SYSTEM, NETWORK ENTITIES AND COMPUTER PROGRAMS FOR CONFIGURATION MANAGEMENT OF A DYNAMIC HOST CONFIGURA¬ TION PROTOCOL FRAMEWORK

BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION

The present invention relates to packet data networks. In particular, the present invention re- lates to a novel and improved system, and network en¬ tities for configuration management of a dynamic host configuration protocol framework comprising at least one DHCP server, at least one configuration storage and at least one storage manager and at least one net- work server, wherein a configuration storage is con¬ nected to at least one DHCP server, a configuration storage is connected to at least one DHCP server and a storage manager is connected to at least one configu¬ ration storage and to at least one network server.

DESCRIPTION OF THE RELATED ART The DHCP (Dynamic Host Configuration Proto¬ col) is a communication protocol that lets network ad¬ ministrators manage centrally and automate the assign¬ ment of Internet Protocol (IP) addresses e.g. in an organization's network. Using the Internet Protocol, each machine that can connect to the Internet needs a unique IP address. When an organization sets up its computer users with a connection to the Internet, an IP address must be assigned to each machine. Without the DHCP, in IPv4 the IP address must be entered manu- ally in each computer and, if computers move to an¬ other location in another part of the network, a new IP address must be entered. IPv6 provides a stateless address autoconfiguration functionality (Neighborhood Discovery protocol, ND) that can replace the address assignment functionality of the DHCPv6. In other words, in the IPv6, manual address configuration is not the only option if the DHCPv6 is not used. The DHCPv6 is an example of a statefull address autocon- figuration method for the IPv6. Furthermore, some proprietary method can also be used to configure IP addresses. The DHCP lets a network administrator super- vise and distribute IP addresses from a central point and automatically sends a new IP address when a com¬ puter is plugged into a different place in the net¬ work. This is always done in a solicited manner, that is, a computer must explicitly request the network to assign a new address for it. DHCP server configuration management is typi¬ cally based on manual configuration of a configuration file, which easily can lead to outdated information being provided to the DHCP clients. Figure 1 de- scribes a typical prior art solution. A Dynamic Host Configuration Protocol (DHCP) server 10 includes a configuration file 12. Configuration file 12 includes configuration parameters, e.g. assignable IP ad¬ dresses, so that DHCP server 10 is able to provide services to terminal devices. A user may edit con¬ figuration file 12 via a user interface 14. The configuration file is interpreted by server process in its initializing phase (start/restart) . Each time when a change is needed in the server configuration the configuration file or other data storage is manually edited, and to make the changes apply in server process, required procedures are executed, e.g. by restarting the server process. Manual configuration involves (human) admin- istrator interaction and there is always a possibility of a human error when maintaining manually configura- tion data. Moreover, it may be a time consuming task and it is not suitable for delivering configuration parameters that have a short lifetime or require fre¬ quent updates. Automated or semi-automated generation of configuration parameters may be supported in a net¬ work server to decrease extra burden of manual con¬ figuration. Delivering configuration data to the end-user equipment from a network, in a user-friendly manner, is nowadays a problem especially for the mobile termi¬ nal vendors. In the future, when the networks are mo¬ bile (moving networks) , this problem becomes even big¬ ger. If a network operator has contracts with mul- tiple service and content providers as well as with multiple terminal vendors, there is no generic way in which all those parties may dynamically provide re¬ quired configuration data for the use of the operator. This has to be done because the operator owns presuma- bly the configuration framework of its network like DHCP framework. Based on the above, there is an obvious need for a solution that would improve DHCP framework con¬ figuration management.

SUMMARY OF THE INVENTION According to one aspect of the invention there is provided a system for configuration manage¬ ment of a dynamic host configuration protocol frame¬ work, the system comprising a dynamic host control protocol server, a configuration storage, a storage manager and a network server. The configuration stor¬ age is connected to the dynamic host control protocol server and is configured to store configuration pa¬ rameters to be used by the dynamic host control proto¬ col server. The storage manager is connected to the configuration storage and to the network server and is configured to maintain content in the configuration storage and manage signaling and data transfer between the configuration storage and the network server. The network server is connected to the storage manager and is configured to provide the storage manager with the configuration parameters. Furthermore, the storage manager dynamically updates configuration data in the configuration storage. In one embodiment of the invention, the stor¬ age manager is configured to remove expired configura¬ tion data content from the configuration storage. In one embodiment of the invention, the stor¬ age manager is configured to monitor configuration data content in the configuration storage and to re¬ quest updated configuration data content from the net¬ work server; and the network server is configured to provide the storage manager with updated configuration data in response to receiving a request for the up- dated configuration data content from the storage man¬ ager if the updated configuration data is available. In one embodiment of the invention, the con¬ figuration storage is configured to trigger a configu¬ ration data content request to the one storage manager if applicable configuration data does not exist in the configuration storage, the storage manager is config¬ ured to trigger the configuration data request to at least one network server, the at least one network server is configured to provide the storage manager with the applicable configuration data in response to the configuration data request if the applicable con¬ figuration data is available, and the storage manager is configured to provide the configuration storage with the applicable configuration data in response to the configuration data content request if the applica¬ ble configuration data is available. In one embodiment of the invention, the stor¬ age manager is configured to trigger the configuration data content request to the network server, and the network server is configured to provide the storage manager with the applicable configuration data in re¬ sponse to the configuration data content request if the applicable configuration data is available. In one embodiment of the invention, the network server checks whether the storage manager is allowed to receive the applicable configuration data, wherein the network server is configured to provide the storage manager with the applicable configuration data only if the storage manager is allowed to receive the applicable configuration data. In one embodiment of the invention, the stor¬ age manager is configured to trigger a configuration data content request to the at least one network server based on at least one of the following rules: the configuration storage sent the configuration data content request for non-existent configuration data to the storage manager, the configuration data in the configuration storage is about to expire and an up¬ dated piece of configuration data is needed, or expir¬ ing configuration data is marked as essential in the configuration storage. In one embodiment of the invention, the net¬ work server is configured to send updated configura¬ tion data to the storage manager automatically. In an¬ other embodiment, the network server is configured to send the updated configuration data to the storage manager automatically before the configuration data in the configuration storage expires. In one embodiment of the invention, the con¬ figuration storage is configured to include terminal device location dependant configuration data, the con¬ figuration storage is configured to receive a location dependent configuration data request from at least one dynamic host control protocol server, and the configu¬ ration storage is configured to provide the at least one dynamic host control protocol server with a loca- tion dependent configuration data in response to the location dependent configuration data request. In one embodiment of the invention, the net¬ work server and the storage manager are configured to establish a relationship between each other in order to exchange information. In one embodiment of the in¬ vention, the network server is configured to use pre¬ existing relationship between the network server and the storage manager in order to exchange information. In one embodiment of the invention, each service entry in the configuration storage comprises at least one of the following: a unique service iden¬ tifier identifying a service, the configuration data, and a time-to-live value for the configuration data. In one embodiment of the invention, a single entity comprises the dynamic host control protocol server, the configuration storage, the storage manager and the network server. In one embodiment of the invention, the sys¬ tem comprises at least one of the following configura- tions : a configuration storage is connected to at least one dynamic host control protocol server and to at least one storage manager; a storage manager is connected to at least one configuration storage and to at least one network server; and a network server is connected to at least one storage manager. According to another aspect of the invention there is provided storage manager for configuration management of a dynamic host configuration protocol framework, wherein the storage manager is connected to the configuration storage and the network server, wherein the storage manager is configured to maintain content in a configuration storage, manage signaling and data transfer between the configuration storage and a network server and dynamically update configura¬ tion data in the configuration storage. In one embodiment of the invention, the stor¬ age manager is configured to remove expired configura¬ tion data content from the configuration storage. In one embodiment of the invention, the stor¬ age manager is configured to monitor configuration data content in the configuration storage, to request updated configuration data content from the network server and to receive updated configuration data from the network server if the updated configuration data is available. In one embodiment of the invention, the stor¬ age manager is configured to receive a configuration data content request from the configuration storage and to provide the configuration storage with the con¬ figuration data in response to the configuration data content request if the configuration data is avail¬ able, and storage manager is configured to trigger the configuration data request to at least one network server and to receive the applicable configuration data from the at least one network server if the ap- plicable configuration data is available. In one embodiment of the invention, the stor¬ age manager is configured to trigger the configuration data content request to the network server based on at least one of the following rules: the configuration storage sent to the storage manager the configuration data content request for non-existent configuration data, the configuration data in the configuration storage is about to expire and an updated piece of configuration data is needed, or expiring configura- tion data is marked as essential in the configuration storage. In one embodiment of the invention, the stor¬ age manager is configured to establish a relationship between the network server and the storage manager in order to exchange information. In one embodiment of the invention, the network server is configured to use pre-existing relationship between the network server and the storage manager in order to exchange informa¬ tion. In one embodiment of the invention, the stor- age manager is implemented in an entity with at least one of a dynamic host control protocol server and the configuration storage. According to another aspect of the invention there is provided a configuration storage for configu- ration management of a dynamic host configuration pro- tocol framework, wherein the configuration storage is connected to a dynamic host control protocol server and to a storage manager, wherein the configuration storage is configured to store configuration parame- ters used by the dynamic host control protocol server; wherein the configuration storage is configured to be dynamically maintained and updated by a storage man¬ ager, and deliver configuration parameters to the dy¬ namic host control protocol server by a dynamic host control protocol server request and to send a configu¬ ration data content request to the storage manager if applicable configuration data does not exist in the configuration storage or if the applicable configura¬ tion data has expired in the configuration storage. In one embodiment of the invention, the con¬ figuration storage is configured to include terminal device location dependant configuration data, the con¬ figuration storage is configured to receive a location dependent configuration data request from at least one dynamic host control protocol server, and the configu¬ ration storage is configured to provide the at least one dynamic host control protocol server with a loca¬ tion dependent configuration data in response to the location dependent configuration data request. In one embodiment of the invention, the con- figuration storage is configured to receive a location dependent configuration data content request from the dynamic host control protocol server, and the configu¬ ration storage is configured to provide the dynamic host control protocol server with a location dependent configuration data in response to the location depend¬ ent configuration data content request. In one embodiment of the invention, each service entry in the configuration storage comprises at least one of the following: a unique service iden- tifier identifying a service, the configuration data, and a time-to-live value for the configuration data. In one embodiment of the invention, the con¬ figuration storage is implemented in an entity with at least one of the dynamic host control protocol server and the storage manager. In one embodiment of the invention, the con¬ figuration storage is connected to at least one dy¬ namic host control protocol server and to at least one storage manager. According to another aspect of the invention there is provided a computer program embodied on a computer readable medium for configuration management of a dynamic host configuration protocol framework, wherein the computer program controls a data- processing device to perform the steps of: maintaining content in a configuration storage and managing sig¬ naling and data transfer between the configuration storage and a network server, and updating configura¬ tion data in the configuration storage dynamically. According to another aspect of the invention there is provided a computer program embodied on a computer readable medium for configuration management of a dynamic host configuration protocol framework, wherein the computer program controls a data- processing device to perform the steps of : storing configuration parameters used by a dynamic host con¬ trol protocol server, delivering the configuration pa¬ rameters to the dynamic host control protocol server, receiving configuration data content maintenance op¬ erations from a storage manager, and generating a con- figuration data content request to the storage manager if applicable configuration data does not exist or if the applicable configuration data has expired. According to another aspect of the invention there is provided a network server for configuration management of a dynamic host configuration protocol framework, wherein the network server is connected to at least one storage manager, wherein the network server is configured to establish a relationship with a storage manager in order to exchange information, connect to at least one information storage comprising configuration data for a configuration storage and transmit the configuration data to the storage man¬ ager. In one embodiment of the invention, the net- work server is further configured to receive configu¬ ration data content requests from the storage manager. In one embodiment of the invention, the net¬ work server is further configured to check whether the storage manager is allowed to receive the configura- tion data, wherein the network server is configured to provide the storage manager with the configuration data only if the storage manager is allowed to receive the configuration data. In one embodiment of the invention, the net- work server is further configured to automatically transmit unsolicited modified or new configuration data to the storage manager. In one embodiment of the invention, the net¬ work server is further configured to transmit, based on an external trigger, unsolicited, modified, or new configuration data advertisements to the storage man¬ ager. In one embodiment of the invention, the net¬ work server is further configured to periodically transmit unsolicited configuration data advertisements to the storage manager. In one embodiment of the invention, the net¬ work server is further configured to transmit, based on an external trigger, at least a subset of the con- figuration data to the storage manager. In one embodiment of the invention, the net¬ work server is further configured to receive the con¬ figuration data from at least one external entity. In one embodiment of the invention, the net- work server is further configured to receive manage¬ ment data from at least one external entity. According to another aspect of the invention there is provided a computer program embodied on a computer readable medium for configuration management of a dynamic host configuration protocol framework, wherein the computer program controls a data- processing device to perform the following steps of : establishing a relationship between a network server and a storage manager in order to exchange informa- tion, connecting to at least one information storage comprising configuration data for a configuration storage, and transmitting the configuration data to the storage manager. According to another aspect of the invention there is provided a system for configuration manage¬ ment of a dynamic host configuration protocol frame- work, the system comprising a dynamic host control protocol server, a configuration storage connected to the dynamic host control protocol server, a storage manager connected to the configuration storage, a net- work server connected to the storage manager, storing means for storing configuration parameters used by the dynamic host control protocol server in the configura¬ tion storage, maintaining means for maintaining con¬ tent in the configuration storage and managing signal- ing and data transfer between the configuration stor¬ age and the network server with the storage manager, providing means for providing the storage manager with the configuration parameters with the network server, and updating means for updating configuration data in the configuration storage dynamically by the storage manager. According to another aspect of the invention there is provided a method for configuration manage¬ ment of a dynamic host configuration protocol frame- work, the method comprising maintaining content in a configuration storage and managing signaling and data transfer between the configuration storage and a net¬ work server, and updating configuration data in the configuration storage dynamically. According to another aspect of the invention there is provided a system for configuration manage¬ ment of a dynamic host configuration protocol frame¬ work, the system comprising maintaining means for maintaining content in a configuration storage, manag- ing means for managing signaling and data transfer be¬ tween the configuration storage and a network server, and updating means for updating configuration data in the configuration storage dynamically. According to another aspect of the invention there is provided a method for configuration manage¬ ment of a dynamic host configuration protocol frame- work, the method comprising storing configuration pa¬ rameters used by a dynamic host control protocol server, delivering the configuration parameters to the dynamic host control protocol server, receiving con- figuration data content maintenance operations from a storage manager, and generating a configuration data content request to the storage manager if applicable configuration data does not exist or if the applicable configuration data has expired. According to another aspect of the invention there is provided a system for configuration manage¬ ment of a dynamic host configuration protocol . frame¬ work, the system comprising storing means for storing configuration parameters by a dynamic host control protocol server, delivering means for delivering the configuration parameters to the dynamic host control protocol server, receiving means for receiving con¬ figuration data content maintenance operations from a storage manager, and generating means for generating a configuration data content request to the storage man¬ ager if applicable configuration data does not exist or if the applicable configuration data has expired. According to another aspect of the invention there is provided a method for configuration manage- ment of a dynamic host configuration protocol frame¬ work, the method comprising establishing a relation¬ ship between a network server and a storage manager in order to exchange information, having connectivity to at least one information storage comprising configura- tion data for a configuration storage, and transmit¬ ting the configuration data to the storage manager. According to another aspect of the invention there is provided a system for configuration manage¬ ment of a dynamic host configuration protocol frame- work, the system comprising establishing means for es¬ tablishing a relationship between a network server and a storage manager in order to exchange information, connecting means for connecting to at least one infor¬ mation storage comprising configuration data for a configuration storage, and transmitting means for transmitting the configuration data to the storage manager. The invention has several advantages over the prior-art solutions. The invention enables automatic delivery of any network configuration parameter from a network to a DHCP server or DHCP servers. Together with the standard DHCP protocol functionalities the invention provides auto-configuration of configuration parameters from network servers to hosts, e.g. to mo¬ bile terminals. Furthermore, the invention enables "more com¬ plete" auto-configuration of a host in a sense that if a configuration storage cannot provide the requested configuration information, the configuration storage tries to retrieve the configuration information from a network so that further requests for those missing pieces of configuration information would be success¬ ful. Furthermore, the invention enables location sensitive IP address and network configuration parame- ter resolving using the DHCP protocol.

BRIEF DESCRIPTION OF THE DRAWINGS: The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this specification, illus¬ trate embodiments of the invention and together with the description help to explain the principles of the invention. In the drawings: Figure 1 is a block diagram illustrating a prior art DHCP server configuration, Figure 2 is a block diagram illustrating a system according to the invention, Figure 3 is a block diagram illustrating an¬ other system according to the invention, Figure 4 is a block diagram illustrating an¬ other system according to the invention, Figure 5 is a block diagram illustrating an¬ other system according to the invention, Figure 6 is a block diagram illustrating a data communication network in which the invention may be used, Figure 7 is a block diagram illustrating dif¬ ferent geographical areas and a set of parameters cor¬ responding to the areas according to the invention; and Figure 8 is a block diagram illustrating an embodiment of a structure of a configuration storage or a storage manager.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Figures 2-5 disclose different embodiments of the invention. Since the basic functionality is the same in all of them, the figures will be described all together. DHCP protocols, defined in RFCs (RFC, Request for Comments) RFC 1541 and 3315 can be used to deliver network configuration parameters like a Domain Name System (DNS) server address list from a DHCP server to a DHCP client by the client's explicit request, or the server can add it automatically to any reply, if con¬ figured to do so. The invention at hand introduces a method, system, network nodes and computer programs that to- gether with the standard DHCP functionality mentioned above enable an auto-configuration framework that can be used to deliver any configuration parameters from network servers to hosts, e.g. to a mobile terminal. The system comprises three important entities in addition to a DHCP server 20. DHCP server 20 is connected to a dynamically updated configuration stor¬ age 22. The purpose of configuration storage 22 in the system is to store configuration parameters like DNS, mail, Session Initiation Protocol (SIP) or basically whatever service dependent or independent parameters that are required in a terminal device to enable that specific service or application. A simple format of a configuration parameter one can think of is an Inter- net Protocol (IP) address or Uniform Resource Locator (URL) address of a server providing a particular serv¬ ice. The main task of configuration storage 22 is to deliver requested configuration parameters to DHCP server 20 by server's request. In the configuration storage 22, each service entry contains all or some of the following pieces of network server specific information: Unique service identifier identifying the service in global scope. For example, a globally unique Internet Assigned Numbers Authority (IANA) vendor ID and vendor specific unique service ID. Configuration data represented either in a service specific or service independent format in such way that both the client and server application have the same interpretation of the data. - Time-to-live (TTL) value for the configuration data. Configuration storage 22 may also maintain its data consistency by taking care of data read/write locking etc. like a conventional database system. In another embodiment, storage manager 24 is responsible for maintaining data consistency in configuration storage 22. Configuration storage 22 also generates a specific event to storage manager 24, if some of the requested configurations are not available or have ex- pired in configuration storage 22, so that storage manager 24 may perform some actions, for example, to generate a solicitation message to network server 26. Configuration storage 22 may also have access control functions, that is, functions relating to which storage managers are allowed to provide configu¬ ration data to configuration storage 22. The configuration data along with the service identifiers are stored in configuration storage 22 as they are received from network server 26. The stored configuration data and the service identifier identi¬ fying it typically are application/service specific. Service identifiers, which can be compared to the option types in the standard DHCP protocol, are also the way for a terminal's applications to notify the DHCP server which configuration data they are re¬ quiring. Therefore, service identifiers are used as search keys in queries from the DHCP server to con¬ figuration storage 22. It is always possible that storage manager 24 is not able to provide configuration storage 22 with the requested configuration data. This may happen since a terminal requesting configuration parameters from DHCP server 20 in practice is free to ask any¬ thing in the framework and any request resulting no data in configuration storage 22 can trigger storage manager 24 to request missing data from network server 26. It is also possible that storage manager 24 does not provide configuration storage 22 or network server 26 does not provide storage manager 24 with the re¬ quested configuration data due to some rule or policy. The system further comprises a management en¬ tity that manages configuration storage 22, herein re¬ ferred to as a storage manager 24. Storage manager 24 is connected to configuration storage 22 and a network server 26. Storage manager 24 may be responsible for at least of the following functionalities: Managing the signaling and data transfer between configuration storage 22 and network server 26. Maintaining the data in configuration storage 22. In other words, as default e.g. removing of expired service entries and optionally requesting from network server 26 updated configuration data. One feature of storage manager 24 is to pro¬ vide a set of different methods for network server 26 to transfer its configurations to configuration stor¬ age 22. Any viable methods to transfer data between two nodes can be used depending on the requirements like security, reliability, etc. Storage manager 24 may offer a method or methods that can be used by new servers to create re¬ quired trust relationship to be able to join the dy- namic configuration system. Furthermore, there may be a trust relationship between the storage manager 24 and network servers, and therefore it may be limited which network servers may dynamically access configu¬ ration data via the storage manager. This may also mean that different services from trusted servers can join and leave the system at any time. In one embodi¬ ment of the invention, network server 26 may use pre¬ existing trust between network server 26 and storage manager 24 in order to exchange information. The trust may be established dynamically between storage manager 24 and network server 26 or alternatively, storage manager 24 and network server 26 may be preconfigured to have the trust. Furthermore, when a network server receives a configuration data request from a storage manager, the network server may determine whether it is allowed to process the request from the storage manager, and fur- ther, to determine whether the request concerns con¬ figuration data that the storage manager has a right to use. Correspondingly, the storage manager may check the integrity of the data received from the network server and the data origin authentication. A similar functionality may be configured to the interface between a storage manager and configura¬ tion storage. When the storage manager receives a con¬ figuration data request from the configuration stor¬ age, the storage manager may determine whether it is allowed to process the request from the configuration storage, and further, to determine whether the request concerns configuration data that the .configuration storage has a right to use. Correspondingly, the con¬ figuration storage may check the integrity of the data received from the storage manager and the data origin authentication. In one embodiment of the invention, storage manager 24 may use pre-existing trust between configu¬ ration storage 22 and storage manager 24 in order to exchange information. The trust may be established dy¬ namically between storage manager 24 and configuration storage 22 or alternatively, storage manager 24 and configuration storage 22 may be preconfigured to have the trust. In one embodiment of Figure 2, storage man¬ ager 24 is configured to trigger a configuration data content request to network server 26 based on at least one of the following rules: configuration storage 22 sent to storage manager 24 a configuration data con¬ tent request for non-existent configuration data, con- figuration data in configuration storage 22 will ex¬ pire and an updated piece of configuration data is needed, or expiring configuration data is marked as 'essential' in configuration storage 22. The system further comprises an additional entity in network server 26 that may have at least one of the following functionalities in the system: - Basic data transfer methods including supported protocol signaling, the local data management systems, etc. The server listens solicitations from storage manager 24 and sends updates according to them, if needed. To automatically update distributed data in configuration storage 22 before it expires. To periodically send unsolicited configuration data advertisements to configuration storages via storage manager 24. Advertised configuration data may refer e.g. to all configuration data or to changed configuration data. To automatically send unsolicited modified or new configuration data advertisements to configuration storages via storage manager 24. Based on external trigger(s) send unsolicited modified or new configuration- data advertisements to configuration storages. The data may not be sent until some entity (e.g. human, internal or external computer program) triggers the sending. Network server 26 comprises also a configura¬ tion database for storing configuration parameters, or alternatively or additionally, it may have been con¬ nected to an external database. Network server 26 or some other entity may maintain the configuration data in the database automatically or semi-automatically. Network server 26 may also have an interface to at least one external entity from which it receives con¬ figuration data on request or in an unsolicited man- ner. Network server 26 may have another interface to at least one external entity from which it receives management data. The management data refers e.g. to data based on.which network server 26 sends configura¬ tion data advertisements to storage manager 24 etc. When network server 26 receives configuration data requests from storage manager 24, it may send the request further to a predetermined external entity as described above. If network server 26 receives from storage manager 24 a configuration data request that cannot be replied to, it may generate an event e.g. to a log file. The event may indicate where the request came from, to which DHCP server it relates to and what was the missing configuration data etc. It is obvious that at least one of network server 26 and storage manager 24 may refer to a physi¬ cal device implementing functions described above or alternatively to a server process running in a com¬ puter. Messaging between storage manager 24 and net- work server 26 can be either unsolicited, i.e. network server 26 is pushing configuration to storage manager 24. Alternatively, as mentioned under specific circum¬ stances storage manager 24 can generate a solicitation for specific configuration to network server 26. Both storage manager 24 and network server 26 can be responsible for maintaining the content in con¬ figuration storage 22: - Storage manager 24 removes expired content from configuration storage 22. Storage manager 24 may also monitor the content in configuration storage 22 and notify network server 26 about expiring content. - Network server 26 can, independently of management notification(s) , maintain the data in configuration storage 22 it has access to via storage manager 24, or alternatively, it can listen management notifications from storage manager 24 and act according to them when needed. In Figure 2, network server 26 may be con- nected to a plurality of storage managers. Therefore, network server 26 may transfer configuration(s) to a plurality of storage managers. In another embodiment, network server 26 may receive notifications from mul¬ tiple storage managers 22. Yet in another embodiment, storage manager 24 may manage multiple configuration storages 22. Yet in another embodiment, storage man¬ ager 24 may receive solicitation triggers from multi¬ ple configuration storages 22. Yet in another embodi¬ ment, configuration storage 22 may receive queries from multiple DHCP servers, but in some implementation cases one database per DHCP server is a suitable con¬ figuration. The invention at hand may be implemented in various ways. In the following some of the possible implementation alternatives are disclosed. Architectural alternatives, system entity re¬ lations and system scalability and complexity are de¬ pendent on how configuration storage, configuration storage manager and DHCP server are implemented into the system. In Figures 3-5 a rectangle or a polyhedron surrounding certain system entities represents sepa- rate implementation module where external signaling is not needed. These module (s), however, are transparent to the hardware configurations, e.g. the modules can be in the same hardware node, or each module can have a separate node. If configuration storage 32, storage manager 34 and DHCP server 30 are implemented into the same module (Figure 3, 38), the system entity scalability is simple. In other words, one storage manager only manages one configuration storage, and the DHCP server can have only connected storage. However, multiple network servers 36 can transfer their configuration data to multiple managers. If only the configuration storage 42 is im¬ plemented in the same module with DHCP server 40 (Fig- ure 4, 48) , storage manager 44 becomes more scalable and can be used to manage several configuration stor¬ ages. Again, multiple network servers 46 can transfer their configuration data to multiple managers. A third alternative is to have configuration storage 52 and storage manager 54 implemented into the same module (Figure 5, 58) . This architecture corre¬ sponds to the first one (Figure 3) , with the exception that the same configuration storage can serve multiple DHCP servers and DHCP server 50 may use several dif- ferent storages for its queries. Again, multiple net¬ work servers 56 can transfer their configuration data to multiple managers. A fourth alternative was represented in Fig¬ ure 2 where all three entities are implemented in dif- ferent modules. This architecture provides the highest scalability for system entities, but also the entity functionalities become more complex than in other al¬ ternatives, because relations between system entities are all many to many and this requires extra manage¬ ment in each system entity. The special case where all system entities are in the same module is another implementation al¬ ternative. In this special case all relations between entities are one-to-one. An example of such a system could be a configuration where a large database is representing a network server entity. It is obvious, based on Figures 2-5, that a DHCP server, configura¬ tion storage, storage manager and network server may be implemented within a single entity or that each node may be implemented in separate entities. Further- more, it is also obvious that any other implementation alternative between the aforementioned implementations is possible. Referring to Figure 2, it is evident that re¬ lationships between adjacent network elements (i.e. 20-22, 22-24 and 24-26) may be one-to-one or one-to- many. In the future when networks are becoming mo¬ bile and more heterogeneous, it may be assumed that these networks are representing potential new users of auto-configuration frameworks. In the heterogeneous environment like this, the nature of the required con¬ figuration data can vary a lot depending on factors such as type of users (terminal/network) , type of ter¬ minal and type of network. Figure 6 discloses an overall system view of a data communication network in which the invention may be applied. Figure 6 discloses four Dynamic Host Configuration Protocol (DHCP) frameworks 60, 62, 64 and 66 that are interconnected with each other via routers 68, 606 and 664. The system includes a set of DHCP servers 644, 672 each being connected to at least one configuration storage 602, 624, 660. For example, DHCP server 644 is connected to two configuration storages 624 and 602. Figure 6 presumes that a storage manager dis- closed in Figures 2-5 is implemented together with a respective configuration storage. The system further comprises a plurality of network servers 600, 604, 622, 628, 630, 662 connected to at least one configu¬ ration storage. For example, network server 604 is connected to configuration storages 602 and 660 di¬ rectly of via a router 606 or routers 606, 664. Terminal devices, e.g. mobile terminals 674, 642, 668 and 670, are connected to a DHCP server via an access router 640 or 666. If DHCP servers are used also by mobile ter¬ minals, configuration storages may be provided also e.g. with location, device model or device manufac¬ turer specific configuration data. For example, mobile terminal's 668 address may be provided to DHCP server 672. In other words, the invention defines location sensitive DHCP configuration, implementation that of¬ fers mobile terminals' location info as a part of DHCP auto-configuration phase for the DHCP server usage. In one embodiment, location information of a mobile terminal may be added by the originating node (e.g. DHCPv6 client in the mobile terminal) or DHCPv6 Relay Agent or some other entity on the signaling path before the DHCP server. This implementation is not network architecture dependant. In other words, it can be applied to the 3rd generation mobile networks as well as ad-hoc networks. In another embodiment some proprietary method may be used by the DHCP server to request mobile ter¬ minal's location information based on its identity. This implementation may not be so generic as the pre- vious one, but it would more secure and mobile termi¬ nal's privacy would be easier to maintain. Either one of the previous embodiments can be used, for example, for the following purposes: Load sharing among DHCP servers. - Location based address allocation. Location based network parameter configuration. Location information of a mobile terminal can be used, e.g. in large mobile networks, to do load sharing among DHCP servers so that DHCP Relay Agent decides to which DHCP server mobile terminal's DHCPvδ message is forwarded based on the location informa- tion. If the Relay Agent does not have this kind of information available, then it may forward the DHCP message normally toward DHCP server(s) .' And when the DHCP server receives the mobile terminal originated DHCP message, it either ignores or processes it based on the location information delivered via the message. If the DHCP server decides to process the received DHCP message, it may choose a correct set of parame¬ ters in the configuration storage or it may use a cor¬ rect scheme of address allocation based on the loca- tion information. In another embodiment the mobile terminal's identity information is delivered with a DHCP message and then the DHCP server could request mobile terminal's location information based on the delivered identity. Figure 7 describes one embodiment including three different areas (Area 1, Area 2 and Area 3) and corresponding area-specific set of parameters (Set of parameters 1, Set of parameters 2 and Set of parame¬ ters 3) . Mobile terminals are roaming around in the three areas and they might request some network con¬ figuration parameters using the DHCP protocol and the same DHCP framework. In other words, there are no area-specific DHCP frameworks. Based on mobile termi¬ nals' location information, a correct set of parame¬ ters can be delivered to them. Depending on the security requirements, some type of encryption might be needed for the location information while transferring it via an IP packet be¬ cause of privacy reasons. Furthermore, the mobile ter¬ minal's location information may be acquired in any appropriate way and by any appropriate network entity. When implementing localized services in mo¬ bile or data networks, that is, services that are available only in certain part of a network and that are beneficial to a user only if the user is in a spe¬ cific (geographical) area, it evidently becomes a problem for both the network and mobile terminal, how to keep track on what services are available in the specific network area and how this information can be made available in the mobile terminal. Figure 8 is a block diagram illustrating an embodiment of a structure of a configuration storage or a storage manager. In this embodiment, the struc¬ ture disclosed in Figure 8 may be applied both to a configuration storage and a storage manager. The con¬ figuration storage and storage manager are herein re- ferred to as a network node 88. Network node 88 comprises at least a central processing unit (CPU) 82. Furthermore, network node 88 comprises a receiver 80, a transmitter 84 and a memory 86 that are connected to CPU 82. If network node 88 is a configuration stor¬ age, receiver 80 is configured to receive configura¬ tion parameter requests from a dynamic host configura¬ tion protocol (DHCP) server and to receive configura¬ tion data from a storage manager. Furthermore, trans- mitter 84 is configured to transmit configuration data requests to at least one storage manager and to trans- mit configuration parameters to at least one DHCP server. Memory 86 is configured to store configuration parameters to be used by at least one DHCP server. If network node 88 is a storage manager, re- ceiver 80 is configured to receive configuration pa¬ rameter requests from at least one configuration stor¬ age and to receive configuration data from at least one network server. Furthermore, transmitter 84 is configured to transmit configuration data requests to at least one network server and to transmit received configuration data to at least one configuration stor¬ age. Figure 8 illustrates only a single memory 86 in network node 88. Memory 86 may refer to a single memory or memory area or to a plurality of memories or memory areas that may include e.g. random access memo¬ ries (RAM) , read-only memories (ROM) etc. Memory 86 may also include other applications or software compo¬ nents that are not described in more detail and also may include the computer program (or portion thereof) , which when executed on the CPU 82 performs at least some of the method steps of the invention. CPU 82 may also include a memory or a memory may be associated therewith which may include the computer program (or portion thereof) which when executed on CPU 82 per¬ forms at least some of the method steps of the inven¬ tion. The invention enables provisioning of con¬ figuration parameters to mobile terminals according to their locations. These parameters may include e.g. an URL or other addressing information of a management server or other entity, which contains localized serv¬ ice information of a certain network area. When a mo¬ bile terminal adds its current location information to a DHCP message, to reply the DHCP server can automati¬ cally add the requested URL based on what services specific to the mobile terminal's location are made available. The location-specific information may be arranged to the DHCP server as was described in Fig¬ ures 2-5. The invention may be applied with DCHPv4 and DHCPvδ . It is obvious to a person skilled in the art that with the advancement of technology, the basic idea of the invention may be implemented in various ways. The invention and its embodiments are thus not limited to the examples described above, instead they may vary within the scope of the claims.