Asynchronous Communication - Data Link Layer and Higher

Data Link Layer and Higher

Asynchronous communication at the data link layer or higher protocol layers is known as statistical multiplexing or packet mode communication, for example asynchronous transfer mode (ATM). In this case the asynchronously transferred blocks are called data packets, for example ATM cells. The opposite is circuit switched communication, which provides constant bit rate, for example ISDN and SONET/SDH.

The packets may be encapsulated in a data frame, with a frame synchronization bit sequence indicating the start of the frame, and sometimes also a bit synchronization bit sequence, typically 01010101, for identification of the bit transition times. Note that at the physical layer, this is considered as synchronous serial communication. Examples of packet mode data link protocols that can be/are transferred using synchronous serial communication are the HDLC, Ethernet, PPP and USB protocols.

Read more about this topic:  Asynchronous Communication

Famous quotes containing the words data, link, layer and/or higher:

    This city is neither a jungle nor the moon.... In long shot: a cosmic smudge, a conglomerate of bleeding energies. Close up, it is a fairly legible printed circuit, a transistorized labyrinth of beastly tracks, a data bank for asthmatic voice-prints.
    Susan Sontag (b. 1933)

    The lifelong process of caregiving, is the ultimate link between caregivers of all ages. You and I are not just in a phase we will outgrow. This is life—birth, death, and everything in between.... The care continuum is the cycle of life turning full circle in each of our lives. And what we learn when we spoon-feed our babies will echo in our ears as we feed our parents. The point is not to be done. The point is to be ready to do again.
    Paula C. Lowe (20th century)

    After a few months’ acquaintance with European “coffee,” one’s mind weakens, and his faith with it, and he begins to wonder if the rich beverage of home, with its clotted layer of yellow cream on top of it, is not a mere dream after all, and a thing which never existed.
    Mark Twain [Samuel Langhorne Clemens] (1835–1910)

    It is the Late city that first defies the land, contradicts Nature in the lines of its silhouette, denies all Nature. It wants to be something different from and higher than Nature. These high-pitched gables, these Baroque cupolas, spires, and pinnacles, neither are, nor desire to be, related with anything in Nature. And then begins the gigantic megalopolis, the city-as-world, which suffers nothing beside itself and sets about annihilating the country picture.
    Oswald Spengler (1880–1936)