At the lowest (logical) level, network links look like serial lines. In this chapter we address how packet structures are built on top of serial lines, via encoding and framing. Encoding determines how bits and bytes are represented on a serial line; framing allows the receiver to identify the beginnings and endings of packets. We then conclude with the high-speed serial lines offered by the telecommunications industry, T-carrier and SONET, upon which almost all long-haul point-to-point links that tie the Internet together are based.
- 4.1: Encoding and Framing
- 4.2: Time-Division Multiplexing
- 4.E: Links (Exercises)