PDN-Type AVP (Access Point Name – Public Data Network Type Attribute Value Pair) is a parameter in the telecommunications framework that defines the type of IP address support available for accessing a PDN (Public Data Network). The values specified allow the network to determine the IP version(s) a user equipment (UE) can use for connecting to the PDN. Here’s a detailed breakdown:
- PDN-Type AVP: This parameter is of the Enumerated type, meaning it contains predefined values, each representing a specific configuration for PDN access. These configurations are essential for establishing the type of IP address and, therefore, the network capability that the PDN can provide.
- Defined Values:
- IPv4 (0):
- This value means that the PDN can only be accessed using IPv4.
- If a UE connects to this PDN, it must use an IPv4 address, as IPv6 addresses won’t be supported.
- IPv6 (1):
- This value restricts access to only IPv6 addresses.
- UEs connecting to this PDN can only use an IPv6 address and cannot use IPv4.
- IPv4v6 (2):
- This value indicates that the PDN supports both IPv4 and IPv6 simultaneously, meaning dual-stack support.
- UEs with dual-stack capability (i.e., capable of handling both IPv4 and IPv6) can connect to this PDN using either IP version or both, depending on their configuration and network requirements.
- IPv4_OR_IPv6 (3):
- This value provides flexibility, allowing access through either IPv4 or IPv6 but not simultaneously (no dual-stack support).
- Important: UEs won’t request this configuration directly, as they request access based on their own IP capability (IPv4 only, IPv6 only, or IPv4v6). Instead, this value is typically used for network management purposes.
- Specifically, it serves as an authorization mechanism in the APN subscription context between the HSS (Home Subscriber Server) and MME (Mobility Management Entity), allowing network administrators to control and restrict PDN access.
- IPv4 (0):
For more details, take a look at ETSI TS 129 272, clause 7.3.62 PDN-Type
Note: Some PDNs are accessible without requiring IP. These are designated by a specific PDN type indicator within their APN configuration settings (refer to clauses 7.3.204 and 7.3.232 for examples).