Abstract:
The invention relates to a method, whereby the decision as to whether a protocol conversion is required or not is made according to a target datum contained in a signaling message, it is decided whether. The generation of a signaling message according to another signaling protocol is only then carried out if it is absolutely necessary. Said measures enable data losses to be limited as a result of the protocol conversion. Furthermore, for example, the load on the protocol conversion unit is reduced.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is the US National Stage of International Application No. PCT/DE03/02698, filed Aug. 11, 2003 and claims the benefit thereof. The International Application claims the benefits of German application No. 10241197.2 DE filed Sep. 5, 2002, both of the applications are incorporated by reference herein in their entirety.  
       FIELD OF INVENTION  
       [0002]     The invention relates to a method, whereby signaling messages are received, which in each case contain a target datum. The target datum specifies a target device to which the signaling message is to be forwarded. Alternatively, the target datum allows the determination of a target device to which the signaling message is to be forwarded.  
       BACKGROUND OF INVENTION  
       [0003]     The signaling messages are transferred over a data transfer network according to various signaling protocols. The data transfer network is, for example, a data packet transfer network or a data transfer network, by which the data are transferred in time slots.  
         [0004]     The signaling relates in particular to instructions for the exchange of information, which relates to setting up, taking down and controlling a connection. At the same time, for example, the connection exists only at higher protocol levels, while the transfer of the operating data and the signaling data is connectionless at lower protocol levels. Another type of signaling messages are, for example, messages with which the connection status of a device is signaled to another device, without an operating data transfer connection to another device being required to exist.  
         [0005]     A signaling protocol is the body of control methods and operating instructions, according to which the signaling between two or more functional units working together is carried out. The protocols are customarily defined for a particular interface. All protocols of a communication connection form a so-called protocol stack.  
         [0006]     An interface is the junction between two systems and is defined at a logical or a physical level. Thus there is, for example, an interface between various telecommunication devices or interfaces for the connection of subscriber terminal equipment.  
         [0007]     If signaling messages are received according to various signaling protocols, then it would be possible to first convert the signaling messages into internal signaling messages that conform to a general signaling protocol in a central communication device for ensuring a unified processing of the signaling messages. The general signaling protocol would then have to include the superset of all necessary information elements. After the central processing of the signaling message, this would then be converted into a signaling message according to a signaling protocol of the target device.  
       SUMMARY OF INVENTION  
       [0008]     An object of the invention is to show a simple method for the forwarding of signaling messages, which in particular prevents data loss, which in particular can be carried out with a low device-related expense, and which in particular can be quickly implemented. Furthermore, a related program and a related device should be specified.  
         [0009]     The object related to the method is achieved by means of the method steps specified in the claims. Developments are specified in the dependent claims.  
         [0010]     The invention is based on the consideration that a conversion of signaling messages according to a signaling protocol into signaling messages according to another signaling protocol should then only be carried out if this is also absolutely unavoidable. Electronic circuits or processors are thus necessary for the conversion only for a portion of the signaling messages to be forwarded. Losses of data occur for many conversions, because a specific signaling message according to one signaling protocol cannot be converted into a signaling message with the same purpose according to the other signaling protocol. For the method according to the invention, these transformation errors occur only for a portion of the signaling messages to be forwarded.  
         [0011]     A converted signaling message is produced and forwarded for the method according to the invention in each case, depending on the target datum for signaling messages with a target datum, which specifies or relates to a target, which requires a protocol conversion. The converted signaling message is produced according to another signaling protocol as the signaling protocol of the received signaling message, taking into account the specifications for the conversion of the signaling messages from one signaling protocol into signaling messages of the other signaling protocol. In addition, the signaling messages are forwarded without conversion to another signaling protocol, depending on the target datum for signaling messages with a target datum, which specifies or relates to a target device, which does not require a protocol conversion. For an embodiment, without conversion to another signaling protocol also means that no conversion to an internal signaling protocol of the device used for the forwarding is carried out.  
         [0012]     Specifications for the conversion of the signaling messages are provided in international standards, for example. At the same time, signaling messages with the same or a similar target according to the target protocol of the conversion are produced, in principle, from signaling messages with a specific signaling target according to the original signaling protocol. Signaling data is customarily placed in different positions in the converted signaling message than in the received signaling message.  
         [0013]     For a development of the method according to the invention, the signaling messages are received from a signaling device, which controls the production and forwarding of a converted signaling message and the forwarding without conversion of the signaling protocol. The signaling device receives signaling messages from various communication devices, for example, from telephone terminal equipment, from data processing devices, from servers, from application programs or from network transfer devices between various data transfer networks. Additional central functions are also performed in the signaling device for a development, for example: 
    the protocol conversion,     the control of the access by terminal devices or central devices of local data transfer networks to a data transfer network, or     central switching tasks or forwarding tasks.    
 
         [0017]     By performing several functions in a signaling device, the functions can be performed in a simpler manner than in functional units physically separated from one another. In particular, no data transfer network is necessary for the communication between the individual functional units for performing the functions.  
         [0018]     A particular technical effect is achieved if the signaling units also perform functions of a telecommunication device, in particular switching functions in a telecommunication device network. The configuration expense for several hundred, several thousand or even several tens of thousands of terminal devices in a telecommunication device network is considerable. In the signaling device, this expense is required only once for an embodiment, centrally for all telecommunication devices of the network. If very many telecommunication devices are part of the network, then the configuration can also be stored as distributed into several central signaling devices, whereby however multiple stores of data in different signaling devices are avoided.  
         [0019]     If the signaling device performs functions of a telecommunication device, then telecommunication devices that signal according to various signaling protocols to other telecommunication devices can operate in the network. By means of the protocol conversion, signaling can also take place between telecommunication devices, which signal according to different signaling protocols or according to signaling protocols of various protocol families. In particular, the integration of telecommunication devices from various manufacturers into one telecommunication device network is thus made possible.  
         [0020]     For another development of the method according to the invention, the signaling device also performs the functions of a network access device for central devices for the provision of services for a multitude of terminal devices of several local data transfer networks. Examples of local data transfer networks are Ethernet networks or so-called token networks, which are optionally connected over so-called bridges or routers.  
         [0021]     Signaling data and operating data can thus be exchanged between the central devices of various local data transfer networks with the same and different data transfer methods, or with the same and different signaling methods.  
         [0022]     For an alternative development, the network access device contained in the signaling device performs a network access function for terminal devices of one or more local data transfer networks. Terminal devices are connected to the local data transfer network in one embodiment, which signals at higher protocol levels according to various signaling protocols.  
         [0023]     At a middle protocol level, the data transfer networks function by an embodiment according to the internet protocol.  
         [0024]     For a following development, signaling protocols to be used are: 
    protocols of the H.323 protocol family of the ITU-T (International Telecommunication Union—Telecommunication Standardization Sector), in particular the protocols H.225, H.245, H.450.x,     the SIP protocol (Session Initiation Protocol) of the IETF (Internet Engineering Task Force),     a signaling protocol for signaling between telecommunication devices, preferably the protocol QSIG. However, other signaling protocols are also used, to the extent that a protocol conversion is possible.    
 
         [0028]     For a following development, the target datum is read with an access function, which reads target data of various signaling protocols. This is possible if the access function determines the signaling protocol of the signaling message beforehand. This is made possible, for example, by the inclusion of data values or data structures typical for the protocol, or with the help of a protocol indicator in the signaling message. The protocol required by the target device specified by the target datum is subsequently determined. The decision about the necessity of a protocol conversion or about forwarding the signaling message without protocol conversion is then made on the basis of a comparison of the original signaling protocol and of the required signaling protocol. It is possible to make this decision in a simple manner by means of these method steps.  
         [0029]     For a following development of the method for the forwarding of signaling messages, no protocol conversion is required for signaling protocols of the same protocol family. At the same time, a specific basic protocol and its development, for example, belong to a protocol family.  
         [0030]     For a following development, the received signaling message is stored in a storage device. It is then decided whether a protocol conversion is or is not necessary. The stored signaling message is subsequently converted or forwarded without undergoing a protocol conversion. The use of a storage device is a simple means by which to store the signaling message until the decision about a protocol conversion or against a protocol conversion.  
         [0031]     For another development, the signaling message relates to signaling for the transfer of voice data or for the performance of an additional service feature with the transfer of voice data. The additional service features specify services that go beyond the simple transfer of voice data, e.g. forwarding of a call, a conference circuit or a call-back when busy. The method according to the development is particularly suited for the transfer of voice data in operating data packets, as is the case with internet telephony, which is also called VoIP (Voice over Internet Protocol).  
         [0032]     Furthermore, the invention relates to a program and a device for the implementation of the method according to the invention and its developments. For this reason, the above-named technical effects also apply for the program and for the device.  
         [0033]     For one embodiment, the device contains a protocol conversion device, which produces a signaling message with the same or at least similar control characteristics according to another signaling protocol from a signaling message according to a signaling protocol. Devices with such integrated protocol converters therefore function without external signaling network transfer devices or so-called border proxy servers. In this context, one also speaks of a “multi-protocol capability”. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0034]     Following are exemplary embodiments of the invention explained on the basis of the accompanying drawings. Shown therein:  
         [0035]      FIG. 1 a  forwarding device and an optional functional protocol conversion device,  
         [0036]      FIG. 2 a  network access device for servers for several local data transfer networks and a protocol conversion device contained in the network access device,  
         [0037]      FIG. 3 a  network access device for the terminal devices of a local data transfer network and a protocol conversion device contained in the network access device, and  
         [0038]      FIG. 4  method steps of a method for forwarding signaling messages with optional protocol conversion. 
     
    
     DETAILED DESCRIPTION OF INVENTION  
       [0039]      FIG. 1  shows a forwarding device  10  and a protocol conversion device  12  physically separated from it. The forwarding device  10  serves to forward signaling messages, which are sent to and from signaling devices A 1 , A 2 , A 3  and B 1 . The signaling devices A 1  to A 3  and B 1  are, for example, terminal devices, devices to which a multitude of terminal devices are connected, or devices that in turn forward the received signaling messages; see arrow  14  for the signaling device B 1 , for example.  
         [0040]     The signaling devices A 1  to A 3  send or receive signaling messages according to a signaling protocol Pa, which differs from a signaling protocol Pb, according to which the signaling device B 1  sends and receives signaling messages. Signaling messages according to the signaling protocols Pa and Pb are exchanged over transfer lines  16  to  22  between the signaling devices A 1  to A 3  and B 1  on the one side and the forwarding device  10  on the other side. The signaling messages according to the signaling protocols Pa and Pb can be converted with the help of the protocol conversion device  12  into corresponding signaling messages of the respective other protocol according to a prespecified transformation instruction.  
         [0041]     Furthermore, the forwarding device  10  has access to a storage device  30 , see arrow  32 , in which received signaling messages can be temporarily stored, until a decision about them has been made as to whether a protocol conversion is or is not necessary. Furthermore, the forwarding device  10 , for example, places inquiries with a path control device  34 , see arrow  36 , in order to determine the signaling unit to which a received signaling message must be forwarded.  
         [0042]     If the forwarding device  10  receives, for example, a signaling message from the signaling device A 2  at the signaling device A 3  over the transfer line  18 , then a control device of the forwarding device  10  determines that both signaling devices A 2  and A 3  signal according to the same signaling protocol. A protocol conversion is therefore not necessary. The signaling message received over the transfer line  18  is therefore forwarded without protocol conversion over the transfer line  20  to the signaling device A 3 , see dotted line  38 . Likewise, signaling messages for the signaling device A 2  coming from the signaling device A 3  over the transfer line  20  are forwarded without protocol conversion to the signaling device A 2 .  
         [0043]     However, if a signaling message intended for the signaling device B 1  is received in the forwarding device  10  from the signaling device A 1  over the transfer line  16 , then the control device of the forwarding device  10  establishes that the signaling device A 1  sending the signaling message and the signaling device B 1  receiving the signaling message signal according to different signaling protocols Pa and Pb. Therefore, the control device of the forwarding device  10  automatically incorporates the protocol conversion device  12  into the processing of the received signaling message. The received signaling message is sent from the forwarding device  10  to the protocol conversion device  12  over a transfer line  40 , and converted there into a signaling message according to the signaling protocol Pb. The protocol conversion device  12  subsequently sends the converted signaling message back to the forwarding device  10  over a transfer line  42 . The forwarding device  10  forwards the converted signaling message to the signaling device B 1  by using the path control device  34 .  
         [0044]     The incorporation of the protocol conversion device  12  into the forwarding is represented within the forwarding device  10  by means of dotted lines  44  and  46 . Likewise, signaling messages from the signaling device B 1  intended for the signaling device A 1  are forwarded according to the signaling protocol Pb from the forwarding device  10  to the conversion device  12 , converted there into signaling messages according to signaling protocol Pa, and forwarded to the forwarding device  10  as converted signaling messages. The forwarding device  10  then in turn forwards the converted signaling message to the signaling device A 1 .  
         [0045]      FIG. 2  shows a so-called trunking network access device  100 , which is also designated as a gatekeeper and performs the network access functions for servers  112 ,  116  and  120 . The servers  112 ,  116  and  120  perform services for terminal devices  102 ,  104 ,  106  and  108 , which in this sequence are arranged as subscribers TlnA, TlnB, TlnC and TlnD.  
         [0046]     The terminal devices  102  and  104  are connected to a local data transfer network  110 , to which the server  112  is also connected, which performs the functions of a telecommunication device. The terminal device  106  is connected to a local data transfer network  114 , for example, an Ethernet. Furthermore, the server  116  is connected to the local data transfer network  114 , which performs functions of a telecommunication device for the subscriber TlnC. The terminal device  108  is connected to a local data transfer network  118 , to which the server  120  is also connected, which performs the functions of a telecommunication device for the terminal devices of subscriber TlnD connected to the local data transfer network  118 .  
         [0047]     The local data transfer networks  110 ,  114  and  118  have, at most, a range less than ten kilometers, typically less than one kilometer and are, for example, placed inside a building. The local data transfer networks  110 ,  114  and  118  are connected with a wide area network  130  suitable for the transfer of voice data over transfer lines  122 ,  124  and  126  in this sequence, for example, with the internet functioning according to the internet protocol. The network access device  100  can also be achieved over the wide area network  130 . The wide area network  130  serves for data exchange over distances significantly greater than ten kilometers, typically over more than one hundred kilometers.  
         [0048]     Along with the network access device  100 , the servers  112 ,  116  and  120  perform the functions of telecommunication device network, which allows the subscribers TlnA to TlnD to call only over call numbers specified in the telecommunication network. For providing the functions of the telecommunication device network, the network access device  100  has access to a storage device  132  in which, on one hand, a table is stored, in which it is recorded which terminal device  102  to  108  is associated with which server  112 ,  116  or  120 . On the other hand, it is also recorded in the table which signaling protocol is used for signaling with the server  112 ,  116  or  120 . In the present exemplary embodiment, both of the servers  112  and  116 , for example, have been manufactured by the company SIEMENS AG, such that the signaling is carried out according to an in-house protocol for signaling between switching centers. This protocol is, for example, the protocol CorNetNQ, which is built on the protocol QSIG, which has been standardized by the ETSI (European Telecommunication Standard Institute). The servers  112  and  116  are, for example, of the type HiPath 3000, 4000 or 5000. The server  120  was in contrast manufactured by another company and signals in connection with the functions in the telecommunication device network according to the protocol H.323/H.450 or H.450.x, whereby x is a natural number for the designation of a special standard for a special additional service feature.  
         [0049]     In the exemplary embodiment, a signaling protocol of the protocol family H.323 is used, in particular the signaling protocols H.225 or H.245, as a signaling protocol between the servers  112 ,  116  and  120  on the one side and the network access device  100  on the other side.  
         [0050]     Although the signaling according to the protocol family H.323 is explained in detail in the relevant standards, several signaling messages are to be explained in the following in order to be able to better illustrate the relationship to the method according to the invention. It is assumed that the server  112  would like to send a signaling message to the terminal device  106  or to the server  116  responsible for this terminal device. In the server  112  it is not known that the terminal device  106  belongs to the server  116 . In addition, the address of the server  116  is not known in the server  112 . The server  112  sends an admission request message to the network access device  100 , which is confirmed with an admission confirmation message. After this, the server  112  directs a standard setup message according to H.323 to the network access device  100 . A CorNetNQ setup message is contained in the H.323 setup message. A so-called tunneling method is spoken of in this context, which is explained in the standard H.323 Annex M.1, for example.  
         [0051]     The H.323 setup message is transferred to the network access device  100 , see dotted line  134 . A control device of the network access device evaluates the H.323 setup message and at the same time establishes that this setup message contains a CorNetNQ message. The control device determines the terminal device specified in the CorNetNQ message or the server  116  specified in this message. Optionally, the sending server  112  or a terminal device  102 ,  104  originating the signaling message is also determined based on the received signaling message. With the help of the storage device  132 , it is then determined that no protocol conversion is necessary for the tunneled signaling message, because the server  116  can process signaling messages according to the signaling protocol CorNetNQ. The network access device  100  forwards an H.323 setup message to the server  116  on this basis. With the help of the tunneling method, the received CorNetNQ message is forwarded unmodified, i.e. directly, to the server  116  in the H.323 setup message without a protocol conversion being carried out, see dotted line  137 .  
         [0052]     The server  116  receives the H.323 setup message and processes the CorNetNQ message contained in it according to the protocol; at the same time, for example, a signaling button is activated on a display device of the terminal device  106 .  
         [0053]     However, if the server  112  sends an H.323 setup message with a tunneled CorNetNQ message, i.e. a setup message as well, which relates to the server  120  or the terminal device  108 , then it is determined in the network access device  100  that a protocol conversion is necessary for the tunneled signaling message according to the protocol CorNetNQ in a signaling message according to the signaling protocol H.323/H.450. The control device  136  therefore activates a protocol conversion device  138 , which converts the CorNetNQ message into an H.323 or H.450 signaling message with the same signaling target, and passes the converted signaling message back to the path control device  136 , see double arrow  140 .  
         [0054]     In the present exemplary embodiment, the path control device  136  sends an H.323 setup message received from the protocol conversion device  138 , which has a similar signaling effect to the CorNetNQ message. This message is sent to the server  120 , see dotted line  142 . The server  120  processes the H.323 setup message and carries out the related control action, for example, activation of a button at the terminal device  108 .  
         [0055]      FIG. 3  shows another exemplary embodiment with a network access device  150  for the terminal devices  152 ,  154  of a local data transfer network  155 . The terminal device  152  is used by a subscriber TlnE and signals according to the protocols of the protocol family H.323. The terminal device  154  is used by a subscriber TlnF and signals, for example, according to the protocol SIP. Nevertheless, both terminal devices  152  to  154  can exchange signaling data and operating data, because the network access device  150  also make possible a protocol conversion. For example, the terminal device  152  directs an H.323 setup message to the network access device  150 . The terminal device  154  is specified in the H.323 setup message as the target of the message. In order to transmit the H.323 setup message to the network access device  150 , an address of the network access device  150  known to the terminal device  152  is for example used for forwarding setup messages.  
         [0056]     The network access device  150  contains a decision device  156 , which determines whether a protocol conversion is or is not necessary with respect to the received signaling message. In the case of a signaling message from the terminal device  152  to the terminal device  154 , a protocol conversion is necessary. Therefore, the decision device  156  includes a protocol conversion device  158 , which produces a SIP invite message from the H.323 setup message, see double arrow  160 . The network access device  150  then sends the converted signaling message to the terminal device  154 . The terminal device  154  answers the network access device  150  according to the SIP protocol. The network access device  150  carries out a protocol conversion for the answer message and forwards the converted answer message to the terminal device  152 .  
         [0057]     However, if the terminal device  152  sends to the network access device  150  a signaling message that is intended for a terminal device that functions according to the H.323 protocol family, then the decision device  156  makes the decision that a protocol conversion is not necessary. The received signaling message is in this case forwarded to the target terminal device unmodified or in essence unmodified.  
         [0058]     For another exemplary embodiment, the network access device  150  is a component of a VoIP system  170 , which alongside the network access device  150  contains a telecommunication device functional unit  172 , which performs the functions of a telecommunication device. The system  170  performs the functions of an individual telecommunication device or is embedded in a telecommunication device network.  
         [0059]      FIG. 4  shows method steps of a method for forwarding signaling messages with optional protocol conversion. The method starts in a method step  180 . In a subsequent method step  182 , a signaling message according to an original signaling protocol is received.  
         [0060]     In a method step  184 , a target address is read from the original signaling message or determined on the basis of the information contained in the signaling message. In a method step  186 , depending on the target address and, for example, depending on the signaling protocol of the received signaling message, it is tested whether a protocol conversion is necessary. If this is the case, then a method step  188  follows directly after the method step  186 , in which the original signaling message is converted into a signaling message according to another signaling protocol. The converted signaling message is subsequently forwarded in a method step  190 .  
         [0061]     However, if it is determined in method step  186  that a protocol conversion is not necessary, then a method step  192  follows directly after the method step  186 .  
         [0062]     In method step  192 , the original signaling message is forwarded unmodified. The method is ended in a method step  194  both after the method step  192  as well as after the method step  190 .  
         [0063]     With the involvement of the forwarding device  10 , the network access device  100  or the network access device  150 , the method steps  180  to  194  are carried out with electronic circuits that contain no microprocessor, or through the execution of program instructions of a program or several programs by means of at least one microprocessor.  
         [0064]     Other signaling protocols instead of the mentioned signaling protocols are used for other exemplary embodiments.