TEPZZ 749 B_T EP B1 (19) (11) EP B1 (12) EUROPEAN PATENT SPECIFICATION

Transkript

1 (19) TEPZZ 749 B_T (11) EP B1 (12) EUROPEAN PATENT SPECIFICATION (4) Date of publication and mention of the grant of the patent: Bulletin 1/09 (21) Application number: (22) Date of filing: (1) Int Cl.: H04W 36/14 (09.01) H04W 80/04 (09.01) H04W 8/26 (09.01) (86) International application number: PCT/EP08/0739 (87) International publication number: WO 09/1331 ( Gazette 09/46) (4) SYSTEMS AND METHODS FOR SELECTING A GATEWAY GENERAL PACKET RADIO SERVICE (GPRS) SUPPORT NODE SYSTEME UND VERFAHREN ZUM AUSWÄHLEN EINES UNTERSTÜTZUNGSKNOTENS DES GATEWAY GENERAL PACKET RADIO SERVICE (GPRS) SYSTÈMES ET PROCÉDÉS DE SÉLECTION D UN NOEUD DE SUPPORT GPRS DE TRANSIT (84) Designated Contracting States: AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MT NL NO PL PT RO SE SI SK TR (43) Date of publication of application: Bulletin 11/03 (60) Divisional application: (73) Proprietor: Telefonaktiebolaget L M Ericsson (publ) Stockholm (SE) (72) Inventors: ROMMER, Stefan S Västra Frölunda (SE) SANDER, Ann-Christine S Västra Frölunda (SE) (74) Representative: Vejgaard, Christian et al Ericsson AB Patent Unit GL Göteborg (SE) (6) References cited: DE-A US-A US-A EP B1 Note: Within nine months of the publication of the mention of the grant of the European patent in the European Patent Bulletin, any person may give notice to the European Patent Office of opposition to that patent, in accordance with the Implementing Regulations. Notice of opposition shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). Printed by Jouve, 7001 PARIS (FR)

2 1 EP B1 2 Description TECHNICAL FIELD [0001] The present invention relates generally to the field of mobile IP. BACKGROUND [0002] Many mobile stations (or "user equipment" (UE)) are now configured so as to be able to obtain access to the Internet (or other IP network) through a variety of access networks. For example, a mobile station may obtain access to the Internet through a non-3gpp defined access network (e.g., a WLAN/WiFi network) and through a radio access network (RAN), such as a 3GPP RAN (e.g., a GSM/EDGE RAN (GERAN), UTRAN, etc.). In the rest of this document we will use Wireless LAN (WLAN) to exemplify a non-3gpp access technology. It should however be understood that other non-3gpp access technologies may be used as well. [0003] When a mobile station accesses the internet using a WLAN access network, the mobile station may make use of a Home Agent (HA), and when a mobile station accesses the internet using a 3GPP access network, the mobile station may make use of a GRPS backbone network, which includes a Serving GPRS Support Node (SGSN) and a Gateway GPRS Support Node (GGSN). 3GPP is defining a solution for IP session continuity when a mobile station moves from accessing the Internet through a WLAN to accessing the Internet though a 3GPP RAN. To facilitate this IP session continuity, it has been proposed to collocate the HA function with the GGSN (e.g., provide a GGSN with software for implementing an HA). [0004] One of the main benefits with combining HA and GGSN into a single node is that it is possible to avoid Mobile IP specific signaling and user plane overhead when a mobile station is accessing the Internet via GPRS. This is accomplished by treating the GPRS access as a "home link" for the mobile station. A "Home link" is a specific case for Dual Stack Mobile IPv6 (DSMIPv6) when the mobile station uses an access where the IP address allocated to the mobile station in that access is equal to the Home Address (HoA) allocated to the mobile station by the DSMIPv6 HA. Corresponding "home link" functionality is present also in other Mobile IP variants such as Mobile IPv6 (MIPv6) and Mobile IPv4 (MIPv4). DSMIPv6 is used in the descriptions of the embodiments but it should be understood that also other variants of Mobile IP may be used. [000] When a mobile station is using GPRS access, DSMIPv6 is not activated and IP access is provided to the mobile station using regular GPRS procedures only. When the mobile station is using WLAN access (e.g., I- WLAN access), the mobile station receives a Care-of Address (CoA) from the Packet Data Gateway (PDG) and connects to the HA function in GGSN/HA using DSMIPv6. The IP address assigned in GPRS (PDP address) is the same as the IP address assigned via DSMIPv6 (Home Address). [0006] With the combined GGSN/HA it is required that the same GGSN/HA entity is selected when the mobile station is using GPRS and I-WLAN. One issue with this is that GGSN selection mechanisms are different from HA selection mechanisms. [0007] GGSN selection in GPRS is done by the SGSN based on an Access Point Name (APN). APN information may be received from the HLR, from the mobile station or be pro-configured in the SGSN. Based on the information received from the mobile station, the HLR or that is preconfigured in the SGSN, the SGSN creates an APN string that is resolved in DNS. In the reply from DNS, the SGSN receives one or more IP addresses to GGSN(s) that support the requested APN. [0008] HA selection for DSMIP6 may be done in different ways. One option specified for I-WLAN mobility is that the mobile station resolves a "HA APN" in DNS. Note that this DNS system is accessible to the mobile station and logically separate from the GPRS core network internal DNS system used by SGSN. In the reply from DNS, the mobile station receives one or more IP addresses to HA(s) that support the requested HA APN. [0009] What is desired are systems and methods for selecting a support node so that the same GGSN/HA entity is selected when a mobile station transitions WLAN access to GPRS access. [00] DE describes that a network layer address of a communication provider server is transformed to a unique identifier for the communication provider server and that the unique identifier is transmitted to a communication terminal. The network layer address of the communication provider server can thus be kept secret from the communication terminal. SUMMARY [0011] In one aspect, the present invention provides a method for selecting a support node (e.g., a GGSN or other support node) as defined by claim 1. In some embodiments, the method includes: obtaining a network address for an agent (e.g., a Home Agent in a mobile IP system); transmitting a request to a name server (e.g., a domain name server or other name server) for a name associated with the network address; receiving from the name server in response to the request a name associated with the network address; initiating a network attachment (e.g., a GPRS attachment); and after initiating the network attachment, initiating a context activation (e.g., a PDP context activation), wherein the step of initiating the context activation comprises transmitting the name to a second support node (e.g., a SGSN). The second support node may be configured to select another support node (e.g., a GGSN) based on the received name. In some embodiments, the step of selecting the other support node based on the received name com- 2

3 3 EP B1 4 prises transmitting a request to a second name server for a network address associated with the name. The second name server may be different than the first recited name server (e.g., the second name server may be a GPRS internal name server). The step of transmitting the request to the name server may be performed prior to the step of initiating the network attachment and The network address may be an Internet Protocol (IP) address. [0012] In another aspect, the invention provides an improved mobile as defined in claim 6. In some embodiments, the improved mobile station that is operable to: obtain a network address for an agent; access a network using the agent; transmit a request to a name server for a name associated with the network address; receive from the name server a name associated with the network address; initiate a network attachment; and after initiating the network attachment, transmit to a support node the name received from the name server. Preferably, the support node is configured to select another support node based on the received name. [0013] In another aspect, the present invention provides an improved communication as defined in claim. In some embodiments, the improved communication system includes: a GPRS network comprising an SGSN, a combined GGSN/HA node, and a first name server; and a second name server, wherein the second name server is configured to map a network address associated with the HA function of the combined GGSN/HA node to a name, and the first name server is configured to map the name to a network address associated with the GGSN function of combined GGSN/HA node. [0014] The above and other aspects and embodiments of the present invention are described below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [001] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate various embodiments of the present invention. In the drawings, like reference numbers indicate identical or functionally similar elements. FIG. 1. illustrates a communication system according to embodiments of the invention. FIG. 2 is a flow chart illustrating a process according to some embodiments for selecting a GGSN. FIG. 3 is a functional block diagram of a mobile station (MS) according to embodiments of the invention. DETAILED DESCRIPTION [0016] In one aspect, the present invention provides systems and methods for selecting a GGSN. [0017] Referring now to FIG. 1, FIG. 1 illustrates a communication system 0 according to an embodiment of the invention. More specifically, FIG. 1 illustrates a mobile station 2 that can access a packet data network (e.g., the Internet or other IP network) through a WLAN AN 6 and through a 3GPP RAN 8 and GPRS network 1. GPRS network 1 includes an SGSN 112, a GGSN/HA 114(e.g., conventional GGSN with HA functionality added), and a domain name server (DNS) 116. A second domain name server 118 is accessible via network 4. [0018] Referring now to FIG. 2, FIG. 2 is a flow chart illustrating a process 0 for selecting a GGSN in the environment shown in FIG. 1. Process 0 may begin in step 2, where the mobile station (MS) 2 obtains an IP address associated with the HA function of the GGSN/HA 114 and accesses the network 4 through the WLAN Access Network 6. For example, MS 2 may establish an IP session with a server 1 connected to network 4. [0019] In step 4, MS 2 transmits to DNS 118 a request for a reverse look up using the IP address associated with the HA function. That is, for example, MS 2 may transmit to DNS 118 a reverse look-up request message that includes the IP address associated with the HA function and causes DNS 118 to use the IP address to look-up in its database a name associated with the IP address. In step 6, DNS 118 returns a name associated with the IP address. The name may be an Access Point Name (APN). [00] In step 8, MS 2 initiates a GPRS attach procedure to connect to network 114. For example, while the IP session with server 1 is still active, MS 2 may have moved out of the coverage area of network 6 and into the coverage area of network 8, thereby causing MS 2 to initiate the GPRS attach procedure. [0021] In step 2, MS 2 initiates PDP context activation (e.g., MS 2 transmits to SGSN 112 an "Activate PDP context" request) and provides to SGSN 112 the name received in step 118 as part of the PDP context activation. [0022] In step 212, SGSN 112 resolves the name (e.g., performs a DNS lookup using the name) and receives one or more IP addresses, each of which corresponds to the GGSN function of the combined GGSN/HA 114. For example, in step 212, SGNS 112 may transmit a network address lookup request to DNS 116, which request includes the name received from MS 2 as part of the PDP context activation. [0023] In step 214, the PDP context activation is completed and the mobile station receives the same IP address for the PDP context as was used as the Home Address in the WLAN access. [0024] In this manner, the SGSN 112 will select the same GGSN/HA entity that was used by MS 2 when MS 2 had Internet access through network 6. [002] Referring now to FIG. 3, FIG. 3 further illustrates MS 2 according to some embodiments of the invention. [0026] As illustrated in FIG. 3, MS 2 includes: (1) a transceiver 2 for transmitting and receiving data; (2) a storage device 4 (e.g., non-volatile memory) for storing, among other things, an name 6 received from the 3

4 EP B1 6 name server 118 in response to a reverse look-up request and software 8 for causing the device 2 to perform the functions described herein and illustrated in the flow chart of FIG. 2. [0027] While various embodiments/variations of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments. Further, unless stated, none of the above embodiments are mutually exclusive. Thus, the present invention may include any combinations and/or integrations of the features of the various embodiments. [0028] Additionally, while the processes described above and illustrated in the drawings are shown as a sequence of steps, this was done solely for the sake of illustration. Accordingly, it is contemplated that some steps may be added, some steps may be omitted, and the order of the steps may be re-arranged The method of claim 1, wherein the step of selecting the combined GGSN/HA (114) based on the received name comprises transmitting a request to a second name server (118) for a network address associated with the name. 3. The method of claim 2, wherein the second name server (118) is different than the first recited name server (116). 4. The method of claim 1, wherein the step of transmitting the request to the name server (116) is performed prior to the step of initiating the GPRS attachment.. The method of claim 1, wherein the step of initiating a network attachment comprises initiating a GPRS attachment, and the step of initiating a context activation comprises initiating a Packet Data Protocol, PDP, context activation. Claims 1. A method in a mobile station (2) for selecting a combined Gateway General packet radio service Support Node/Home Agent, GGSN/HA, node (114) when accessing internet (4) using a Wireless Local Area Network, WLAN, access network and when using a General Packet Radio Service, GPRS, network, the method comprising: obtaining (2), at the mobile station (2) accessing internet (4) using the WLAN access network, a network address for a HA function of the combined GGSN/HA (114); transmitting (4), from the mobile station (2), a request to a name server (116) for a name associated with the network address for the HA function of the combined GGSN/HA (114); receiving (6), at the mobile station (2), from the name server (116) in response to the request, the name associated with the network address; initiating (8), at the mobile station (2), a GPRS network attachment; and after initiating the GPRS network attachment, initiating (2), at the mobile station (2), a context activation, wherein the step of initiating the context activation comprises: transmitting, from the mobile station (2), the name to a Serving GPRS Support Node, SGSN (112); and wherein the SGSN (112) selects the same combined GGSN/HA (114) based on the received name when the mobile station (2) access internet (4) using the GPRS network A mobile station (2) for selecting a combined Gateway General packet radio service Support Node/Home Agent, GGSN/HA, node (114) when accessing internet (4) using a Wireless Local Area Network, WLAN, access network and when using a General Packet Radio Service, GPRS, network, wherein the mobile station (2) is operable to: obtain a network address for a HA function of the combined GGSN/HA node (114), which HA is used by the mobile station (2) to access internet (4) using the WLAN access network; access the internet (4) using the HA; transmit a request to a name server (116) for a name associated with the network address for the HA function of the combined GGSN/HA (114); receive from the name server (116), in response to the request, a name associated with the network address; initiate a GPRS network attachment; and after initiating the GPRS network attachment, transmit to a Serving GPRS Support Node, SG- SN (112) the name received from the name server (116); and access internet using the GPRS network and using the same combined GGSN/HA (114) selected by the SGSN (112) based on the received name. 7. The mobile station (2) of claim 6, wherein the mobile station (2) is configured to transmit the request to the name server (116) prior to initiating the network attachment. 8. The mobile station (2) of claim 6, wherein the name server (116) is configured to map the network 4

5 7 EP B1 8 address to a name. 9. The mobile station (2) of claim 8, wherein the network address is an Internet Protocol, IP, address.. A communication system (0), comprising: a mobile station (2) according to claim 6, and a General Packet Radio Service, GPRS, network comprising an Serving GPRS Support Node SGSN (112), a combined Gateway GPRS Support Node/Home Agent, GGSN/HA node (114), a first name server (116) and a second name server (118), wherein the SGSN (112) is configured to select the same combined GGSN/HA (114) based on the received name when the mobile station (2) access the internet (4) using the GPRS network, wherein the first name server (116) is configured to map a network address associated with the HA function of the combined GGSN/HA node (114) to the name, and wherein the second name server (118) is configured to map the name to a network address associated with the GGSN function of combined GGSN/HA node (114). 11. The communication system (0) of claim, wherein the name servers (116, 118) are Domain Name Servers, DNS. Patentansprüche 1. Verfahren in einer Mobilstation (2) zum Auswählen eines kombinierten GGSN/HA (Gateway-Unterstützungsknoten des allgemeinen paketvermittelten Funkdienstes/Heimatagent)-Knotens (114) bei Zugriff auf das Internet (4) unter Verwendung eines WLAN (drahtloses lokales Netz)-Zugangsnetzes und bei Verwenden eines Netzes des allgemeinen paketvermittelten Dienstes, GPRS, wobei das Verfahren umfasst: Erhalten (2) an der Mobilstation (2), die unter Verwendung des WLAN-Zugangsnetzes auf das Internet (4) zugreift, einer Netzadresse für eine HA-Funktion des kombinierten GGSN/HA (114); Senden (4) von der Mobilstation (2) einer Anforderung für einen Namen, der mit der Netzadresse für die HA-Funktion des kombinierten GGSN/HA (114) assoziiert ist, an einen Namensserver (116); Empfangen (6) an der Mobilstation (2) des mit der Netzadresse assoziierten Namens vom Namensserver (116) in Reaktion auf die Anforderung; Einleiten (8) an der Mobilstation (2) eines GPRS-Netzanschlusses; und Einleiten (2) einer Kontextaktivierung an der Mobilstation (2) nach dem Einleiten des GPRS-Netzanschlusses, wobei der Schritt des Einleitens der Kontextaktivierung umfasst: Senden von der Mobilstation (2) des Namens an einen versorgenden GPRS-Unterstützungsknoten, SGSN (112); und wobei der SGSN (112) den gleichen kombinierten GGSN/HA (114) basierend auf dem empfangenen Namen auswählt, wenn die Mobilstation (2) unter Verwendung des GPRS-Netzes auf das Internet (4) zugreift. 2. Verfahren nach Anspruch 1, wobei der Schritt des Auswählens des kombinierten GGSN/HA (114) basierend auf dem empfangenen Namen ein Senden einer Anforderung an einen zweiten Namensserver (118) für eine mit dem Namen assoziierte Netzadresse umfasst. 3. Verfahren nach Anspruch 2, wobei sich der zweite Namensserver (118) vom ersten erwähnten Namensserver (116) unterscheidet. 4. Verfahren nach Anspruch 1, wobei der Schritt des Sendens der Anforderung an den Namensserver (116) vor dem Schritt des Einleitens des GPRS-Anschlusses ausgeführt wird.. Verfahren nach Anspruch 1, wobei der Schritt des Einleitens eines Netzanschlusses ein Einleiten eines GPRS-Anschlusses umfasst, und der Schritt des Einleitens einer Kontextaktivierung ein Einleiten einer Paketdatenprotokoll, PDP,-Kontextaktivierung umfasst. 6. Mobilstation (2) zum Auswählen eines kombinierten GGSN/HA (Gateway-Unterstützungsknoten des allgemeinen paketvermittelten Funkdienstes/Heimatagent)-Knotens (114) bei Zugriff auf das Internet (4) unter Verwendung eines WLAN (drahtloses lokales Netz)-Zugangsnetzes und bei Verwenden eines Netzes des allgemeinen paketvermittelten Dienstes, GPRS, wobei die Mobilstation (2) ausgelegt ist zum: Erhalten einer Netzadresse für eine HA-Funktion des kombinierten GGSN/HA-Knotens (114), wobei der HA durch die Mobilstation (2) zum Zugreifen auf das Internet (4) unter Verwendung des WLAN-Netzes verwendet wird; Zugreifen auf das Internet (4) unter Verwen-

6 9 EP B1 dung des HA; Senden einer Anforderung an einen Namensserver (116) für einen Namen, der mit der Netzadresse für die HA-Funktion des kombinierten GGSN/HA (114) assoziiert ist; Empfangen eines mit der Netzadresse assoziierten Namens vom Namensserver (116) in Reaktion auf die Anforderung; Einleiten eines GPRS-Netzanschlusses; Senden nach dem Einleiten des GPRS-Netzanschlusses des vom Namensserver (116) empfangenen Namens an einen versorgenden GPRS-Unterstützungsknoten, SGSN (112); und Zugreifen auf das Internet unter Verwendung des GPRS-Netzes und unter Verwendung des durch den SGSN (112) basierend auf dem empfangenen Namen ausgewählten gleichen kombinierten GGSN/HA (114). 7. Mobilstation (2) nach Anspruch 6, wobei die Mobilstation (2) so konfiguriert ist, dass sie die Anforderung vor dem Einleiten des Netzanschlusses an den Namensserver (116) sendet. 8. Mobilstation (2) nach Anspruch 6, wobei der Namensserver (116) so konfiguriert ist, dass er die Netzadresse auf einen Namen abbildet. 9. Mobilstation (2) nach Anspruch 8, wobei die Netzadresse eine Internetprotokoll, IP,-Adresse ist.. Kommunikationssystem (0), umfassend: eine Mobilstation (2) nach Anspruch 6, und ein Netz des allgemeinen paketvermittelten Funkdienstes, GPRS, das einen versorgenden GPRS-Unterstützungsknoten, SGSN (112), einen kombinierten GGSN/HA (Gateway-Unterstützungsknoten des allgemeinen paketvermittelten Funkdienstes)-Knoten (114), einen ersten Namensserver (116) und einen zweiten Namensserver (118) umfasst, wobei der SGSN (112) so konfiguriert ist, dass er den gleichen kombinierten GGSN/HA (114) basierend auf dem empfangenen Namen auswählt, wenn die Mobilstation (2) unter Verwendung des GPRS-Netzes auf das Internet (4) zugreift, wobei der erste Namensserver (116) so konfiguriert ist, dass er eine mit der HA-Funktion des kombinierten GGSN/HA-Knotens (114) assoziierte Netzadresse auf den Namen abbildet, und wobei der zweite Namensserver (118) so konfiguriert ist, dass er den Namen auf eine mit der GGSN-Funktion des kombinierten GGSN/HA- Knotens (114) assoziierte Netzadresse abbildet Kommunikationssystem (0) nach Anspruch, wobei die Namensserver (116, 118) Domänennamensserver, DNS, sind. Revendications 1. Procédé dans une station mobile (2) pour sélectionner un noeud combiné d agent de rattachement/noeud de prise en charge de service radio par paquets général de passerelle GGSN/HA (114) lors d un accès à Internet (4) en utilisant un réseau d accès de réseau local sans fil WLAN et lors de l utilisation d un réseau de service radio par paquets général GPRS, le procédé comprenant de : obtenir (2) au niveau de la station mobile (2) un accès à Internet (4) en utilisant le réseau d accès WLAN, une adresse de réseau pour une fonction HA du GGSN/HA (114) ; transmettre (4) depuis la station mobile (2) une demande vers un serveur de nom (116) d un nom associé à l adresse de réseau pour la fonction HA du GGSN/HA combiné (114) ; recevoir (6) au niveau de la station mobile (2) depuis le serveur de nom (116) en réponse à la demande, le nom associé à l adresse de réseau ; amorcer (8) au niveau de la station mobile (2) un rattachement au réseau GPRS et après l amorce du rattachement au réseau GPRS, amorcer (1) au niveau de la station mobile (2) une activation de contexte, dans lequel l étape d amorce de l activation de contexte comprend de: transmettre depuis la station mobile (2) le nom à un noeud de prise en charge GPRS de desserte (112) ; et dans lequel le SGSN (112) sélectionne le même GGSN/HA combiné (114) sur la base du nom reçu lorsque la station mobile (2) accède à Internet (4) en utilisant le réseau GPRS. 2. Procédé selon la revendication 1, dans lequel l étape de sélection du GGSN/HA (114) sur la base du nom reçu comprend de transmettre une demande à un second serveur de nom (118) d une adresse de réseau associé au nom. 3. Procédé selon la revendication 2, dans lequel le second serveur de nom (118) est différent du premier serveur de nom cité (116). 4. Procédé selon la revendication 1, dans lequel l étape de transmission de la demande au serveur de nom (116) est effectuée avant l étape d amorce du rattachement GPRS. 6

7 11 EP B1 12. Procédé selon la revendication 1, dans lequel l étape d amorce d un rattachement au réseau comprend d amorcer un rattachement GPRS et l état d amorce d activation de contexte comprend d amorcer une activation de contexte de protocole de données en paquets PDP. 6. Station mobile (2) pour sélectionner un noeud combiné d agent de rattachement/noeud de prise en charge de service radio par paquets général de passerelle GGSN/HA (114) lors d un accès à Internet (4) en utilisant un réseau d accès de réseau local sans fil WLAN et lors de l utilisation d un réseau de service radio par paquets général GPRS, dans lequel la station mobile (2) est opérationnelle pour : obtenir une adresse de réseau pour une fonction HA du noeud GGSN/HA combiné (114), lequel HA est utilisé par la station mobile (2) pour accéder à Internet (4) en utilisant le réseau d accès WLAN ; accéder à Internet (4) en utilisant le HA ; transmettre une demande à un serveur de nom (116) d un nom associé à l adresse de réseau pour la fonction HA du noeud GGSN/HA combiné (114), recevoir depuis le serveur de nom (116), en réponse à la demande, un nom associé à l adresse de réseau ; amorcer un rattachement au réseau GPRS ; et après la mort sur rattachement au réseau GPRS, transmettre à un noeud de prise en charge GPRS de desserte SGSN (112) et le nom reçu depuis le serveur de nom (116) ; et accéder à Internet en utilisant le réseau GPRS et en utilisant le même GGSN/HA combiné (114) sélectionné par le SGSN (112) sur la base du nom reçu GPRS comprenant un noeud de prise en charge GPRS de desserte SGSN (112), un noeud combiné de prise en charge GPRS de passerelle/noeud d agent de rattachement GGSN/HA (114), un premier serveur de nom (116) et un second serveur de nom (118), dans lequel le SGSN (112) est configuré pour sélectionner le même GGSN/HA combiné (114) sur la base du nom reçu dans la station mobile (2) accède à Internet (4) en utilisant le réseau GPRS, dans lequel le premier nom de serveur (116) est configurée pour mettre en correspondance une adresse de réseau associé à la fonction HA du GGSN/HA combiné (114) avec le nom et dans lequel le second serveur de nom (118) est configuré pour mettre en correspondance le nom avec une adresse de réseau associée à la fonction GGSN du noeud combiné GGSN/HA (114). 11. Système de communication (0) selon la revendication, dans lequel les serveurs de noms (116,118) sont des serveurs de noms de domaine DNS. 7. Station mobile (2) selon la revendication 6, dans lequel la station mobile (2) est configurée pour transmettre la demande au serveur de nom (116) avant d amorcer le rattachement au réseau. 8. Station mobile (2) selon la revendication 6, dans lequel le serveur de nom (116) est configuré pour mettre en correspondance l adresse de réseau avec un nom Station mobile (2) selon la revendication 8, dans lequel l adresse de réseau est une adresse de protocole Internet IP. 0. Système de communication (0), comprenant : une station mobile (2) selon la revendication 6 et un réseau de service radio par paquets général 7

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11 EP B1 REFERENCES CITED IN THE DESCRIPTION This list of references cited by the applicant is for the reader s convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard. Patent documents cited in the description DE [00] 11