Question: What is the purpose of the DHCPDISCOVER message sent by the P-GW to the external DHCPv4 server in the context of IPv4 address allocation and parameter configuration?
Option 1: To request the lease period (T1) and time-out time (T2) from the external DHCPv4 server.
Option 2: To acknowledge the address allocation and receive the configuration information from the external DHCPv4 server.
Option 3: To initiate the IPv4 address allocation process and discover available DHCPv4 servers.
Option 4: To renew the lease period of an already allocated IPv4 address.
Explanation: The DHCPDISCOVER message is sent by the P-GW to initiate the IPv4 address allocation process and discover available DHCPv4 servers. This message is used to request an IP address and configuration parameters from the external DHCPv4 server, as specified in RFC 2131.