I know that for PPP to travel in datalink layer 2 (ethernet) , the ppp frames need to get encapsulated in a ethernet frame , thus PPPoE. Is the same case for PPTP too?
do encapsulated packets get further encapsulated in Ethernet frames?
PPTP sits on top of a transport-layer connection, using TCP. As such, PPTP frames are encapsulated in TCP segments, those are encapsulated in IP packets, those in turn in frames for Ethernet, IEEE 802.11, ..., even PP(T)P.
ppp frames need to get encapsulated in a ethernet frame , thus PPPoE
Yes - since PPP is designed for a serial connection, PPPoE extends the protocol for use over Ethernet (as does PPPoA for ATM).
The different PPP variants use different underlying protocols and layers:
- PPP: over serial point-to-point byte-level interface (L1)
- PPPoE: over Ethernet (L2)
- PPPoA: over ATM (L2)
- PPTP: over (byte-stream) TCP (L4)