| 摘要 |
A method for searching for a GGSN(Gateway GPRS Support Node) IP address in an SGSN(Serving GPRS Support Node) is provided to seamlessly offer services by enabling an SGSN to store a GGSN IP address for each APN(Access Point Name) internally so that a GGSN IP address for a specific APN can be confirmed even though a fault occurs in a DNS server. An SGSN acquires GGSN IP addresses for APNs from a DNS server and stores them in a cache(101). The SGSN stores time-elapsed GGSN IP addresses in its internal storage medium among the GGSN IP addresses stored in the cache(102). The SGSN periodically updates the GGSN IP addresses, stored in its internal storage medium, through the DNS server(103). If an APCQ(Activation PDP Context reQuest) message is received from a mobile station(104), the SGSN searches the cache for a GGSN IP address corresponding to the APN contained in the APCQ message(105). If the SGSN failed in obtaining the GGSN IP address from the cache(106), the SGSN asks the DNS server about the GGSN IP address(107). If any result is not received from the DNS server(108), the SGSN searches its internal storage medium for the GGSN IP address(109). If the GGSN IP address is acquired from the cache, the DNS server or the internal storage medium, the SGSN transmits a CPCQ(Create PDP Context reQuest) message to the GGSN(112).
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