PPP

• DOES provide error detection
• DOES NOT provide frame loss detection

Frame Format

PPP frames are variants of HDLC frames.

Flag	Address	Control	Protocol	Payload	FCS	Flag
0x7E	1B	1B	2B	variable (1500B max)	2B	0x7E

• Flag: 0x7E (01111110)
• Address: 0xFF (peer-to-peer, address makes no sense)
• Control: usually 0x03
• Protocol
  • 0x0021 for IP
  • 0x8021 for IPCP
  • 0xC021 for LCP
  • 0xC023 for PAP