PPP
Frame format similar to HDLC
Multi-protocol encapsulation, CRC, dynamic address allocation possible
- key fields: flags, protocol, CRC (fig 2.3)
Asynchronous and synchronous communications possible
Link and Network Control Protocols (LCP, NCP) for flexible control & peer-peer negotiation
Can be mapped onto low speed (9.6Kbps) and high speed channels (SONET)