Octet-Synchronous PPP
Some channels (ISDN, IS-95) provide PPP with a synchronous octet (byte) stream
No need for bit stuffing (physical layer maintains byte alignment)
Still need frame delimiters and CRCs
- byte stuffing to protect special chars:
- 0x7e -> 0x7d, 0x5e [flag]
- 0x7d -> 0x7d, 0x5d [escape character]
- other special characters can also be escaped as needed:
- 0x01 -> 0x7d, 0x21 [ascii control character]
- c -> 0x7d, (c ^ 0x20) [general rule]