This article may be too technical for most readers to understand. Please help improve it to make it understandable to non-experts, without removing the technical details. (July 2020) (Learn how and when to remove this template message)

PPPoX (PPP over X) designates a family of encapsulating communications protocols implementing Point-to-Point Protocol.

Specific implementations:

PPPoE: PPP over Ethernet – which can use 802.1q VLANs
PPPoA: PPP over ATM
PPTP: PPP encapsulated over GRE with a parallel control connection and some optional encryption
L2TP v2 (and its ancestor L2F): PPP sessions multiplexed within tunnels and transported over UDP