(LAPB, HDLC, and PPP):
communications, or both.
provide error detection.)
practically speaking, both sides agree to the same speed, but
there is no check or adjustment of the rates if they are slightly
different. However, because only 1 byte per transfer is sent,
slight differences in clock speed are not an issue. A start bit is
used to signal the beginning of a byte.
speed when using synchronous links.
digital links as an interface to the telephone company in the
United States. Routers typically use a short cable from a serial
interface to a DSU/CSU, which is attached to the line from the
telco with a similar configuration at the other router on the
other end of the link. The routers use their attached DSU/CSU
as the clock source.
twisted-pair wires. Each pair is used to send in one direction,
so a 4-wire circuit allows full-duplex communication.
twisted-pair wire. The pair is used to send in only one direction
at a time, so a 2-wire circuit allows only half-duplex
communication.
1.544Mbps. This can be used with a T/1 multiplexor.
channels. In the United States, one of every 8 bits in each
channel can be used by the telco so that the channels are
effectively 56kbps channels.
64kbps channels.