IPv4 PDN router interface

When a cellular port is configured for IPv4 operation, the associated PDN router interface is always an unnumbered interface; therefore, it cannot be directly configured with an IPv4 address. The IPv4 address assigned to a PDN interface must be specified from a loopback interface or learned directly from the cellular network during the cellular network attachment process. An IPv4 address specified from a loopback interface is used in the following ways:

  • as the source IPv4 address for GRE-MPLS packets that are sent over a cellular port

  • as the BGP local-address for BGP sessions over a cellular port

  • as the T-LDP local-lsr-id for T-LDP signaling sessions

An IPv4 PDN router interface can operate in one of three modes:

  • static cellular system IPv4 mode

  • static cellular interface IPv4 mode

  • dynamic cellular interface IPv4 mode

The mode of operation dictates the way in which the IPv4 address is assigned to the PDN router interface and how it is used in conjunction with services.

For information about the types of services supported on an IPv4 PDN router interface and how an IPv4 PDN interface IP addresses is used by services, see Services over the cellular PDN interface.

An IPv4 PDN router interface supports Network Group Encryption (NGE). For information about NGE, see Network group encryption.

An IPv4 PDN router interface supports IPSec secure interfaces. For information about IPSec secure interfaces, see IPSec secured interface over cellular.