In the alternative synchronous systems, a whole frame or block of data is sent as a single unit, with a synchronising preamble of a few bytes. This has much lower overhead, and is by far the most common in "leased-line" data links, see later. We saw an example of this in the Ethernet/802.3 frame format in the previous lecture.
Lecture 14: Point-to-Point Data Links | Copyright © 2004 P.Scott, La Trobe University Bendigo. |