Hi, Sprout!
The Internet Protocol Control Protocol (IPCP) of PPP can obtain the IP address of the peer device. Even if the IP addresses of the two ends are on different network segments, they can ping each other.
IPCP is a Network Control Protocol (NCP) for establishing and configuring Internet Protocol over a Point-to-Point Protocol link. Through IPCP, a PPP endpoint can request a specific IP address from its peer (Static negotiation). It can also ask the peer to suggest an IP address by requesting the address 0.0.0.0 (Dynamic negotiation).