Overview¶
Fast Path PPPoL2TP provides PPPoL2TP in the fast path.
L2TP is a network protocol for encapsulating PPP frames inside L2TP frames. It is defined in RFC 2661.
PPPoL2TP has two distinct stages, the L2TP Session stage and the PPP Session stage.
The L2TP Session stage aims at establishing a tunnel with a LNS, and establishing or terminating a L2TP session. It is handled by the control plane. A L2TP session offers an underlying layer to a PPP connection.
the PPP Session stage is a classical PPP connection running over an established PPPoL2TP session. The handling of this stage is split between Fast Path PPPoL2TP, the Linux kernel and the control plane:
Fast Path PPPoL2TP handles all PPPoL2TP packets with the following properties: - L2TP version is 2 - L2TP tunnel is over IPv4 - L2TP Sequence Numbers are not present - PPP following RFC 1662 - PPP next protocol is either IPv4 or IPv6
the control plane handles all PPP and L2TP control protocols (such as LCP, PAP, CHAP, IPCP or IPv6CP), and all packets with Sequence Number or with a version different of 2,
the Linux kernel performs the encapsulation and decapsulation of possible other dataplane traffic in PPPoL2TP frames.
Features¶
PPPoL2TP dataplane processing (PPP session stage).