Title of Invention	ARRANGEMENT AND METHOD RELATING TO LOAD DISTRIBUTION
Abstract	The present invention relates to an arrangement adapted to be provided in a server node (50) in a communication system, handling a large number of clients, comprising a number of interface boards (201,202,203) handling one or more protocols for communication with different nodes and a number of processing means (101,...,106) adapted to serve a plurality of clients which may use a number of different types of identities when addressing the server node (500). It comprises load distribution control means adapted to handle clients using at least two different categories of addressing identities separately, and to distribute the clients to processing means (101,...,106), and being adapted to provide a number of load index values (LI1-LI36), exceeding the number of processing means, and load index mapping means mapping between load index values and processing means in a load index mapping table (30,301,302,303,3011-3016). It is further adapted to distribute mapping tables or to substantially each interface board (201,202,203) and each processing means (101,...,106), and first mapping means comprising mapping algorithm (211,212,213) handling clients or subscribers using a first category of identity comprising a for the server node normal identity e.g. generated externally, said mapping algorithm being adapted to establish a load index value (LI1) for an incoming message using said first category of identity, and second mapping means (221,222,223) comprising a second mapping algorithm for mapping second category or internally generated identities to respective load index values such that a client will be handled by the processing means (101,...,106) mapped to the corresponding, established load index value.

Title of Invention

ARRANGEMENT AND METHOD RELATING TO LOAD DISTRIBUTION

Abstract

The present invention relates to an arrangement adapted to be provided in a server node (50) in a communication system, handling a large number of clients, comprising a number of interface boards (201,202,203) handling one or more protocols for communication with different nodes and a number of processing means (101,...,106) adapted to serve a plurality of clients which may use a number of different types of identities when addressing the server node (500). It comprises load distribution control means adapted to handle clients using at least two different categories of addressing identities separately, and to distribute the clients to processing means (101,...,106), and being adapted to provide a number of load index values (LI1-LI36), exceeding the number of processing means, and load index mapping means mapping between load index values and processing means in a load index mapping table (30,301,302,303,3011-3016). It is further adapted to distribute mapping tables or to substantially each interface board (201,202,203) and each processing means (101,...,106), and first mapping means comprising mapping algorithm (211,212,213) handling clients or subscribers using a first category of identity comprising a for the server node normal identity e.g. generated externally, said mapping algorithm being adapted to establish a load index value (LI1) for an incoming message using said first category of identity, and second mapping means (221,222,223) comprising a second mapping algorithm for mapping second category or internally generated identities to respective load index values such that a client will be handled by the processing means (101,...,106) mapped to the corresponding, established load index value.

Full Text	FIELD OF THE INVENTION The present invention relates to an arrangement which is adapted to be provided in a server node for example in a telecommunication or a data communication system handling a large number of client or subscribers, comprising a number of interface boards handling one or more protocols, for communication with different nodes, node types and clients, and a number of processing means adapted to serve a plurality of clients or subscribers using a number of different types of identities when addressing the node. The identities or types of identities that are used when addressing the server node are particularly determined by the specific protocols. The invention relates to such an arrangement when clients or subscribers are handled generally for more than a single transaction. The invention also relates to a method for controlling the distribution of clients or subscribers communicating with a server node comprising a plurality of processing means, in for example a data communication system or a telecommunication system. The invention also relates to a server node comprising such an arrangement. STATE OF THE ART Telecommunication networks as well as data communication networks comprise a number of different server nodes each of which normally serve a very large number of clients or subscribers. Such server nodes generally interact with a plurality of different types of other nodes such as for example subscriber databases, service control nodes, gateways towards external networks etc. All these other types of nodes require communication over special types of physical interfaces which use special types of communication protocols. Messages received from such other nodes typically are addressed using various different identities which may serve as the identity of one and the same client or subscriber, i.e. how the subscriber or the client is identified, may depend on over which node or which node type communication takes place with a particular server node. Due to the fact that a server node generally handles a very large number of subscribers or clients, it comprises a number of different processing means, e.g. processors such as CPUs etc, it is of utmost importance, i.e. it is crucial to the system, that such server nodes can 2 remain in service, i.e. function, also when there are software or hardware failures. In order to achieve scalability while still maintaining proper fault encapsulation, it is attractive, or known, to base the system architecture of such server nodes on an extendible set of loosely coupled processing means. Preferably the clients or subscribers should then be distributed as evenly as possible over the available processing means in the server node. However, for the first it is difficult to provide an even distribution of the load, i.e. of subscribers or clients, among the available processors. Second, it is very problematic to handle the situation in case of software or hardware failure and for example take care of the situation when one or more processors goes down etc, but also when an "up-scaling" is needed, i.e. addition of one or more further processors. This particularly gets complicated due to the fact that addressing and distribution to processing means gets so complicated, particularly since one and the same client or subscriber may be identified using different types of identities. In one simple implementation of a load distribution scheme wherein the clients are distributed more or less evenly over the available processors, a solution may be provided which either is non-redundant or which is not scalable. One of the reasons therefor is that, as referred to above, incoming messages from external nodes concerning a particular subscriber or client have to be routed to the correct processing means that handles that subscriber or client. Hence, at the point where the messages are decoded in the sense that an identity is extracted which identifies the client, there must be some way to map the extracted identity to the appropriate processor. This could be done by maintaining the mapping between identity and processing means in a table that is maintained in a node. This will however lead to a single point of failure and a bottleneck, which means a non- redundant solution, or the mapping has to be replicated. However, if the mapping has to be replicated, replication or replicas have to be synchronized every time an identity is added for a client. It is not feasible to provide for updating and redundancy each time there is a new subscriber identity, particularly if the number of clients or subscribers is very high. On the other hand, if there is only one table and if there is a failure, all information will be lost. It is obvious that serious problems are associated with the handling of a large number 3 of subscribers or clients, for example even up to a million subscribers in one single server node comprising a number of processing means. However, also with a considerably lower number of subscribers, the situation is problematic and so far there has been no satisfactory solution to the above mentioned problems. SUMMARY OF THE INVENTION What is needed is therefore an arrangement for distributing clients or subscribers as initially referred to which enables scalability. Further an arrangement is needed through which redundancy can be provided for. Still further an arrangement is needed which is fault tolerant and which efficiently can handle situations when one or more processors disappear or appear. Still further an arrangement is needed through which it is possible to distribute load, i.e. clients or subscribers, evenly among the available processing arrangements in server node. Particularly an arrangement is needed through which subscribers or clients can be distributed in a desired manner among processing arrangements, or in a way which is appropriate with respect to the current number of available processing means. Still further an arrangement is needed which is robust to hardware failures. Most particularly an arrangement is needed through which clients or subscribers can be routed to the correct processor or processing means handling the client or subscriber, irrespectively of which is the protocol the subscriber or client is communicating over and independently of which identity, which particularly may be protocol specific, that currently is used such that the subscriber or client always will always be handled or directed to one and the same processor or redistributed due to the current load situation or for reasons of a software failure in the node. Particularly an arrangement is needed through which routing to the appropriate processing means, irrespectively of the actual identity used to identity a subscriber or client, can be done without the use of a table mapping each identity to a processing means. In addition thereto an arrangement is needed through which subscribers or clients can be routed or handled by the appropriate processing arrangement even if the clients or subscribers are addressing the node over different protocols which hence can be addressed using different 4 types of identity for one and the same subscriber. Particularly an arrangement is needed through which clients simply can be identified irrespectively of which type of identity that is used. Even more particularly an arrangement is needed which functions in a distributed execution environment despite individual processing means or interface units being temporarily or permanently lost and irrespectively of whether there is a very large number of subscribers or clients. Therefore a method as initially referred to is also needed through which one or more of the above mentioned objects can be achieved. Still further a server node is needed through which one or more of the objects referred to above can be achieved. Therefore an arrangement as initially referred to is provided which comprises load distribution control means adapted to handle at least clients or subscribers using two different categories of identities separately and appropriately distributing them to processing means. Such load distribution control means are adapted to provide a number of load index values, said number considerably exceeding the number of processing means, load index mapping means (LIM), e.g. a table, adapted to provide a mapping between load indices and processing means and said load distribution control means further comprises first mapping means handling clients or subscribers using a first category of identity comprising a, for the node, normal identity, (e.g. generated externally of the arrangement or the server node), said first mapping means comprising a mapping algorithm adapted to establish a load index value (LI1) for incoming messages identifying a client or subscriber with a first category identity, and still further it preferably comprises internal identity generating means for generating identities for incoming messages using at least one other category of identity. It also comprises second mapping means comprising a second mapping algorithm for establish a load index value (LI11) for such second category, e.g. internally generated identities. It should however be clear that internal identity generating means may be provided in the arrangement, e.g. in the processing means, in separate means of the arrangement, on separate boards, or as an arrangement(s) in communication with but externally of the arrangement. 5 The load distribution control means are furthermore adapted to distribute the mapping table to each interface board and to each processing means. A client or a subscriber identified through a first normal identity or a second internally generated identity is handled by the processing means given by the corresponding established load index. Particularly the load index mapping means are adapted to map load indices to processing means according to given criteria. In a preferred implementation the load index mapping means are adapted to map load indices to processing means such that a substantially even load distribution among the processing means is obtained (also when processing means appear or disappear). Preferably the number of load indices available for mapping to processing means is much higher than the number of processing means, particularly it comprises substantially p2, or at least p2 , p being the number of processing means in the server node. Generally, the higher the number of load indices, the better. Anyhow, the main thing is that the number considerably exceeds p. Particularly the mapping table is updated, e.g. reestablished or recomputed, when the number of available processing means is changed, e.g. one or more processing means is added and/or removed, e.g. malfunctioning. Particularly, in one embodiment, the first category of identities (normal identities), in e.g. GPRS (GSM Packet Radio Service) comprise subscriber IMSIs (International Mobile Subscriber Identity). However, it should be clear that normal identity here is taken to mean an identity that is normal for the server node, and unique for a subscriber or client e.g. for SGSNs, MSC, HLR it may be IMSI. For an EIR (Equipment Identity Register) it would be IMEI (International Mobile Equipment Identity) etc. Particularly said second category of identities comprise internally generated identities used when replacing identities in messages from external network elements e.g. GGSNs, SCPs, MSs/UEs, SGSNs, MSCs, RNCs (for GPRS) etc. concerning a specific client or subscriber. Particularly said second category of identities comprise internal identities, particularly internally generated identities replacing TMSI (Temporary Mobile Subscriber Identity), P-TMSI (Packet TMSI), transaction identities etc. and particularly said identity generating means are adapted to generate an internal identity to replace such 6 identities, said internally generated identity subsequently being used in all messaging with (to/from) external network elements. An external network element is here taken to mean any node e.g. a GGSN, an SCP, a MSC, an RNC etc. (for GPRS) or the client or subscriber itself. In a particular implementation the arrangement is adapted to handle at least a third category of identities in addition to said first and second categories separately and/or differently from said first and second categories of identities. Particularly said third category of identities comprise identities used in spontaneous messages from an external network element not comprising the normal identity of the subscriber or client or occurring with a very low frequency, e.g. client or subscriber hardware specific identities such as IMEI, of course unless IMEI is the normal identity, e.g. if the server node is an EIR as discussed above. Particularly the arrangement is adapted to send a broadcast to all processing means in order to allocate a processing means or the appropriate processing means to a message, or a subscriber or client identified through an identity of said third category which, as referred to earlier in the application occurred with a very low frequency which makes the procedure of making a broadcast to all the processors a viable strategy. Preferably first and second mapping means are provided in each interface board, hence increasing robustness and fault-tolerance. In a particular embodiment interface boards and processing means are disposed separately. Alternatively processing means and interface boards are co-located. In a particular implementation the load distribution control means comprises a centralized object for computing, maintaining and distributing the load index table to all interface boards and to all processing means in the server node. According to an advantageous implementation of the inventive concept, said identity generating means comprises an identity category specific server for each category of identities received and for which internal identities are to be generated. Even more 7 particularly each identity specific server means cooperates with or is integrated with a corresponding second mapping algorithm dedicated for a specific category of identities such that mapping can be performed between a generated identity and a load index. The identity generating means or identity specific servers are particularly provided in the processing means. The processing means particularly comprise control processors. In a particularly advantageous implementation the first mapping algorithm for mapping between a normal identity and a load index comprises a Hash algorithm for example using a Modulo operation. The inventive concept is basically based on the assumption that each subscriber or client only comprises one normal identity which however has to be normal with reference to the server node. For some other node, another identity or identity category/type may be the normal one. The arrangement according to the inventive concept is according to different embodiments adapted to be provided in an SGSN (Serving GPRS Support Node), a GGSN (Gateway GPRS Support Node), a Web server, an RNC (Radio Network Control node), an MSC (Mobile Switching Center), an HLR (Home Location Register), a node in an IMS (Internet Multimedia Subsystem), an SCP (Service Control Point) etc. or any server node handling many clients or subscribers, at least most of them during more than one transaction such that it gets important to be able to route clients or subscribers to the correct processing means handling that subscriber independently of which identity or category of identity that is used for the subscriber for example depending on over which node it accesses the server node or if it accesses it directly, spontaneously, non-spontaneously etc. In a particular implementation the arrangement is adapted to transfer a client or a subscriber for which an internal identity has been generated to replace the internal identity, for example P-TMSI, if the arrangement subsequently receives information from the network about the normal identity of the client or subscriber. This is particularly performed through internal signalling between processing arrangements. 8 Preferably, the arrangement is adapted to, if a client or subscriber has a normal identity, and the arrangement gets knowledge about the normal identity of the subscriber, always generate/find a load index mapped to the normal identity. The invention also suggests a server node for example in a telecommunication system or a data communication system, such as an SGSN, a GGSN, a CGSN, a HLR, an RNC, an MSC, a Web server, an IMS node etc. which comprises an arrangement as described with reference to one of the embodiments discussed above. Preferably each interface board comprises a first mapping means, a second mapping means and a LIM table. Further, preferably each processing means comprises internal identity generating means. The invention also suggests a method as initially referred which comprises the steps of; establishing whether a message received on an interface board is addressed using a, for the server node, normal, singular or proprietary, identity specific for the subscriber or client, if yes, mapping the normal identity to a load index in a first mapping means using an algorithm, and mapping the load index to a processing means using a mapping table provided in the interface board; if not, providing or generating an internal identity for a subscriber or client establishing a connection directly or indirectly over an external node over an interface board using another type or category of identity, or if it is a message addressing a client/subscriber using an already internally generated identity; mapping the internally generated identity to a load index in a second mapping means using an algorithm; mapping the load index to a processing means using the mapping table provided in the respective interface board. Advantageously the method comprises the step of; sending a broadcast message to all processing means in the server node upon reception of a spontaneous message from an external network element e.g. an external node or a 9 subscriber/client with an identity of a category, or type, that is set externally, i.e. not generated internally, and not a normal identity, and occurring with a very low frequency. Preferably the message further comprises the step of; computing or establishing a load index-to-processing means mapping table in the server node, for example in a centralized object; distributing the load-index-to-processing means mapping table to all interface boards and processing means in the server node. Even more particularly the method comprises the step of; designating a number of load indices which number considerably exceeds the number p of processing means, preferably exceeding p2. According to one embodiment the normal identity is the subscriber IMSI, and the server node some kind of a GPRS node. Preferably the method further comprises the step of; updating, e.g. re-computing, and redistributing, the load-index-to-processing means mapping table when a processing means is added, e.g. appears, or disappears, e.g. is malfunctioning or similar. The distributing steps particularly comprises; distributing the load, i.e. the clients or subscribers substantially evenly among the available processing means. In an alternative implementation the mapping comprises the step of distributing the load according to some given criteria, for example unevenly, among the processing means which hence is done, or how, is determined upon creation of the load index-to-processing means mapping table. In a particular implementation the first mapping means comprises a mapping algorithm comprising a Hash function e.g. implementing a Modulo operation. Other types of Hash functions, for example more advanced Hash functions may also be used as well as entirely different algorithms. 10 The method further particularly comprises the step of; using a reference identity or the internally generated identity or a reference identity for all subsequent communication concerning the client or subscriber in question through which the load index can be deduced or extracted, allowing for routing to the appropriate routing means from external network elements. BRIEF DESCRIPTION OF THE DRAWINGS The invention will in the following be further described, in a non-limiting manner, and with reference to the accompanying drawings, in which: Fig. 1 shows an example of an arrangement according to the invention implemented in a server node, Fig. 2 illustrates generation of internal identities in the server node according to one embodiment of the invention, Fig. 3 schematically illustrates the handling of messages with a normal identity and internally generated identities respectively in the server node, Fig. 4 illustrates a server node handling a message addressed on a normal identity for a known client, Fig. 5 illustrates a server node handling a message addressed on a normal identity for an unknown client, Fig. 6 illustrates a server node handling a message addressed on an internally generated identity for a known client, Fig. 7 illustrates the procedure in a server node initiating a dialogue with an external network concerning a specific subscriber, 11 Fig. 8 illustrates an exemplary procedure in a server node when an initiating message is not addressed using a normal identity, Fig. 9 is a flow diagram showing one implementation of a procedure and according to the inventive concept. DETAILED DESCRIPTION OF THE INVENTION Fig. 1 shows a server node 500, for example a 3GGP HLR. It should however be clear that it could be any other node as well, as discussed earlier in the application. Here it is supposed that server node 500 comprises a number of processors P1 101, P2 102, P3 103, P4 104, P5 105, P6 106 and a number of interface boards 201, 202, 203. It should be clear that the number of processors, particularly control processors, and the number of interface boards merely are given as an example; generally there are much larger numbers of processors as well as interface boards since the node can handle a very large number of clients or subscribers. It should however be clear that the inventive concept is applicable also when the number of clients or subscribers is lower. Each interface board 201, 202, 203 can handle messages using many different protocols and generally the way a client or a subscriber is identified is determined by the particular protocol used which also depends on from which node a message is coming or if it comes from the client directly etc. It is supposed that the server node comprises means, here for explanatory reasons illustrated as a list 31, with load index values. Normally the number of load index values shall be much larger than the number of processors involved. In an advantageous implementation it is the square of the number of processors, in this case it would hence be 36 different load index values since there are 6 processors. In another embodiment, however, the number of load index values that are used is higher than that, but it may also be somewhat lower. The main thing being that it considerably exceeds the number of processors in the server node, normally the more, the better. The node also comprises a load index-to-processor mapping table 30, in the following denoted LIM, in which a mapping is provided between processors and load index values. In this 12 very simple example it is supposed that the first six load indices LI1,..., LI6 are mapped onto processor PI etc. and finally load indices LI31,..., LI36 are mapped onto processor P6. It should be clear that this is merely one simple illustration of how the concept can be implemented. In a preferred implementation LIM is computed in a centralized object in the server node 500. LIM 30 is then distributed to each processor P1-P6 and to each interface board 201, 202, 203. In one implementation replicas of a LIM are provided in the processors and in the interface boards respectively. LIM 30 is most advantageously recomputed and redistributed to the processors and to the interface boards respectively when, and only when, a processor appears or disappears. However, if it is known that a very large number of subscribers or a particular group of subscribers or series of subscribers disappears or appears, LIM may also be recomputed and redistributed etc. Preferably the load indices are evenly distributed over the processors P1-P6. However, particular control means could also be provided to enable any other desired load distribution. Each interface board 201, 202, 203 comprises first mapping means 211, 212, 213 for mapping messages identifying a client or subscriber by means of an identity that is normal for the server node 500 to a load index. Each interface board also comprises second mapping means 221, 222, 223 for mapping messages identifying a client or subscriber through some other category or type of identification, here particularly through an identity or identity type that has been generated internally in the server node 500 itself. The first and second mapping means in each interface board both communicate with the respective LIM table 301, 302, 303 provided in each interface board as discussed earlier. In the respective load index mapping means 301, 302, 303 respective messages received on the interface board and mapped to a load index in a first or a second mapping means, are through the load index mapped to a processor as given by the LIM 30 from which the information also is provided. Hence, through the respective relevant mapping in LIM 301, 302, 303 a message with a normal identity or some other identity can be mapped to the appropriate processor. 13 However, each processor here P1-P6 comprises internal identity generating means 401, 402,...., 406 in which an internal identity can be generated for a message incoming using some other identity than a normal identity, for example a non-spontaneous messages from an external network element regarding a particular client or subscriber handled by the server node during a preceding establishment of a connection between the server node and the external network element during which procedure the server node, e.g. by means of an internal identity generator in a respective processor provides the external network element with a reference identity, here called an internally generated identity, for the particular client or subscriber and which internal identity then is used in the message to be input to an interface board, as well as for routing of subsequent messages. In the following some different cases will be in discussed, namely when a message is incoming which is identified through a normal identity, and when a message is incoming being identified through an internally generated identity and the case when a message is incoming which is identified through the same type of identification as an internally generated identity but for which the server node later receives information about the normal identity from the network. For illustrative purposes simplified examples will be given and described relating to how messages identifying the respective clients in different manners can be handled according to the inventive concept. Hence, it is supposed that a message M(NIDX) is incoming to interface board 203. Since it is a message using a normal identity it is handled in the first mapping means 213. It is here supposed that the normal identity M(NIDX) is mapped to a load index LI35. This mapping can be performed through e.g. a simple Hash algorithm e.g. a Modulo operation. Once the load index is found, a mapping to a processor is performed in the LIM 303 also provided in the interface board 203. The content in the LIM replica 303 of course is the same as in LIM 30, but for reasons of clarity the whole LIM table cannot be illustrated in the figure. LI35 is here hence mapped to P6 and the message with identity NIDX is routed to P6. The sending of the message can be handled by separate means, by the LIM 303 or by the first mapping means 213; it is merely schematically illustrated in this figure as taking place from LIM 303. Also P6 106 contains a LIM 3016 so that it will be 14 aware of which load indices that are handled by itself (and also by the other processing means). It is supposed that the internal identity generating means 406 provides for extraction of a reference identity containing the load index or through which the load index somehow can be easily extracted, which then is transferred to the external network element such that also for future communication the subscriber here identified by NIDX will be handled by P6 106. It is also supposed that a message with an identity which is a so called internally generated identity arrives to another interface board 202. The internal identity is here indicated Miiy, wherein iiy is taken to mean a, by the server node 500, internally generated identity. It is supposed that the internal identity has been generated during a preceding handshaking procedure, or during a connection establishment with one of the processing means P1-P6. This procedure will however not be explained with reference to this figure but it is simply supposed that the message is incoming to interface board 202, and since it is a message of a second category of identity, i.e. not a normal identity, it is handled by the second mapping means 222 wherein a mapping algorithm, which particularly is simpler than the one used in the first mapping means, since the identity already was generated internally, maps it to a load index. In this particular case it is supposed that iiy is mapped to load index LI24. Since the internal identity was already generated internally in the server node, the load index can easily be identified or extracted out of the internal identity. Using LIM 302 in interface board 202, it can be seen that LI24 is handled by P4, and hence the message with the internal identity iiy is sent to P4. Further it is supposed that an incoming message MiZ is received in interface board 201. It is here supposed that the client is not identified by the normal identity but with an identity that is similar to an internal identity, and it will hence be handled in the second mapping means 221 and mapped onto (here) LI12 which, using LIM 301 is established to be handled by P2 102. The message with identity yz is sent to P2. However, yz was not really an identity generated internally in the node but an identity of a similar type, for example a P- TMSI. Later on P2 102 is made aware of the fact that the client identified through yz 15 actually has a normal identity NIDZ and then it is established which load index that identity corresponds to or is mapped to and if it is not the same load index or another load index handled by P2, the message or client is transferred to, in this case, P3 which is the processing means that handles the load index which NIDZ is mapped to (which e.g. is established in LIM 3012 in communication with a first mapping means). The procedure of providing an internal identity as well as the procedure of allocating such messages and a message with a normal identity will now be explained with reference to Figs. 2 and 3 according to one embodiment. As referred to above, according to the present invention it gets possible to distribute clients or subscribers substantially evenly over in a server node available processing means in such a way that incoming messages concerning a particular client can be routed to the processor handling that client without having to maintain an explicit table mapping the identity used in the incoming message to the processor, i.e. all identities to respective processors. The routing adapts to the disappearing and appearing of processors. It should be clear that, when discussing a server node here, the inventive concept is applicable to a large variety or different kinds of server nodes and different systems etc. An example is on 3GPP (Third Generation Partnership Project) nodes, such as BSC, RNC, MSC, SGSN, GGSN, CGSN, HLR, SCP as referred to above, but the concept is of course by no means limited to 3GPP nodes. Generally the inventive concept is based on the assumption that each client or subscriber has a unique normal identity, NID. The type of the normal identity is actually determined by the type of the server node, which here is expressed as "a for the server node normal identity". In an SGSN, MSC or HLR, the normal identity will typically be the IMSI (International Mobile Subscriber Identity) of a subscriber, whereas in an EIR (Equipment Identity Register) it would be the IMEI associated with the equipment, whereas for other types of nodes it might be the subscriber (MS) ISDN etc. It is further assumed that spontaneous messages from an external network element (NE) regarding a particular client or subscriber either are addressed using the normal identity of the client or the subscriber, or they occur with a very low frequency, i.e. a manual addition of an intercept case, where 16 many different types of identities may be used, for example IMEI or (MS) ISDN etc. depending on server node, which here makes a broadcast to all processors of a viable addressing strategy. It should be clear that this merely relates to specific implementations of the inventive concept and such messages, which are not addressed using the normal identity, or spontaneous, from an external network element and which occur with a very low frequency also can be handled in other manners; the inventive concept not being limited to any specific way for handling such messages, although, in one implementation it is indicated that they can be handled through using broadcast. Still further another assumption is that non-spontaneous messages from an external network element NE concerning a particular client or subscriber handled by the server node always are preceded by the establishment of a connection between the server node and the network element during which the server node provides the network element with a reference identity for the particular client or subscriber. This reference identity may then be used in all subsequent messaging from the external network element concerning the client or included in an internal identity generated by the server node actually forming the internal identity as discussed above and as also will be discussed more thoroughly below. According to the invention, and with reference also to Fig. 1, it is supposed that a list or a table or similar 31 is provided designating a range of load indices [0,..., n,] or as in Fig. 1, 1-36. To provide an optimal load balancing also when a processor disappears, n here preferably is in the order of p , p here being the number of processors in a maximum server node configuration. It should of course be clear that the number of load indices may be somewhat lower as well as somewhat higher or even much higher. Hence, the load index map (LIM) 30 maps load indices to processors particularly in such a way that the load indices are evenly distributed over the processors. However, also other distribution strategies are possible. As referred to above LIM is preferably maintained and computed by a centralized object in the server node and distributed to each processor, and also to each interface board. A further feature is that LIM is recomputed and redistributed only when a processor appears or disappears (and possibly when an interface board appears or disappears). 17 Particularly a designated normal identity mapping algorithm, in Fig. 3 denoted F can be selected as a first mapping means for mapping normal identities to load indices. When given a normal identity, the mapping algorithm F computes a load index. Preferably the mapping algorithm used in the first mapping means is selected in such a way that it with a high probability is capable to distribute any set of normal identities representative for a real population of clients or subscribers, preferably evenly, over the range of load indices. Any type of a simple Hash algorithm may for example be used. In one embodiment F(N)=(NmodK), where K is the number of load indices. In order to route an incoming message addressed using the normal identity, e.g. NID, to the appropriate processor, F(N) is used to map the NID to a load index, and then LIM is used to map the load index to a processor. For each type T of identities that are provided by the server node as client references to external nodes, i.e. for non-spontaneous messages form external network elements concerning a particular subscriber or client as referred to above, in one embodiment cf. Fig. 2, a designated identity server IST can be developed together with a T mapping algorithm GT. Hence, for any given load index L, IST will generate a unique identity I of type T, i.e. an IT, such that GT(IT)=L. Hence, IST can be used to generate a reference identity here called IT, for a client or subscriber C with normal identity NID N based on the load index F(N). Hence, GT(IT)=F(N). Thus, GT may be used for routing incoming messages addressed on identities of types T to the correct processors. IST may for example be realized by explicitly encoding, in each generated identity I, the load index LI, and a unique sequence number S. By maintaining a list of all allocated sequence numbers, a new unique identity may be generated from the next, non-allocated 18 sequence number. Further more GT is then simply implemented by extracting the explicitly encoded load index. This procedure is for example illustrated in Fig. 2 in which a message M[(IT1)] is generated by identity server IS(T1) in a processing means P55 in a server node 501, which message is sent to external network element NE 1 which responds with a message M[I(T1)] containing the identity generated by the identity server. Correspondingly for a message using an identity of type T2. It should be clear that the identity servers may be implemented in many different ways but particularly in each processing means. They may also be located in a centralized or partly distributed way in the server node. Hence, Fig. 3 schematically illustrates an example of reception of different types of messages while using a selected first or second mapping algorithm together with LIM to map to the correct processor where the subscriber or client is handled. In this embodiment processors P11-P15 are illustrated. Further a number of interface boards 201', 202', 203', 204' each handling different types of messages are disclosed. It is supposed that a message with a normal identity, here illustrated as M(N), is incoming on interface board 203'. The message is handled by a first mapping means 213' comprising a first mapping algorithm F(N) and mapped to a load index LI which in the LIM 303' table is mapped to processor P12. Hence message M(N) is routed to P12. It is also supposed that a response message M{I(T2)} is incoming on interface board 202', mapped to a load index LI in second mapping means 222' using a mapping algorithm for a type T2 messages, GT2(I(T2)). Then it is established in LIM 302' that the particular, found load index is handled by processor P14. Similarly, a response message M{I(T1)} incoming on interface board 2(V is handled in second mapping means 212' using a mapping algorithm for type T1 and established in LIM 301' to be handled by a processor P11. Fig. 4 schematically illustrates a server node 502 comprising a number of processing arrangements, here PA 1A-PK IK and a number of interface boards IBA 20A-IBN 20N. For reasons of clarity the centrally computed and maintained LIM table is not illustrated in the figure, reference is here made to Fig. 1. However, it is illustrated that replicas thereof or LIM tables are contained in all processing means and in all interface boards. The 19 intention of Fig. 4 is to explain the procedure, when, according to one embodiment, a message MSG M(N) using a normal identity for a client known to the server node 502 is incoming to an arbitrary interface, here IB 20N, (I1). Since M(N) contains a normal identity, it is handled by a first mapping algorithm F(N) in first mapping means 21N, as explained above, which maps the identity to a load index, here LIm, (21). In communication with the LIM table in IB 20N, it is established that LIm is handled by PK 1K and, here, the first mapping means 21N sends the message to PK 1K where there already is a context for handling the specific client with normal identity N and hence this context will handle message M (31). Fig. 5 is a figure similar to Fig. 4 for a case when a message M(N) is addressed using a normal identity N, received in an arbitrary interface board, here IB N, for an external network element NE for a client which is not known to the server node 502. In this figure similar reference numerals are used as in Fig. 4. Again the first mapping algorithm F(N) is used to map N to a load index, here found to be LIM. According to LIM, that load index LIM maps to server processor PK 1K (22). Therefore the message N is forwarded to processor PK 1K. In processor PK however there is no context for handling the client with NID N and therefore a context is created, (32). The created context then handles the message M(N). Fig. 6 is a figure similar to Figs. 4 and 5 illustrating a server node 503 with a number of processors, particularly control processors (as it can be in any one of the other embodiments as well) PA-PS, each with a LIM, and a number of interface boards, here IBA-IBQ 20A'-20Q' each with first mapping means 21A'-21Q', second mapping means 22A'-22Q' and a LIM. As in Fig. 4 and Fig. 5 the centrally computed LIM is not illustrated in the figure. In the embodiment described with reference to Fig. 6, it is supposed that a message M is addressed using an internal generated identity for a known client. Hence, it is supposed that message M (IT) addressed on IT is received on an arbitrary interface, here IBQ 20Q' from an external network element, (13). Since it is of type T, a second mapping means 22Q' with a second mapping algorithm GT is used to map IT to a load index, which here for example is supposed to be LI14 (23). According to LIM with which the second mapping means 22Q' communicates, LI14 is mapped to the server 20 processor PC. Hence, the message M (IT) is forwarded to PC (33). In processor PC there is a context for handling the client, since it was known, with identity IT and that context will handle message M. Fig. 7 again illustrates a server node 504 and an external network element NE. However, in this case it is supposed that a dialogue is initiated by the server node 504. Here it is supposed that the server node 504 comprises a number of processors PA-PR and a number of interface boards IBA-IBL 20A"-20L". Hence, it is supposed that processor PR initiates a dialogue with the external network NE regarding a certain client, (14), and an identity IT is included in the initiating message. IT is constructed in such a way that subsequent messages from the external NE can be correctly routed to the context of the client in PR. This is achieved by e.g. inserting the load index of F(N) in IT or by other means encoding F(N) in IT in such a way that it can be extracted from IT using an algorithm, wherein N is the normal identity of the client. Then the message is handled in the first mapping means 21L", where a mapping performed between the established load index, here for example LI25 and a processor PR having initiated the message that is handled by the first mapping means in for example IBL 21L". The message is then sent to the external network element including identity N2 and the external network element stores IT SO that it can be used as an address in subsequent messages to the server node 504, regarding the particular client. Fig. 8 shows a server node 505 comprising a number of processors P1-PK and a number of interface boards IBA-IBL 20A'"-20L'" and an external network element NE. In this case it is supposed that the initiating message from the external network element is not addressed on NID. Instead a message M (IT) is received on, here, interface board IBL 20L"', (15). Since it is not addressed using a normal identity, a second mapping means 22L"' comprising an algorithm GT is used to map IT to a load index LI, here it is supposed that it is mapped onto LI50 (25), and according to LIM, LI50 is mapped to processor PK. The message is then sent to PK but there is no context for handling a client with the identity IT in PK, therefore a context has to be created which subsequently will handle message M (35). However, in this case it is supposed that the internal identity actually was not an internally generated identity but just similar to that as to the type, and the client actually has a normal identity, and during the processing of the initiating message the normal 21 identity N of the client is received from the network. If F(N), or the corresponding load index is different from that handled by PK or any of the loading indices handled by PK, the context and the handling of the message is transferred (45), here, to a context for example in PA, which is established to be the right one. Finally Fig. 9 is a schematical flow diagram describing a procedure according to the inventive concept. However, the steps performed when a message is allocated on the "wrong" processor, c.f. Fig. 8, are not included. Hence, it is supposed that a message is received in an interface board of a server node (SN) from an external NE, 100. It is established if the client is identified through an identity which is normal for SN, 101. If yes, the mapping of the normal identity NID111x to a load index is done for example using a Hash function in the first mapping means of the receiving interface board, which mapping here is supposed to give the load index LI22, 102. Then the load index-to-processing means mapping table LIM provided on the interface board is used to map between the load index, here LI22, and processor, giving processor Pxy which hence is the processor handling the load index LI22, 103. Subsequently the message is sent to Pxy, 104, in any appropriate manner, and Pxy creates or establishes and sends a reference identity enabling recognition of the load index to the client and/or to the external network element to enable routing of the same client to Pxy in subsequent messaging, 105. If however, it was established that the client was not identified through an identity which is normal for SN, it is established whether the client is identified through an internal identity e.g. generated internally in SN, 101 A. (It should be clear that the establishment as to whether it is a normal identity or an internal or internally generated identity can be done simultaneously, or in another order, this is merely a schematical example.) If not, according to one implementation a broadcast can be sent to all processors in SN, 101B. If however it was established that the client was identified through an internally generated identity, a mapping of the internally generated identity to load index is performed in the second mapping means in the receiving interface board, for example through extraction of the relevant identity or reference identity, 102A. The load index to processor mapping 22 table LIM on the interface board is used to map between the found LI and processing means, here supposed to give processor Pxz, 103A. The message is thereafter sent to Pxz, 104A, and Pxz creates or establishes a reference identity enabling the recognition of LI to the client and all the external network elements to enable routing of the client to Pxz in subsequent messaging, case 105A. In this case it is easy since the message already was generated based on load index or a reference identity during previous generation for example during a handshake procedure or during establishment of a connection etc. It should be clear that the invention is not limited to the explicitly illustrated embodiments, but that it can be varied in a number of ways, be implemented in different kinds of systems, telecommunications systems, data communication systems and other systems whenever a server node is handling a large number of subscribers and comprises a number of processors and where an even or some other desired distribution of the load, for example clients or subscribers, is needed, and also when there, at least not as a general rule, is a question about single transactions. 23 WE CLAIM: 1. An arrangement adapted to be provided in a server node in a telecommunication or data communication system, handling a large number of clients or subscribers, comprising a number of interface boards handling one or more protocols for communication with different nodes, node types and clients and a number of processing means adapted to serve a plurality of clients or subscribers mostly for more than a single transaction and which may use a number of different types of identities when addressing the server node, characterized in that it comprises at least partly distributed load distribution control means adapted to handle clients or subscribers using at least two different categories of addressing identities separately, and to appropriately distribute the clients or subscribers to processing means, said load distribution control means being adapted to provide a number of load index values, said number exceeding the number of processing means, and comprising load index mapping means adapted to provide a mapping between load index values (LI1, LIII) and processing means, and to represent the mapping in a load index mapping table (LIM), and further being adapted to distribute such mapping tables or load index mapping table replicas to substantially each interface board and each processing means, and comprising first mapping means handling clients or subscribers using a first category of identity comprising a for the server node normal identity e.g. generated externally of the arrangement or the server node, said first mapping means comprising a mapping algorithm adapted to establish a load index value (LII) for an incoming message using said first category of identity, second mapping means comprising a second mapping algorithm for mapping second category or internally generated identities to respective load index values (Lin) such that a client or subscriber identified through a first normal identity or a second e.g. internally generated identity is handled by the processing means mapped to the corresponding, established load index value (LII, LIII). 2. An arrangement according to claim 1, characterized in 24 that the load index mapping means are adapted to map load indices to processing means according to given criterias. 3. An arrangement according to claim 1 or 2, characterized in that the load index mapping means are adapted to map load indices to processing means such that a substantially even load distribution among the processing means is obtained. 4. An arrangement according to any one of claims 1 -3, characterized in that the number of load indices available for mapping to processing means comprises substantially p2, or at least p2, p being the number of processing means in the server node or considerably exceeds p. 5. An arrangement according to any one of the preceding claims, characterized in that the mapping table is updated, e.g. re-established or recomputed, when the number of available processing means is changed, e.g. one or more processing means is added and/or removed. 6. An arrangement according to any one of the preceding claims, characterized in that the first normal category of identities comprises subscriber IMSIs. 7. An arrangement according to any one of the preceding claims, characterized in that said second category of identities comprise, for identities of non-spontaneous messages from external network elements, e.g. GGSNs, SCPs, MSs/UEs, SGSNs, MSCs, RNCs etc. concerning a specific client/subscriber, internally in the distributed load distribution control means generated identities. 25 8. An arrangement according to any one of the preceding claims, characterized in that it comprises, particularly in each processing means, internal identity generating means for generating identities intended at least for incoming messages or connection establishments using another, second, category of identity. 9. An arrangement according to any one of the preceding claims, characterized in that it is adapted to handle at least a third category of identities separately and/or differently from said first and second categories of identities. 10. An arrangement according to any one of the preceding claims, characterized in that the load distribution control means comprises a centralized object for computing, maintaining and distributing the load index mapping means (LIM), or the load index table. 11. An arrangement according to any one of the preceding claims, characterized in that the first mapping algorithm for mapping between a normal identity and a load index comprises a Hash algorithm, e.g. based on a Modulo operation. 12. An arrangement according to any one of the preceding claims, characterized in that it is adapted to be provided in an SGSN, GGSN, a CGSN, a Web server, an RNC, an MSC, an HLR, an IMS node, an EIR etc. or any server node handling many clients/subscribers generally during more than one transaction. 13. An arrangement according to any one of the preceding claims, characterized in that it is adapted to transfer a client or subscriber for which an internal identity has been generated based on e.g. a second category identity, e.g. P-TMSI, if the arrangement 26 subsequently receives information about the normal identity of the client/subscriber to the processing arrangement handling the load index to which said normal identity is mapped. 14. An arrangement according to any one of the preceding claims, characterized in that if a client/subscriber has a normal identity and the arrangement gets knowledge about the normal identity, it is adapted to always map the normal identity to a load index with the first mapping algorithm. 15. An arrangement according to any one of the preceding claims, characterized in that substantially each interface board comprises a first mapping means and a second mapping means. 16. An arrangement according to any one of the preceding claims, characterized in that each processing means comprises an internal identity generating means. 17. An arrangement according to any one of the preceding claims, characterized in that it is adapted to generate a reference identity based on the load index and/or through which the load index can be extracted for each normal identity and for each second or internally generated identity, and in that said reference identity is provided to the client or subscriber such that a client or user always can be directed or handled by the same processing arrangement in the server node. 18. An arrangement according to any one of the preceding claims, characterized in that the processing arrangements are integrated with processing boards. 27 19. A server node in a telecommunications system or a data communications system, e.g. a GGSN, a CGSN, an HLR, an SGSN, an RNC, an MSC, a WEB server, an IMS node etc, characterized in that it comprises an arrangement as in any one of claims 1-22. 20. A method for controlling the distribution of clients or subscribers communicating with a server node comprising a plurality of processing means in e.g. a data communications system or telecommunications system, characterized in that it comprises the steps of: establishing whether a message received on an interface board is addressed using a for the node normal identity specific for the subscriber or client, if yes, using an algorithm for mapping the normal identity to a load index in a first mapping means in the interface board, mapping the load index to a processing means using a mapping table provided in the interface board, or if it is addressed using an internal identity e.g. generated in the node, mapping the internal identity to a load index in a second mapping means using an algorithm, mapping the load index to a processing means using the mapping table provided in the interface board. 21. A method according to claim 20, characterized in that it comprises the step of: providing or generating an internal identity for a subscriber or client establishing a connection directly or indirectly over an external node over an interface board using another type or second category of identity, using an algorithm for mapping the internally generated identity to a load index in a second mapping means, 28 mapping the load index to a processing means using the mapping table provided in the interface board. 22. A method according to claim 20 or 21, characterized in that it comprises the step of: 29 using a reference identity based on the load index for the normal identity or the internally generated identity for all subsequent communication concerning the client or subscriber. The present invention relates to an arrangement adapted to be provided in a server node (50) in a communication system, handling a large number of clients, comprising a number of interface boards (201,202,203) handling one or more protocols for communication with different nodes and a number of processing means (101,...,106) adapted to serve a plurality of clients which may use a number of different types of identities when addressing the server node (500). It comprises load distribution control means adapted to handle clients using at least two different categories of addressing identities separately, and to distribute the clients to processing means (101,...,106), and being adapted to provide a number of load index values (LI1-LI36), exceeding the number of processing means, and load index mapping means mapping between load index values and processing means in a load index mapping table (30,301,302,303,3011-3016). It is further adapted to distribute mapping tables or to substantially each interface board (201,202,203) and each processing means (101,...,106), and first mapping means comprising mapping algorithm (211,212,213) handling clients or subscribers using a first category of identity comprising a for the server node normal identity e.g. generated externally, said mapping algorithm being adapted to establish a load index value (LI1) for an incoming message using said first category of identity, and second mapping means (221,222,223) comprising a second mapping algorithm for mapping second category or internally generated identities to respective load index values such that a client will be handled by the processing means (101,...,106) mapped to the corresponding, established load index value.

Full Text

FIELD OF THE INVENTION
The present invention relates to an arrangement which is adapted to be provided in a server
node for example in a telecommunication or a data communication system handling a
large number of client or subscribers, comprising a number of interface boards handling
one or more protocols, for communication with different nodes, node types and clients,
and a number of processing means adapted to serve a plurality of clients or subscribers
using a number of different types of identities when addressing the node. The identities or
types of identities that are used when addressing the server node are particularly
determined by the specific protocols. The invention relates to such an arrangement when
clients or subscribers are handled generally for more than a single transaction.
The invention also relates to a method for controlling the distribution of clients or
subscribers communicating with a server node comprising a plurality of processing means,
in for example a data communication system or a telecommunication system. The
invention also relates to a server node comprising such an arrangement.
STATE OF THE ART
Telecommunication networks as well as data communication networks comprise a number
of different server nodes each of which normally serve a very large number of clients or
subscribers. Such server nodes generally interact with a plurality of different types of other
nodes such as for example subscriber databases, service control nodes, gateways towards
external networks etc. All these other types of nodes require communication over special
types of physical interfaces which use special types of communication protocols. Messages
received from such other nodes typically are addressed using various different identities
which may serve as the identity of one and the same client or subscriber, i.e. how the
subscriber or the client is identified, may depend on over which node or which node type
communication takes place with a particular server node.
Due to the fact that a server node generally handles a very large number of subscribers or
clients, it comprises a number of different processing means, e.g. processors such as CPUs
etc, it is of utmost importance, i.e. it is crucial to the system, that such server nodes can
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remain in service, i.e. function, also when there are software or hardware failures. In order
to achieve scalability while still maintaining proper fault encapsulation, it is attractive, or
known, to base the system architecture of such server nodes on an extendible set of loosely
coupled processing means.
Preferably the clients or subscribers should then be distributed as evenly as possible over
the available processing means in the server node. However, for the first it is difficult to
provide an even distribution of the load, i.e. of subscribers or clients, among the available
processors. Second, it is very problematic to handle the situation in case of software or
hardware failure and for example take care of the situation when one or more processors
goes down etc, but also when an "up-scaling" is needed, i.e. addition of one or more
further processors. This particularly gets complicated due to the fact that addressing and
distribution to processing means gets so complicated, particularly since one and the same
client or subscriber may be identified using different types of identities.
In one simple implementation of a load distribution scheme wherein the clients are
distributed more or less evenly over the available processors, a solution may be provided
which either is non-redundant or which is not scalable. One of the reasons therefor is that,
as referred to above, incoming messages from external nodes concerning a particular
subscriber or client have to be routed to the correct processing means that handles that
subscriber or client. Hence, at the point where the messages are decoded in the sense that
an identity is extracted which identifies the client, there must be some way to map the
extracted identity to the appropriate processor. This could be done by maintaining the
mapping between identity and processing means in a table that is maintained in a node.
This will however lead to a single point of failure and a bottleneck, which means a non-
redundant solution, or the mapping has to be replicated. However, if the mapping has to be
replicated, replication or replicas have to be synchronized every time an identity is added
for a client. It is not feasible to provide for updating and redundancy each time there is a
new subscriber identity, particularly if the number of clients or subscribers is very high. On
the other hand, if there is only one table and if there is a failure, all information will be
lost. It is obvious that serious problems are associated with the handling of a large number
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of subscribers or clients, for example even up to a million subscribers in one single server
node comprising a number of processing means. However, also with a considerably lower
number of subscribers, the situation is problematic and so far there has been no
satisfactory solution to the above mentioned problems.
SUMMARY OF THE INVENTION
What is needed is therefore an arrangement for distributing clients or subscribers as
initially referred to which enables scalability. Further an arrangement is needed through
which redundancy can be provided for. Still further an arrangement is needed which is
fault tolerant and which efficiently can handle situations when one or more processors
disappear or appear. Still further an arrangement is needed through which it is possible to
distribute load, i.e. clients or subscribers, evenly among the available processing
arrangements in server node. Particularly an arrangement is needed through which
subscribers or clients can be distributed in a desired manner among processing
arrangements, or in a way which is appropriate with respect to the current number of
available processing means.
Still further an arrangement is needed which is robust to hardware failures. Most
particularly an arrangement is needed through which clients or subscribers can be routed to
the correct processor or processing means handling the client or subscriber, irrespectively
of which is the protocol the subscriber or client is communicating over and independently
of which identity, which particularly may be protocol specific, that currently is used such
that the subscriber or client always will always be handled or directed to one and the same
processor or redistributed due to the current load situation or for reasons of a software
failure in the node.
Particularly an arrangement is needed through which routing to the appropriate processing
means, irrespectively of the actual identity used to identity a subscriber or client, can be
done without the use of a table mapping each identity to a processing means. In addition
thereto an arrangement is needed through which subscribers or clients can be routed or
handled by the appropriate processing arrangement even if the clients or subscribers are
addressing the node over different protocols which hence can be addressed using different
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types of identity for one and the same subscriber. Particularly an arrangement is needed
through which clients simply can be identified irrespectively of which type of identity that
is used. Even more particularly an arrangement is needed which functions in a distributed
execution environment despite individual processing means or interface units being
temporarily or permanently lost and irrespectively of whether there is a very large number
of subscribers or clients.
Therefore a method as initially referred to is also needed through which one or more of the
above mentioned objects can be achieved. Still further a server node is needed through
which one or more of the objects referred to above can be achieved.
Therefore an arrangement as initially referred to is provided which comprises load
distribution control means adapted to handle at least clients or subscribers using two
different categories of identities separately and appropriately distributing them to
processing means. Such load distribution control means are adapted to provide a number
of load index values, said number considerably exceeding the number of processing
means, load index mapping means (LIM), e.g. a table, adapted to provide a mapping
between load indices and processing means and said load distribution control means
further comprises first mapping means handling clients or subscribers using a first
category of identity comprising a, for the node, normal identity, (e.g. generated externally
of the arrangement or the server node), said first mapping means comprising a mapping
algorithm adapted to establish a load index value (LI1) for incoming messages identifying a
client or subscriber with a first category identity, and still further it preferably comprises
internal identity generating means for generating identities for incoming messages using at
least one other category of identity. It also comprises second mapping means comprising a
second mapping algorithm for establish a load index value (LI11) for such second category,
e.g. internally generated identities. It should however be clear that internal identity
generating means may be provided in the arrangement, e.g. in the processing means, in
separate means of the arrangement, on separate boards, or as an arrangement(s) in
communication with but externally of the arrangement.
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The load distribution control means are furthermore adapted to distribute the mapping
table to each interface board and to each processing means. A client or a subscriber
identified through a first normal identity or a second internally generated identity is
handled by the processing means given by the corresponding established load index.
Particularly the load index mapping means are adapted to map load indices to processing
means according to given criteria.
In a preferred implementation the load index mapping means are adapted to map load
indices to processing means such that a substantially even load distribution among the
processing means is obtained (also when processing means appear or disappear).
Preferably the number of load indices available for mapping to processing means is much
higher than the number of processing means, particularly it comprises substantially p2, or
at least p2 , p being the number of processing means in the server node. Generally, the
higher the number of load indices, the better. Anyhow, the main thing is that the number
considerably exceeds p.
Particularly the mapping table is updated, e.g. reestablished or recomputed, when the
number of available processing means is changed, e.g. one or more processing means is
added and/or removed, e.g. malfunctioning. Particularly, in one embodiment, the first
category of identities (normal identities), in e.g. GPRS (GSM Packet Radio Service)
comprise subscriber IMSIs (International Mobile Subscriber Identity). However, it should
be clear that normal identity here is taken to mean an identity that is normal for the server
node, and unique for a subscriber or client e.g. for SGSNs, MSC, HLR it may be IMSI. For
an EIR (Equipment Identity Register) it would be IMEI (International Mobile Equipment
Identity) etc. Particularly said second category of identities comprise internally generated
identities used when replacing identities in messages from external network elements e.g.
GGSNs, SCPs, MSs/UEs, SGSNs, MSCs, RNCs (for GPRS) etc. concerning a specific
client or subscriber. Particularly said second category of identities comprise internal
identities, particularly internally generated identities replacing TMSI (Temporary Mobile
Subscriber Identity), P-TMSI (Packet TMSI), transaction identities etc. and particularly
said identity generating means are adapted to generate an internal identity to replace such
6

identities, said internally generated identity subsequently being used in all messaging with
(to/from) external network elements. An external network element is here taken to mean
any node e.g. a GGSN, an SCP, a MSC, an RNC etc. (for GPRS) or the client or subscriber
itself.
In a particular implementation the arrangement is adapted to handle at least a third
category of identities in addition to said first and second categories separately and/or
differently from said first and second categories of identities. Particularly said third
category of identities comprise identities used in spontaneous messages from an external
network element not comprising the normal identity of the subscriber or client or occurring
with a very low frequency, e.g. client or subscriber hardware specific identities such as
IMEI, of course unless IMEI is the normal identity, e.g. if the server node is an EIR as
discussed above.
Particularly the arrangement is adapted to send a broadcast to all processing means in
order to allocate a processing means or the appropriate processing means to a message, or
a subscriber or client identified through an identity of said third category which, as referred
to earlier in the application occurred with a very low frequency which makes the procedure
of making a broadcast to all the processors a viable strategy.
Preferably first and second mapping means are provided in each interface board, hence
increasing robustness and fault-tolerance. In a particular embodiment interface boards and
processing means are disposed separately. Alternatively processing means and interface
boards are co-located.
In a particular implementation the load distribution control means comprises a centralized
object for computing, maintaining and distributing the load index table to all interface
boards and to all processing means in the server node.
According to an advantageous implementation of the inventive concept, said identity
generating means comprises an identity category specific server for each category of
identities received and for which internal identities are to be generated. Even more
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particularly each identity specific server means cooperates with or is integrated with a
corresponding second mapping algorithm dedicated for a specific category of identities
such that mapping can be performed between a generated identity and a load index. The
identity generating means or identity specific servers are particularly provided in the
processing means. The processing means particularly comprise control processors.
In a particularly advantageous implementation the first mapping algorithm for mapping
between a normal identity and a load index comprises a Hash algorithm for example using
a Modulo operation. The inventive concept is basically based on the assumption that each
subscriber or client only comprises one normal identity which however has to be normal
with reference to the server node. For some other node, another identity or identity
category/type may be the normal one.
The arrangement according to the inventive concept is according to different embodiments
adapted to be provided in an SGSN (Serving GPRS Support Node), a GGSN (Gateway
GPRS Support Node), a Web server, an RNC (Radio Network Control node), an MSC
(Mobile Switching Center), an HLR (Home Location Register), a node in an IMS (Internet
Multimedia Subsystem), an SCP (Service Control Point) etc. or any server node handling
many clients or subscribers, at least most of them during more than one transaction such
that it gets important to be able to route clients or subscribers to the correct processing
means handling that subscriber independently of which identity or category of identity that
is used for the subscriber for example depending on over which node it accesses the server
node or if it accesses it directly, spontaneously, non-spontaneously etc.
In a particular implementation the arrangement is adapted to transfer a client or a
subscriber for which an internal identity has been generated to replace the internal identity,
for example P-TMSI, if the arrangement subsequently receives information from the
network about the normal identity of the client or subscriber. This is particularly
performed through internal signalling between processing arrangements.
8

Preferably, the arrangement is adapted to, if a client or subscriber has a normal identity,
and the arrangement gets knowledge about the normal identity of the subscriber, always
generate/find a load index mapped to the normal identity.
The invention also suggests a server node for example in a telecommunication system or a
data communication system, such as an SGSN, a GGSN, a CGSN, a HLR, an RNC, an
MSC, a Web server, an IMS node etc. which comprises an arrangement as described with
reference to one of the embodiments discussed above.
Preferably each interface board comprises a first mapping means, a second mapping means
and a LIM table. Further, preferably each processing means comprises internal identity
generating means.
The invention also suggests a method as initially referred which comprises the steps of;
establishing whether a message received on an interface board is addressed using a, for the
server node, normal, singular or proprietary, identity specific for the subscriber or client, if
yes, mapping the normal identity to a load index in a first mapping means using an
algorithm, and mapping the load index to a processing means using a mapping table
provided in the interface board; if not,
providing or generating an internal identity for a subscriber or client establishing a
connection directly or indirectly over an external node over an interface board using
another type or category of identity, or if it is a message addressing a client/subscriber
using an already internally generated identity;
mapping the internally generated identity to a load index in a second mapping means using
an algorithm;
mapping the load index to a processing means using the mapping table provided in the
respective interface board.
Advantageously the method comprises the step of;
sending a broadcast message to all processing means in the server node upon reception of a
spontaneous message from an external network element e.g. an external node or a
9

subscriber/client with an identity of a category, or type, that is set externally, i.e. not
generated internally, and not a normal identity, and occurring with a very low frequency.
Preferably the message further comprises the step of;
computing or establishing a load index-to-processing means mapping table in the server
node, for example in a centralized object;
distributing the load-index-to-processing means mapping table to all interface boards and
processing means in the server node.
Even more particularly the method comprises the step of;
designating a number of load indices which number considerably exceeds the number p of
processing means, preferably exceeding p2. According to one embodiment the normal
identity is the subscriber IMSI, and the server node some kind of a GPRS node.
Preferably the method further comprises the step of;
updating, e.g. re-computing, and redistributing, the load-index-to-processing means
mapping table when a processing means is added, e.g. appears, or disappears, e.g. is
malfunctioning or similar.
The distributing steps particularly comprises;
distributing the load, i.e. the clients or subscribers substantially evenly among the available
processing means.
In an alternative implementation the mapping comprises the step of distributing the load
according to some given criteria, for example unevenly, among the processing means
which hence is done, or how, is determined upon creation of the load index-to-processing
means mapping table.
In a particular implementation the first mapping means comprises a mapping algorithm
comprising a Hash function e.g. implementing a Modulo operation. Other types of Hash
functions, for example more advanced Hash functions may also be used as well as entirely
different algorithms.
10

The method further particularly comprises the step of;
using a reference identity or the internally generated identity or a reference identity for all
subsequent communication concerning the client or subscriber in question through which
the load index can be deduced or extracted, allowing for routing to the appropriate routing
means from external network elements.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will in the following be further described, in a non-limiting manner, and
with reference to the accompanying drawings, in which:
Fig. 1 shows an example of an arrangement according to the invention implemented in a
server node,
Fig. 2 illustrates generation of internal identities in the server node according to one
embodiment of the invention,
Fig. 3 schematically illustrates the handling of messages with a normal identity and
internally generated identities respectively in the server node,
Fig. 4 illustrates a server node handling a message addressed on a normal identity for a
known client,
Fig. 5 illustrates a server node handling a message addressed on a normal identity for an
unknown client,
Fig. 6 illustrates a server node handling a message addressed on an internally generated
identity for a known client,
Fig. 7 illustrates the procedure in a server node initiating a dialogue with an external
network concerning a specific subscriber,
11

Fig. 8 illustrates an exemplary procedure in a server node when an initiating message is
not addressed using a normal identity,
Fig. 9 is a flow diagram showing one implementation of a procedure and according to the
inventive concept.
DETAILED DESCRIPTION OF THE INVENTION
Fig. 1 shows a server node 500, for example a 3GGP HLR. It should however be clear that
it could be any other node as well, as discussed earlier in the application. Here it is
supposed that server node 500 comprises a number of processors P1 101, P2 102, P3 103,
P4 104, P5 105, P6 106 and a number of interface boards 201, 202, 203. It should be clear
that the number of processors, particularly control processors, and the number of interface
boards merely are given as an example; generally there are much larger numbers of
processors as well as interface boards since the node can handle a very large number of
clients or subscribers. It should however be clear that the inventive concept is applicable
also when the number of clients or subscribers is lower.
Each interface board 201, 202, 203 can handle messages using many different protocols and
generally the way a client or a subscriber is identified is determined by the particular
protocol used which also depends on from which node a message is coming or if it comes
from the client directly etc. It is supposed that the server node comprises means, here for
explanatory reasons illustrated as a list 31, with load index values. Normally the number
of load index values shall be much larger than the number of processors involved.
In an advantageous implementation it is the square of the number of processors, in this
case it would hence be 36 different load index values since there are 6 processors. In
another embodiment, however, the number of load index values that are used is higher
than that, but it may also be somewhat lower. The main thing being that it considerably
exceeds the number of processors in the server node, normally the more, the better. The
node also comprises a load index-to-processor mapping table 30, in the following denoted
LIM, in which a mapping is provided between processors and load index values. In this
12

very simple example it is supposed that the first six load indices LI1,..., LI6 are mapped
onto processor PI etc. and finally load indices LI31,..., LI36 are mapped onto processor P6.
It should be clear that this is merely one simple illustration of how the concept can be
implemented.
In a preferred implementation LIM is computed in a centralized object in the server node
500. LIM 30 is then distributed to each processor P1-P6 and to each interface board 201,
202, 203. In one implementation replicas of a LIM are provided in the processors and in the
interface boards respectively. LIM 30 is most advantageously recomputed and
redistributed to the processors and to the interface boards respectively when, and only
when, a processor appears or disappears. However, if it is known that a very large number
of subscribers or a particular group of subscribers or series of subscribers disappears or
appears, LIM may also be recomputed and redistributed etc. Preferably the load indices are
evenly distributed over the processors P1-P6. However, particular control means could
also be provided to enable any other desired load distribution.
Each interface board 201, 202, 203 comprises first mapping means 211, 212, 213 for
mapping messages identifying a client or subscriber by means of an identity that is normal
for the server node 500 to a load index. Each interface board also comprises second
mapping means 221, 222, 223 for mapping messages identifying a client or subscriber
through some other category or type of identification, here particularly through an identity
or identity type that has been generated internally in the server node 500 itself. The first
and second mapping means in each interface board both communicate with the respective
LIM table 301, 302, 303 provided in each interface board as discussed earlier. In the
respective load index mapping means 301, 302, 303 respective messages received on the
interface board and mapped to a load index in a first or a second mapping means, are
through the load index mapped to a processor as given by the LIM 30 from which the
information also is provided. Hence, through the respective relevant mapping in LIM 301,
302, 303 a message with a normal identity or some other identity can be mapped to the
appropriate processor.
13

However, each processor here P1-P6 comprises internal identity generating means 401,
402,...., 406 in which an internal identity can be generated for a message incoming using
some other identity than a normal identity, for example a non-spontaneous messages from
an external network element regarding a particular client or subscriber handled by the
server node during a preceding establishment of a connection between the server node and
the external network element during which procedure the server node, e.g. by means of an
internal identity generator in a respective processor provides the external network element
with a reference identity, here called an internally generated identity, for the particular
client or subscriber and which internal identity then is used in the message to be input to
an interface board, as well as for routing of subsequent messages.
In the following some different cases will be in discussed, namely when a message is
incoming which is identified through a normal identity, and when a message is incoming
being identified through an internally generated identity and the case when a message is
incoming which is identified through the same type of identification as an internally
generated identity but for which the server node later receives information about the
normal identity from the network.
For illustrative purposes simplified examples will be given and described relating to how
messages identifying the respective clients in different manners can be handled according
to the inventive concept. Hence, it is supposed that a message M(NIDX) is incoming to
interface board 203. Since it is a message using a normal identity it is handled in the first
mapping means 213. It is here supposed that the normal identity M(NIDX) is mapped to a
load index LI35. This mapping can be performed through e.g. a simple Hash algorithm e.g.
a Modulo operation. Once the load index is found, a mapping to a processor is performed
in the LIM 303 also provided in the interface board 203. The content in the LIM replica 303
of course is the same as in LIM 30, but for reasons of clarity the whole LIM table cannot
be illustrated in the figure. LI35 is here hence mapped to P6 and the message with identity
NIDX is routed to P6. The sending of the message can be handled by separate means, by the
LIM 303 or by the first mapping means 213; it is merely schematically illustrated in this
figure as taking place from LIM 303. Also P6 106 contains a LIM 3016 so that it will be
14

aware of which load indices that are handled by itself (and also by the other processing
means).
It is supposed that the internal identity generating means 406 provides for extraction of a
reference identity containing the load index or through which the load index somehow can
be easily extracted, which then is transferred to the external network element such that also
for future communication the subscriber here identified by NIDX will be handled by P6
106.
It is also supposed that a message with an identity which is a so called internally generated
identity arrives to another interface board 202. The internal identity is here indicated Miiy,
wherein iiy is taken to mean a, by the server node 500, internally generated identity. It is
supposed that the internal identity has been generated during a preceding handshaking
procedure, or during a connection establishment with one of the processing means P1-P6.
This procedure will however not be explained with reference to this figure but it is simply
supposed that the message is incoming to interface board 202, and since it is a message of a
second category of identity, i.e. not a normal identity, it is handled by the second mapping
means 222 wherein a mapping algorithm, which particularly is simpler than the one used in
the first mapping means, since the identity already was generated internally, maps it to a
load index. In this particular case it is supposed that iiy is mapped to load index LI24. Since
the internal identity was already generated internally in the server node, the load index can
easily be identified or extracted out of the internal identity. Using LIM 302 in interface
board 202, it can be seen that LI24 is handled by P4, and hence the message with the
internal identity iiy is sent to P4.
Further it is supposed that an incoming message MiZ is received in interface board 201. It is
here supposed that the client is not identified by the normal identity but with an identity
that is similar to an internal identity, and it will hence be handled in the second mapping
means 221 and mapped onto (here) LI12 which, using LIM 301 is established to be handled
by P2 102. The message with identity yz is sent to P2. However, yz was not really an
identity generated internally in the node but an identity of a similar type, for example a P-
TMSI. Later on P2 102 is made aware of the fact that the client identified through yz
15

actually has a normal identity NIDZ and then it is established which load index that identity
corresponds to or is mapped to and if it is not the same load index or another load index
handled by P2, the message or client is transferred to, in this case, P3 which is the
processing means that handles the load index which NIDZ is mapped to (which e.g. is
established in LIM 3012 in communication with a first mapping means).
The procedure of providing an internal identity as well as the procedure of allocating such
messages and a message with a normal identity will now be explained with reference to
Figs. 2 and 3 according to one embodiment.
As referred to above, according to the present invention it gets possible to distribute clients
or subscribers substantially evenly over in a server node available processing means in
such a way that incoming messages concerning a particular client can be routed to the
processor handling that client without having to maintain an explicit table mapping the
identity used in the incoming message to the processor, i.e. all identities to respective
processors. The routing adapts to the disappearing and appearing of processors. It should
be clear that, when discussing a server node here, the inventive concept is applicable to a
large variety or different kinds of server nodes and different systems etc. An example is on
3GPP (Third Generation Partnership Project) nodes, such as BSC, RNC, MSC, SGSN,
GGSN, CGSN, HLR, SCP as referred to above, but the concept is of course by no means
limited to 3GPP nodes.
Generally the inventive concept is based on the assumption that each client or subscriber
has a unique normal identity, NID. The type of the normal identity is actually determined
by the type of the server node, which here is expressed as "a for the server node normal
identity". In an SGSN, MSC or HLR, the normal identity will typically be the IMSI
(International Mobile Subscriber Identity) of a subscriber, whereas in an EIR (Equipment
Identity Register) it would be the IMEI associated with the equipment, whereas for other
types of nodes it might be the subscriber (MS) ISDN etc. It is further assumed that
spontaneous messages from an external network element (NE) regarding a particular client
or subscriber either are addressed using the normal identity of the client or the subscriber,
or they occur with a very low frequency, i.e. a manual addition of an intercept case, where
16

many different types of identities may be used, for example IMEI or (MS) ISDN etc.
depending on server node, which here makes a broadcast to all processors of a viable
addressing strategy. It should be clear that this merely relates to specific implementations
of the inventive concept and such messages, which are not addressed using the normal
identity, or spontaneous, from an external network element and which occur with a very
low frequency also can be handled in other manners; the inventive concept not being
limited to any specific way for handling such messages, although, in one implementation it
is indicated that they can be handled through using broadcast.
Still further another assumption is that non-spontaneous messages from an external
network element NE concerning a particular client or subscriber handled by the server
node always are preceded by the establishment of a connection between the server node
and the network element during which the server node provides the network element with
a reference identity for the particular client or subscriber. This reference identity may then
be used in all subsequent messaging from the external network element concerning the
client or included in an internal identity generated by the server node actually forming the
internal identity as discussed above and as also will be discussed more thoroughly below.
According to the invention, and with reference also to Fig. 1, it is supposed that a list or a
table or similar 31 is provided designating a range of load indices [0,..., n,] or as in Fig. 1,
1-36. To provide an optimal load balancing also when a processor disappears, n here
preferably is in the order of p , p here being the number of processors in a maximum
server node configuration. It should of course be clear that the number of load indices may
be somewhat lower as well as somewhat higher or even much higher.
Hence, the load index map (LIM) 30 maps load indices to processors particularly in such a
way that the load indices are evenly distributed over the processors. However, also other
distribution strategies are possible. As referred to above LIM is preferably maintained and
computed by a centralized object in the server node and distributed to each processor, and
also to each interface board. A further feature is that LIM is recomputed and redistributed
only when a processor appears or disappears (and possibly when an interface board
appears or disappears).
17

Particularly a designated normal identity mapping algorithm, in Fig. 3 denoted F can be
selected as a first mapping means for mapping normal identities to load indices. When
given a normal identity, the mapping algorithm F computes a load index. Preferably the
mapping algorithm used in the first mapping means is selected in such a way that it with a
high probability is capable to distribute any set of normal identities representative for a
real population of clients or subscribers, preferably evenly, over the range of load indices.
Any type of a simple Hash algorithm may for example be used. In one embodiment
F(N)=(NmodK), where K is the number of load indices.
In order to route an incoming message addressed using the normal identity, e.g. NID, to the
appropriate processor, F(N) is used to map the NID to a load index, and then LIM is used
to map the load index to a processor.
For each type T of identities that are provided by the server node as client references to
external nodes, i.e. for non-spontaneous messages form external network elements
concerning a particular subscriber or client as referred to above, in one embodiment cf.
Fig. 2, a designated identity server IST can be developed together with a T mapping
algorithm GT. Hence, for any given load index L, IST will generate a unique identity I of
type T, i.e. an IT, such that GT(IT)=L.
Hence, IST can be used to generate a reference identity here called IT, for a client or
subscriber C with normal identity NID N based on the load index F(N). Hence,
GT(IT)=F(N).
Thus, GT may be used for routing incoming messages addressed on identities of types T to
the correct processors.
IST may for example be realized by explicitly encoding, in each generated identity I, the
load index LI, and a unique sequence number S. By maintaining a list of all allocated
sequence numbers, a new unique identity may be generated from the next, non-allocated
18

sequence number. Further more GT is then simply implemented by extracting the explicitly
encoded load index.
This procedure is for example illustrated in Fig. 2 in which a message M[(IT1)] is
generated by identity server IS(T1) in a processing means P55 in a server node 501, which
message is sent to external network element NE 1 which responds with a message
M[I(T1)] containing the identity generated by the identity server. Correspondingly for a
message using an identity of type T2. It should be clear that the identity servers may be
implemented in many different ways but particularly in each processing means. They may
also be located in a centralized or partly distributed way in the server node.
Hence, Fig. 3 schematically illustrates an example of reception of different types of
messages while using a selected first or second mapping algorithm together with LIM to
map to the correct processor where the subscriber or client is handled. In this embodiment
processors P11-P15 are illustrated. Further a number of interface boards 201', 202', 203',
204' each handling different types of messages are disclosed. It is supposed that a message
with a normal identity, here illustrated as M(N), is incoming on interface board 203'. The
message is handled by a first mapping means 213' comprising a first mapping algorithm
F(N) and mapped to a load index LI which in the LIM 303' table is mapped to processor
P12. Hence message M(N) is routed to P12. It is also supposed that a response message
M{I(T2)} is incoming on interface board 202', mapped to a load index LI in second
mapping means 222' using a mapping algorithm for a type T2 messages, GT2(I(T2)). Then
it is established in LIM 302' that the particular, found load index is handled by processor
P14. Similarly, a response message M{I(T1)} incoming on interface board 2(V is handled
in second mapping means 212' using a mapping algorithm for type T1 and established in
LIM 301' to be handled by a processor P11.
Fig. 4 schematically illustrates a server node 502 comprising a number of processing
arrangements, here PA 1A-PK IK and a number of interface boards IBA 20A-IBN 20N.
For reasons of clarity the centrally computed and maintained LIM table is not illustrated in
the figure, reference is here made to Fig. 1. However, it is illustrated that replicas thereof
or LIM tables are contained in all processing means and in all interface boards. The
19

intention of Fig. 4 is to explain the procedure, when, according to one embodiment, a
message MSG M(N) using a normal identity for a client known to the server node 502 is
incoming to an arbitrary interface, here IB 20N, (I1). Since M(N) contains a normal
identity, it is handled by a first mapping algorithm F(N) in first mapping means 21N, as
explained above, which maps the identity to a load index, here LIm, (21). In communication
with the LIM table in IB 20N, it is established that LIm is handled by PK 1K and, here, the
first mapping means 21N sends the message to PK 1K where there already is a context for
handling the specific client with normal identity N and hence this context will handle
message M (31).
Fig. 5 is a figure similar to Fig. 4 for a case when a message M(N) is addressed using a
normal identity N, received in an arbitrary interface board, here IB N, for an external
network element NE for a client which is not known to the server node 502. In this figure
similar reference numerals are used as in Fig. 4. Again the first mapping algorithm F(N) is
used to map N to a load index, here found to be LIM. According to LIM, that load index
LIM maps to server processor PK 1K (22). Therefore the message N is forwarded to
processor PK 1K. In processor PK however there is no context for handling the client with
NID N and therefore a context is created, (32). The created context then handles the
message M(N).
Fig. 6 is a figure similar to Figs. 4 and 5 illustrating a server node 503 with a number of
processors, particularly control processors (as it can be in any one of the other
embodiments as well) PA-PS, each with a LIM, and a number of interface boards, here
IBA-IBQ 20A'-20Q' each with first mapping means 21A'-21Q', second mapping means
22A'-22Q' and a LIM. As in Fig. 4 and Fig. 5 the centrally computed LIM is not
illustrated in the figure. In the embodiment described with reference to Fig. 6, it is
supposed that a message M is addressed using an internal generated identity for a known
client. Hence, it is supposed that message M (IT) addressed on IT is received on an arbitrary
interface, here IBQ 20Q' from an external network element, (13). Since it is of type T, a
second mapping means 22Q' with a second mapping algorithm GT is used to map IT to a
load index, which here for example is supposed to be LI14 (23). According to LIM with
which the second mapping means 22Q' communicates, LI14 is mapped to the server
20

processor PC. Hence, the message M (IT) is forwarded to PC (33). In processor PC there is
a context for handling the client, since it was known, with identity IT and that context will
handle message M.
Fig. 7 again illustrates a server node 504 and an external network element NE. However,
in this case it is supposed that a dialogue is initiated by the server node 504. Here it is
supposed that the server node 504 comprises a number of processors PA-PR and a number
of interface boards IBA-IBL 20A"-20L". Hence, it is supposed that processor PR initiates a
dialogue with the external network NE regarding a certain client, (14), and an identity IT is
included in the initiating message. IT is constructed in such a way that subsequent
messages from the external NE can be correctly routed to the context of the client in PR.
This is achieved by e.g. inserting the load index of F(N) in IT or by other means encoding
F(N) in IT in such a way that it can be extracted from IT using an algorithm, wherein N is
the normal identity of the client. Then the message is handled in the first mapping means
21L", where a mapping performed between the established load index, here for example
LI25 and a processor PR having initiated the message that is handled by the first mapping
means in for example IBL 21L". The message is then sent to the external network element
including identity N2 and the external network element stores IT SO that it can be used as an
address in subsequent messages to the server node 504, regarding the particular client.
Fig. 8 shows a server node 505 comprising a number of processors P1-PK and a number of
interface boards IBA-IBL 20A'"-20L'" and an external network element NE. In this case it
is supposed that the initiating message from the external network element is not addressed
on NID. Instead a message M (IT) is received on, here, interface board IBL 20L"', (15).
Since it is not addressed using a normal identity, a second mapping means 22L"'
comprising an algorithm GT is used to map IT to a load index LI, here it is supposed that it
is mapped onto LI50 (25), and according to LIM, LI50 is mapped to processor PK. The
message is then sent to PK but there is no context for handling a client with the identity IT
in PK, therefore a context has to be created which subsequently will handle message M
(35). However, in this case it is supposed that the internal identity actually was not an
internally generated identity but just similar to that as to the type, and the client actually
has a normal identity, and during the processing of the initiating message the normal
21

identity N of the client is received from the network. If F(N), or the corresponding load
index is different from that handled by PK or any of the loading indices handled by PK, the
context and the handling of the message is transferred (45), here, to a context for example
in PA, which is established to be the right one.
Finally Fig. 9 is a schematical flow diagram describing a procedure according to the
inventive concept. However, the steps performed when a message is allocated on the
"wrong" processor, c.f. Fig. 8, are not included.
Hence, it is supposed that a message is received in an interface board of a server node (SN)
from an external NE, 100. It is established if the client is identified through an identity
which is normal for SN, 101. If yes, the mapping of the normal identity NID111x to a load
index is done for example using a Hash function in the first mapping means of the
receiving interface board, which mapping here is supposed to give the load index LI22,
102. Then the load index-to-processing means mapping table LIM provided on the
interface board is used to map between the load index, here LI22, and processor, giving
processor Pxy which hence is the processor handling the load index LI22, 103. Subsequently
the message is sent to Pxy, 104, in any appropriate manner, and Pxy creates or establishes
and sends a reference identity enabling recognition of the load index to the client and/or to
the external network element to enable routing of the same client to Pxy in subsequent
messaging, 105.
If however, it was established that the client was not identified through an identity which is
normal for SN, it is established whether the client is identified through an internal identity
e.g. generated internally in SN, 101 A. (It should be clear that the establishment as to
whether it is a normal identity or an internal or internally generated identity can be done
simultaneously, or in another order, this is merely a schematical example.) If not,
according to one implementation a broadcast can be sent to all processors in SN, 101B. If
however it was established that the client was identified through an internally generated
identity, a mapping of the internally generated identity to load index is performed in the
second mapping means in the receiving interface board, for example through extraction of
the relevant identity or reference identity, 102A. The load index to processor mapping
22

table LIM on the interface board is used to map between the found LI and processing
means, here supposed to give processor Pxz, 103A. The message is thereafter sent to Pxz,
104A, and Pxz creates or establishes a reference identity enabling the recognition of LI to
the client and all the external network elements to enable routing of the client to Pxz in
subsequent messaging, case 105A. In this case it is easy since the message already was
generated based on load index or a reference identity during previous generation for
example during a handshake procedure or during establishment of a connection etc.
It should be clear that the invention is not limited to the explicitly illustrated embodiments,
but that it can be varied in a number of ways, be implemented in different kinds of
systems, telecommunications systems, data communication systems and other systems
whenever a server node is handling a large number of subscribers and comprises a number
of processors and where an even or some other desired distribution of the load, for
example clients or subscribers, is needed, and also when there, at least not as a general
rule, is a question about single transactions.
23

WE CLAIM:
1. An arrangement adapted to be provided in a server node in a telecommunication or
data communication system, handling a large number of clients or subscribers, comprising
a number of interface boards handling one or more protocols for communication with
different nodes, node types and clients and a number of processing means adapted to serve
a plurality of clients or subscribers mostly for more than a single transaction and which
may use a number of different types of identities when addressing the server node,
characterized in
that it comprises at least partly distributed load distribution control means adapted to
handle clients or subscribers using at least two different categories of addressing identities
separately, and to appropriately distribute the clients or subscribers to processing means,
said load distribution control means being adapted to provide a number of load index
values, said number exceeding the number of processing means, and comprising load
index mapping means adapted to provide a mapping between load index values (LI1, LIII)
and processing means, and to represent the mapping in a load index mapping table (LIM),
and further being adapted to distribute such mapping tables or load index mapping table
replicas to substantially each interface board and each processing means, and comprising
first mapping means handling clients or subscribers using a first category of identity
comprising a for the server node normal identity e.g. generated externally of the
arrangement or the server node, said first mapping means comprising a mapping algorithm
adapted to establish a load index value (LII) for an incoming message using said first
category of identity, second mapping means comprising a second mapping algorithm for
mapping second category or internally generated identities to respective load index values
(Lin) such that a client or subscriber identified through a first normal identity or a second
e.g. internally generated identity is handled by the processing means mapped to the
corresponding, established load index value (LII, LIII).
2. An arrangement according to claim 1,
characterized in
24

that the load index mapping means are adapted to map load indices to processing means
according to given criterias.
3. An arrangement according to claim 1 or 2,
characterized in
that the load index mapping means are adapted to map load indices to processing means
such that a substantially even load distribution among the processing means is obtained.
4. An arrangement according to any one of claims 1 -3,
characterized in
that the number of load indices available for mapping to processing means comprises
substantially p2, or at least p2, p being the number of processing means in the server node
or considerably exceeds p.
5. An arrangement according to any one of the preceding claims,
characterized in
that the mapping table is updated, e.g. re-established or recomputed, when the number of
available processing means is changed, e.g. one or more processing means is added and/or
removed.
6. An arrangement according to any one of the preceding claims,
characterized in
that the first normal category of identities comprises subscriber IMSIs.
7. An arrangement according to any one of the preceding claims,
characterized in
that said second category of identities comprise, for identities of non-spontaneous
messages from external network elements, e.g. GGSNs, SCPs, MSs/UEs, SGSNs, MSCs,
RNCs etc. concerning a specific client/subscriber, internally in the distributed load
distribution control means generated identities.
25

8. An arrangement according to any one of the preceding claims,
characterized in
that it comprises, particularly in each processing means, internal identity generating means
for generating identities intended at least for incoming messages or connection
establishments using another, second, category of identity.
9. An arrangement according to any one of the preceding claims,
characterized in
that it is adapted to handle at least a third category of identities separately and/or
differently from said first and second categories of identities.
10. An arrangement according to any one of the preceding claims,
characterized in
that the load distribution control means comprises a centralized object for computing,
maintaining and distributing the load index mapping means (LIM), or the load index table.
11. An arrangement according to any one of the preceding claims,
characterized in
that the first mapping algorithm for mapping between a normal identity and a load index
comprises a Hash algorithm, e.g. based on a Modulo operation.
12. An arrangement according to any one of the preceding claims,
characterized in
that it is adapted to be provided in an SGSN, GGSN, a CGSN, a Web server, an RNC, an
MSC, an HLR, an IMS node, an EIR etc. or any server node handling many
clients/subscribers generally during more than one transaction.
13. An arrangement according to any one of the preceding claims,
characterized in
that it is adapted to transfer a client or subscriber for which an internal identity has been
generated based on e.g. a second category identity, e.g. P-TMSI, if the arrangement
26

subsequently receives information about the normal identity of the client/subscriber to the
processing arrangement handling the load index to which said normal identity is mapped.
14. An arrangement according to any one of the preceding claims,
characterized in
that if a client/subscriber has a normal identity and the arrangement gets knowledge about
the normal identity, it is adapted to always map the normal identity to a load index with the
first mapping algorithm.
15. An arrangement according to any one of the preceding claims,
characterized in
that substantially each interface board comprises a first mapping means and a second
mapping means.
16. An arrangement according to any one of the preceding claims,
characterized in
that each processing means comprises an internal identity generating means.
17. An arrangement according to any one of the preceding claims,
characterized in
that it is adapted to generate a reference identity based on the load index and/or through
which the load index can be extracted for each normal identity and for each second or
internally generated identity, and in that said reference identity is provided to the client or
subscriber such that a client or user always can be directed or handled by the same
processing arrangement in the server node.
18. An arrangement according to any one of the preceding claims,
characterized in
that the processing arrangements are integrated with processing boards.
27

19. A server node in a telecommunications system or a data communications system,
e.g. a GGSN, a CGSN, an HLR, an SGSN, an RNC, an MSC, a WEB server, an IMS node
etc,
characterized in
that it comprises an arrangement as in any one of claims 1-22.
20. A method for controlling the distribution of clients or subscribers communicating
with a server node comprising a plurality of processing means in e.g. a data
communications system or telecommunications system,
characterized in
that it comprises the steps of:
establishing whether a message received on an interface board is addressed using a
for the node normal identity specific for the subscriber or client,
if yes,
using an algorithm for mapping the normal identity to a load index in a first
mapping means in the interface board,
mapping the load index to a processing means using a mapping table provided in
the interface board, or
if it is addressed using an internal identity e.g. generated in the node,
mapping the internal identity to a load index in a second mapping means using an
algorithm,
mapping the load index to a processing means using the mapping table provided in
the interface board.
21. A method according to claim 20,
characterized in
that it comprises the step of:
providing or generating an internal identity for a subscriber or client establishing a
connection directly or indirectly over an external node over an interface board
using another type or second category of identity,
using an algorithm for mapping the internally generated identity to a load index in
a second mapping means,
28

mapping the load index to a processing means using the mapping table provided in
the interface board.
22. A method according to claim 20 or 21,
characterized in
that it comprises the step of:
29
using a reference identity based on the load index for the normal identity or the
internally generated identity for all subsequent communication concerning the
client or subscriber.

The present invention relates to an arrangement adapted to be provided in a server node
(50) in a communication system, handling a large number of clients, comprising a number of interface boards (201,202,203) handling one or more protocols for communication with different nodes and a number of processing means (101,...,106) adapted to serve a plurality
of clients which may use a number of different types of identities when addressing the
server node (500). It comprises load distribution control means adapted to handle clients using at least two different categories of addressing identities separately, and to distribute the clients to processing means (101,...,106), and being adapted to provide a number of load index values (LI1-LI36), exceeding the number of processing means, and load index mapping means mapping between load index values and processing means in a load index
mapping table (30,301,302,303,3011-3016). It is further adapted to distribute mapping tables
or to substantially each interface board (201,202,203) and each processing means
(101,...,106), and first mapping means comprising mapping algorithm (211,212,213)
handling clients or subscribers using a first category of identity comprising a for the server
node normal identity e.g. generated externally, said mapping algorithm being adapted to
establish a load index value (LI1) for an incoming message using said first category of
identity, and second mapping means (221,222,223) comprising a second mapping algorithm for mapping second category or internally generated identities to respective load index values such that a client will be handled by the processing means (101,...,106) mapped to the corresponding, established load index value.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=HXi+xON3RXUdUtajL9EHkQ==&loc=wDBSZCsAt7zoiVrqcFJsRw==

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Patent Number

269240

Indian Patent Application Number

258/KOLNP/2008

PG Journal Number

42/2015

Publication Date

16-Oct-2015

Grant Date

12-Oct-2015

Date of Filing

18-Jan-2008

Name of Patentee

TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

Applicant Address

SE-164 83 STOCKHOLM

Inventors:

#	Inventor's Name	Inventor's Address
1	BONNIER, STAFFAN	ASKIMS ÄNGSVÄG 13, S-436 40 ASKIM
2	FREDÉN, ANDERS	ASPLYCKEVÄGEN 13, S-429 31 KULLAVIK
3	WINELL, STAFFAN	GÅSMOSSEN 71, S-436 39 ASKIM
4	RÖNNEKE, HANS	KÅLLADSGÅRDSGATAN 18, S-434 36 KUNGSBACKA

PCT International Classification Number

H04L 29/06

PCT International Application Number

PCT/EP2005/006813

PCT International Filing date

2005-06-23

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA