Access Point Name
Access Point Name ( APN abbreviated, often called " access point" ) is the name of the connection point to the GPRS backbone, which allows access to an external packet data network.
Definition
In a GPRS backbone network, the APN is a reference to a GPRS Support Node (GGSN ). Here, each GGSN may possess different access points Links to more packet data networks. Thus the APN also defines, at which the access point and thus to which network a connection for the mobile terminal is to be established.
APN are DNS host name and therefore comparable with FQDN host names on the Internet. But while a FQDN host name specifies a reference to an IP address on the Internet, APN specifies a reference to an IP address in the GPRS backbone, precisely to that of a GGSN. APN are therefore used in many nodes in the GPRS network, so with mobile devices, SGSN, GGSN or HLR / VLR.
Although the term APN is clearly defined in 3GPP 03:03, it is colloquially usually equated with the data network is connected to the mobile terminal. Occasionally, the packet service connection settings are called APN.
Examples
- Internet
- Mywap
- Bigbank intranet
- Mycompany.mnc02.mcc283.gprs
- Web.vodafone.de / wap.vodafone.de
Typically, a user wants a mobile terminal access to the Internet. Other examples are WAP services or Datentunneling in a corporate intranet. The reference names and their scope are determined by the current cellular network or the allocated SGSN.
Operation
When setting up a GPRS or UMTS packet data connection, the mobile terminal informs the SGSN APN. The SGSN determines it by a DNS query in the GPRS backbone ( IP network ) the registered for this APN competent GGSN. After that is established between SGSN and GGSN GTP connection over which data packets are transported from the mobile terminal to the access point and from there to the packet data network.
To ensure data roaming between GPRS networks of different mobile companies following DNS scheme is used for cross-network APN:
The SGSN try this query on the DNS hierarchy in the GPRS backbone to resolve the APN and so to find the appropriate GGSN in foreign networks.