Access point name

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An Access Point Name ( APN , also “ Access Point ”) is the name of the gateway between a backbone of a cellular network (e.g. GPRS , 3G or 4G ) and an external packet-based data network, often the public Internet .

definition

In a GPRS backbone network, the APN is a reference to a Gateway GPRS Support Node (GGSN) . Each GGSN can have links to several packet data networks via different access points . The APN also defines to which access point and thus to which network a connection for the mobile device is to be established.

APN are DNS host names and are therefore comparable to FQDN host names on the Internet. However, while an FQDN host name specifies a reference to an IP address in the Internet, an APN specifies a reference to an IP address in the GPRS backbone, precisely that of a GGSN . APN are therefore used in many nodes in the GPRS network, such as mobile terminals, SGSN , GGSN or HLR / VLR .

Although the term APN is clearly defined in 3GPP 03.03, colloquially it is usually equated with the data network to which the mobile device connects. The packet service connection settings are also sometimes referred to as APN.

Examples

  • Internet
  • mywap
  • bigbank intranet
  • mycompany.mnc02.mcc283.gprs
  • web.vodafone.de / wap.vodafone.de

Typically, a user of a mobile device wants access to the Internet. Further examples are WAP services or data tunneling into a company's intranet . The reference names and their area of ​​validity depend on the current cellular network or the assigned SGSN .

functionality

When a GPRS or UMTS packet data connection is set up, the mobile terminal informs the SGSN of the APN. The SGSN then uses a DNS query in the GPRS backbone (IP network) to determine the responsible GGSN entered for this APN . A GTP connection is then established between SGSN and GGSN , via which the data packets are transported from the mobile device to the access point and from there to the packet data network.

In order to ensure data roaming between the GPRS networks of different cell phone companies , the following DNS scheme is used for cross-network APN:

<APN> .mnc <MNC> .mcc <MCC> .gprs

The SGSNs try to resolve the APN by querying the DNS hierarchy in the GPRS backbone and thus to find the responsible GGSN in foreign networks.

Web links

Individual evidence

  1. ↑ a b 3GPP 03.03