Frame Relay is a Consultative Committee
for International Telegraph and Telephone (CCITT) and American
National Standards Institute (ANSI) standard that defines a process
for sending data over a public data network (PDN). It is a high
performance, efficient data technology used in networks throughout the
world. Frame Relay is a way of sending information over a WAN by
dividing data into packets. Each packet travels through a series of
switches in a Frame Relay network to reach its destination. It operates at the physical and data link layers of the
OSI reference model, but it relies on upper-layer protocols such as
TCP for error correction. Frame Relay was originally conceived as a
protocol for use over ISDN interfaces. Today, Frame Relay is an
industry-standard, switched data link-layer protocol that handles
multiple virtual circuits using High-Level Data Link Control (HDLC)
encapsulation between connected devices. Frame Relay uses virtual
circuits to make connections through a connection-oriented service.
The network providing the Frame Relay
interface can be either a carrier-provided public network or a network
of privately owned equipment, serving a single enterprise. A Frame
Relay network can consist of computers, servers, etc. on the user end;
Frame Relay network devices such as switches, routers, CSU/DSUs, or
multiplexers. As
you have learned, user devices are often referred to as data terminal
equipment (DTE), whereas network equipment that interfaces to DTE is
often referred to as data circuit-terminating equipment (DCE), as
shown in Figure
.
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