.

It is also known to establish and maintain signaled permanent communication links that are maintained over a similar period of time as permanent communication links. The signaled permanent communication connections have similarly high reliability requirements as the permanent communication connections. In contrast to the permanent communication connections, the operator or a user of the communication system specifies only a part of the nodes of the communication system and / or only a part of the physical transmission sections via which the communication connection is to be established when establishing a signaled permanent communication connection. Otherwise, the establishment of a signaled permanent communication connection is left to the communication system. As with signaled communication connections, additional connection data and / or connection data of a different type are stored in signaled permanent communication connections compared to permanent communication connections in order to handle the communication connections. In order to be able to correct errors in an active peripheral module, it is known to provide redundant peripheral modules and / or redundant transmission links. If one peripheral module or transmission link fails, the communication connection or the communication connections are relocated to the redundant peripheral module and / or transmission link. A distinction is made between different types of redundancy. For example, I / O modules can have 1 + 1 redundancy or 1: N redundancy.

With 1 + 1 redundancy, a passive I / O module is provided for a single active I / O module, which is only available as a stand-by module for the active I / O module. As a result, essentially the same hardware and software settings can be present in the passive, redundant assembly as in the active assembly. In practice, however, the software settings change, in particular the connection data stored in the module, in short intervals. The software of the passive, redundant module is therefore not reliably up to date, so that it is not possible to switch from the active to the passive module without updating the software or the connection data. Furthermore, there is no guarantee that the same hardware settings will be present in both modules at all times. For this reason, a loss of all signaled communication connections must be expected, even if it is possible that some of these signaled communication connections can be maintained. In addition, when switching from an active transmission link to a 1 + 1 redundant transmission link, it is possible that several 1 + 1 redundant peripheral modules have to be switched over. This increases the likelihood that a large part or all of the signaled communication connections are lost.

In the case of 1: N redundancy, there is only one common redundant module for a number N> 1 of modules. Presettings in the redundant module, which accelerate a switchover from one of the N active modules to the redundant module, or ensure the maintenance of existing signaled communication connections, can therefore not be made or can only be carried out to a limited extent using the known method.

If software errors occur in an active peripheral module, it is known to reset and restart the entire module. All connection data of signaled communication connections are deleted, so that all these communication connections are terminated.

The present invention is based on the object of specifying a method for eliminating a fault in an active peripheral module of the type mentioned at the outset, in which stable signaled communication connections can be reliably maintained after the fault has occurred. Another object of the invention is to provide a corresponding switching device.

The problems are solved by a method with the features of claim 1 or by a device with the features of claim 10. Further training is the subject of the dependent claims.

On the method side, the connection data of the at least one communication connection, which are stored in the active peripheral module, are also stored redundantly elsewhere. After the error has occurred, the connection data stored elsewhere is used to further handle the communication connection. By the Saving two current sets of connection data ensures that the connection data is at least present again in the active peripheral module even after the failure or after the occurrence of the error. If the redundant set of connection data, or at least one of the redundant sets of connection data, is undamaged after the occurrence of the error, the undamaged data set can be used to further handle the communication connection. This makes it possible to maintain the at least one signaled communication link if it is still stable after the error has occurred. In order to exclude the possibility that the set of connection data stored in the faulty peripheral module is damaged and thus jeopardizes the maintenance of the at least one communication connection when it is used further, the connection data stored in the faulty peripheral module is preferably deleted.

The method according to the invention has the advantage that signaled communication connections can be maintained with the same reliability as permanent communication connections, which, like the signaled communication connections, can be m-stable after the occurrence of the error or can no longer be maintained due to the error.

A peripheral assembly is understood to mean an assembly or structural unit of a switching device that is directly involved in the establishment and / or maintenance of a communication connection. Peripheral modules are understood in particular to mean: interface modules (Line Interface Cards LIC) which form an interface to transmission lines external to the switch, multiplexer units (for example Satistical Multiplexmg Units SMU) which connect a plurality of interface modules to a switching matrix, coupling fields (ATM Switchmg Networks ASN), which send incoming signals to the correct one of several possible outputs. The modules have in particular a large number of elements which perform functions of the module, but at least a memory area for storing the connection data and an element which is directly involved in the communication connection. The invention can also be used in other communication systems, for example in STM (Synchronous Transfer Mode) communication systems.

A switching device in a communication system is understood to mean a device by means of which different external and / or internal transmission links or transmission lines can be connected to one another or activated for establishing a communication connection.

A communication connection is understood to mean a connection of any type via which signals can be transmitted within the communication system or across the limits of the communication system.

Before the error occurs, the connection data are preferably stored in a memory device which is central for a plurality of the peripheral modules. In particular, the storage device is part of a central switching computer of the switching device. In this case, the switching computer can, for example, update the copy of the connection data stored in its storage device whenever it informs the active peripheral module of changes which affect the connection data.

But otherwise the central storage of the connection data has the same for a majority of the peripheral modules

Advantage that a common storage unit or Storage device is sufficient and that the data management can be implemented in an effective manner.

In a further development, a redundant passive peripheral module is available for the active peripheral module, in which the connection data are stored redundantly. In contrast to the prior art, a set of the connection data is stored in the passive peripheral module, which is just as current as the set of connection data in the active peripheral module. On the one hand, this gives you the option of simply switching to the passive I / O module after the error occurs in the active I / O module, and on the other hand you have the option of transferring the connection data from the passive peripheral module to the active I / O module, for example, if it is in the active I / O module stored connection data are incorrect or there is a possibility that they are incorrect.

If an error occurs in the software of the active peripheral module, after the error has occurred, the connection data, which is stored redundantly elsewhere, is preferably transmitted to the still active peripheral module. Errors in the software mean both errors in programs and errors in stored data which can be accessed during a program run.

In many fault situations, continuing to operate the active peripheral module is the fastest and most reliable way to maintain stable communication links without significant interruptions. In most cases, hardware settings for the active peripheral module for maintaining a communication connection are still available even after the error has occurred. This is preferably done after the transmission of the connection data stored redundantly elsewhere or at least after _d he transfer of part of this connection data on ^¬ pr _ü ft. When checking can for example also Festge ^¬ provides are that the elsewhere redundant gespeicher ^¬ th connection data have changed in the meantime because they were updated, so that appropriate corrections or changes to the Hardware settings are required. A possible reason for this is the message that has meanwhile been received by a central switching computer that a communication connection is to be ended.

An embodiment of the method is preferred in which the connection data to be transmitted remain stored at the other location, that is to say are transmitted as a copy. This also applies in particular to the case that after the error has occurred, the previously active peripheral module becomes passive and a redundant module is used as the active peripheral module, into which the connection data stored elsewhere is transmitted. This process variant represents a possibility, particularly in the case of hardware errors in the previously active peripheral module, of keeping the stable communication connections.

A development of the method is particularly preferred in which the transmission of the connection data is interrupted or the peripheral module active after the error occurs or is only started at a later point in time in order to enable the establishment of new communication connections. The connection data to be transmitted are expediently transmitted in blocks to the active peripheral module. A major advantage of this development is that as soon as it is certain which peripheral module will take over or continue active operation after the error has occurred, new communication connections can be set up, the same method as in error-free operation being able to be carried out. On the device side, the above-mentioned object of the invention is achieved in that the central control unit of the switching device has a data memory in which connection data from signaled communication connections which are transmitted via the assigned peripheral modules can be stored, and in that a transmission unit for reading out and transmitting the connection data to the associated peripheral modules is provided. Advantages and further developments result from the above description of the method according to the invention and its further developments.

Exemplary embodiments of the invention will now be described with reference to the accompanying drawing. However, the invention is not limited to these exemplary embodiments. The only figure of the drawing designated as FIG. 1 shows:

a switching device with two 1 + 1 redundant interface modules during troubleshooting.

The switching facility EXC of a communication system shown in FIG. 1 has two mutually 1 + 1 redundant interface modules LIC1, LIC2. A large number of communication connections are established, maintained and / or terminated via the respectively active interface modules LIC1, LIC2. For this purpose, connections are not shown

Interface modules LIC1, LIC2 connected to external sub-sections of transmission lines, also not shown, for the transmission of communication signals. Internally, the interface modules LIC1, LIC2 are connected to additional modules of the switching device EXC, which are still not shown. These modules, for example multiplexer modules, switching matrix modules and other interface modules, are the incoming and / or outgoing communication signals on defined sections at the active interface module LIC1, LIC2 transferable from communication lines. The fix described below is in entspre ^¬ chender way transit even with these and other types of peripheral modules of a switching device ^¬ bar. In a first exemplary embodiment for troubleshooting, a software error occurred in the LIC2 I / O module. In order to remedy the error, the interface module LIC2 is reset, whereby all data not stored in permanent memories are lost. This effect is desirable because it ensures that erroneous data is deleted. In comparison, the on ^¬ wall usually considerably large for accurate localization of faulty components of non total of erroneous data.

After resetting the interface module LIC2, basic data from a database manager DBMS of a central switching computer MP are first transferred or transferred to a database CDB of the interface module LIC2. In particular, data can be transmitted from programs that serve to perform the functions of the LIC2 peripheral module. As an alternative or in addition, a permanent memory, for example an FEPROM, is provided in the peripheral module LIC2, in which program data are stored and from which, after the data has been reset, a volatile memory, for example a RAM, is copied, which the database CDB has. It has already been proposed to transmit data from permanent communication connections to the interface module LIC2 in method step a, which data are stored redundantly in the central switching computer MP. It is also known, after performing method step a, to check the hardware settings of the connection hardware ASIC of the interface module LIC2 for consistency with the data of the permanent communication connections and to make any necessary corrections to the hardware settings. The connection manager COH of the interface module LIC2 is active, m- which he reads the data from the CDB database and takes the corresponding test steps.

B in process step will now be transferred to the central mediation computer MP redundantly stored connection data signaled communication links in the interface of ^¬ lenbaugruppe LIC2 that ^¬ using the connection hardware ASIC are ten of the interface module LIC2 upright sustainer ^¬ or were. It is possible that one or more of the signaled communication connections have been interrupted or broken off due to the error that has occurred. In method step b, a switching data manager RHS of the central switching computer MP transmits the connection data of the signaled communication connections to the connection manager COH of the interface module LIC2. The connection data are transmitted in data blocks of a specified length. The connection manager COH takes 5 ms to receive a data block, for example, connection data from about 30 signaled communication connections of the interface module LIC2 being received. After receiving the data block, the connection manager COH begins with a check of the hardware settings of the corresponding communication connections, which are carried out in the connection hardware ASIC (method step d). The connection manager COH takes, for example, about half a second to read the connection data and check their consistency with the hardware settings for about 30 communication connections.

Method step b 'is carried out in parallel with method step b). In method step b ', the connection manager COH is informed by the switching data manager RHS when a request to set up a new communication connection has been received by the central switching computer MP. Before the transmission of the first data block, method step b or between the transmission of two data The connection manager COH responds to the request by establishing a new communication connection in accordance with the connection data it receives from the connection data manager RHS together with the information about the existence of the request. The new communication link can be a signaled or a non-signaled communication link. If there are requirements to set up several new communication connections, the procedure is followed accordingly. The relevant data can be transmitted individually or in blocks to the COH connection manager. The requirements for new communication connections preferably have priority over the checking of the hardware settings of existing communication connections, so that they are processed primarily by the connection manager COH. Furthermore, however, a period of time with a predetermined length is preferably provided, after which the connection manager COH receives connection data from existing communication connections again at the latest or continues with checking the hardware settings of communication connections whose connection data are already available to him. For example, in practice, when operating communication systems, it is accepted that the establishment of requested new communication connections in a peripheral module is delayed by about 500 ms. As described above, the connection data of about 30 existing communication connections can be read and the corresponding hardware settings checked, for example, within 500 ms. The check of the hardware creation is designated m in FIG. 1 with the reference character d, the new creation of communication connections m of the connection hardware HSIC with the reference character d '.

Before, during or after the reception of connection data of existing communication connections or the reception of connection data of new communication connections to be established, one is in each case in a further development Start impulse for a time interval measurement of fees dependent on the duration of the connection. If the respective connection data of such a communication connection is available to the connection manager COH, it sends the start pulse to the fee payer TM, which is provided in the interface module LIC2. Method step c shows the transmission of the fee payer start pulse for already existing communication connections and method step c 'shows the corresponding transmission of a start pulse for a new communication connection to be set up.

In a further development of the exemplary embodiment described with reference to FIG. 1 for the method according to the invention, in a method step (not shown) after method step a, the central switching computer MP transmits a request to the connection manager COH to terminate an existing communication connection. In the development of the exemplary embodiment, however, the fee payer start pulse according to method step c has not yet been transmitted from the connection manager COH to the fee payer TM at this time. The connection manager COH therefore does not confirm the request and does not carry out this request. This ensures that the fee payer TM can correctly determine the connection-dependent fees and does not receive a fee payer stop pulse before the receipt of a fee payer start pulse for an existing communication connection. Since the central switching computer MP has not received any confirmation from the connection manager COH, it repeats the transmission of the request to terminate the communication connection at preferably predetermined time intervals. In the meantime, for example between the first and the third transmission of the request, the connection manager COH has received the connection data of the communication association concerned and has sent a corresponding fee payer start pulse to the fee payer TM. He therefore acknowledges the third request with a confirmation, sends a charge counter stop pulse to the charge counter TM and terminates the communication connection by making appropriate hardware settings in the connection hardware ASIC.

In the exemplary embodiment described so far, it was assumed that there was a software error in the interface module LIC2. The same method and its developments can be used, for example, for the situation that a hardware error has occurred in the previously active interface module LIC1 and the 1 + 1 redundant interface module LIC2 has taken over the active function from the interface module LIC1. Furthermore, the same refinements of the method can be used in cases in which there is no redundant component or in which there is 1: N redundancy. All in all, there is therefore a universal method for eliminating a fault in an active peripheral module of a switching device, which allows all stable communication connections to be maintained after the fault has occurred, with at most short interruption times having to be accepted. Furthermore, the universal method guarantees the reliable deletion of all possibly incorrect data in the module, the establishment of new communication connections with the least possible time delay.

Claims

claims

1. A method to correct an error in an active Pe ^¬ ripheriebaugruppe (LiCl, LIC2) a switching device (EXC) in a communication system, especially in an ATM (Asynchronous Transfer Mode) communication system, wherein on the active peripheral assembly (LIC 1, LIC2) at least one signaled communication connection is conveyed and connection data of the communication connection are stored in the active peripheral module (LIC1, LIC2) in order to handle the communication connection, characterized in that after the occurrence of the error the connection data stored elsewhere is used in order to use the communication continue to handle communication link.

2nd Method according to claim 1, so that the connection data are stored in a central storage device (RHS) for a plurality of peripheral modules (LICl, LIC2) before the error occurs.

3. The method according to claim 1 or 2, characterized in that a redundant passive peripheral module (LIC2) is present for the active peripheral module (LICl), in which the connection data are stored redundantly.

4. The method according to any one of claims 1 to 3, wherein an error occurs in the software of the active peripheral module (LIC2), characterized in that after the occurrence of the error, the connection data stored elsewhere is transmitted redundantly into the still active peripheral module (LIC2) become.

5. The method according to any one of claims 1 to 3, characterized in that after the occurrence of the error, the previously active peripheral module (LICl) becomes passive and a redundant module is used as an active peripheral module (LIC2) into which the connection data stored elsewhere is transmitted become.

6. The method according to claim 4 or 5, characterized in that the connection data to be transmitted remain stored at the other location.

7. The method according to any one of claims 4 to 6, characterized in that the transmission of the connection data in the active peripheral module (LIC2) is interrupted or started at a later time in order to enable the establishment of new communication connections.

8. The method according to claim 7, characterized in that the connection data to be transmitted are transmitted in blocks to the active peripheral module (LIC2).

9. The method according to any one of claims 4 to 8, characterized in that already existing hardware settings in the active peripheral module (LIC2) after the at least partial transmission of the connection data are checked on the basis of the connection data obtained and corrected if necessary.

10. Switching device (EXC) for a communication system, in particular for an ATM communication system, with a central control unit (MP) for controlling a plurality associated peripheral modules (LIC 1, LIC 2), via which subscriber connections can be switched, characterized in that the central control unit (MP) has a data memory in which connection data transmitted via the assigned peripheral modules (LIC 1, LIC 2), signaled subscriber connections can be stored, and that a transmission unit (RHS) is provided for reading and transmitting the connection data to the assigned peripheral modules (LIC 1, LIC 2).