High performance PPTP/L2TP/SSTP/PPPoE/IPoE server for Linux (mirror of https://github.com/accel-ppp/accel-ppp.git) https://git.amelek.net/accel-ppp/accel-ppp.git/atom?h=sstp-ppposeq 2026-08-02T20:06:01+00:00 2026-08-02T20:06:01+00:00 Vladislav Grishenko themiron@mail.ru 2026-07-30T10:48:55+00:00 urn:sha1:f2606293c1007aa68a8bcf1e92ae3d64e250eadb A pty is a byte stream, so the tty flip buffer merges frames written back to back and sstp has to re-delimit them with async HDLC escaping and a CRC-16 FCS. On a 1452-byte payload that is ~3600 ns per frame, most of it spent on the FCS. PPPOSEQ is a pppox protocol whose socket is the ppp endpoint itself, so one datagram is one frame and no framing is needed at all. The same payload takes ~380 ns per frame, about 9 times less. Requires kernel 2.6.37, the first with PX_MAX_PROTO 3, whose remaining slot it claims. Supported kernels are from 2.6.37 to 7.2. The new ppp-mode option selects the transport; auto, the default, falls back to async when the module is unavailable, so hosts with prebuilt kernels are unaffected. PPP_SYNC is removed, being disabled and unfixable over a pty: frame boundaries cannot be recovered from the stream, and coalescing cannot be prevented since frames arrive from the network stack.