Editing Frame Relay (section)

==Origin==
Frame Relay began as a stripped-down version of the X.25 protocol, releasing itself from the error-correcting burden most commonly associated with X.25. When Frame Relay detects an error, it simply drops the offending packet. Frame Relay uses the concept of shared access and relies on a technique referred to as "best-effort", whereby error-correction practically does not exist and practically no guarantee of reliable data delivery occurs. Frame Relay provides an industry-standard encapsulation, utilizing the strengths of high-speed, packet-switched technology able to service multiple virtual circuits and protocols between connected devices, such as two routers.<br/>
Although Frame Relay became very popular in North America, it was never very popular in Europe. X.25 remained the primary standard until the wide availability of IP made packet switching almost obsolete.
It was used sometimes as backbone for other services, such as X.25 or IP traffic. Where Frame Relay was used in the USA also as carrier for TCP/IP traffic, in Europe backbones for IP networks often used ATM or [[Packet over SONET/SDH|PoS]], later replaced by [[Carrier Ethernet]]<ref>The Network Encyclopedia about [http://www.thenetworkencyclopedia.com/d2.asp?ref=798 Frame Relay], visited 14 July 2012</ref>

===Relationship to X.25===
{{OSIModel}}
[[X.25]] was an important early WAN protocol, and is often considered to be the grandfather of Frame Relay as many of the underlying protocols and functions of X.25 are still in use today (with upgrades) by Frame Relay.<ref>{{cite web | url = https://searchenterprisewan.techtarget.com/definition/frame-relay | title = Frame relay | publisher = techtarget.com}}</ref>

[[X.25]] provides quality of service and error-free delivery, whereas Frame Relay was designed to relay data as quickly as possible over low error networks. Frame Relay eliminates a number of the higher-level procedures and fields used in X.25. Frame Relay was designed for use on links with error-rates far lower than available when X.25 was designed.

X.25 prepares and sends packets, while Frame Relay prepares and sends frames. X.25 packets contain several fields used for error checking and [[flow control (data)|flow control]], most of which are not used by Frame Relay. The frames in Frame Relay contain an expanded [[link layer]] address field that enables Frame Relay nodes to direct frames to their destinations with minimal processing. The elimination of functions and fields over X.25 allows Frame Relay to move data more quickly, but leaves more room for errors and larger delays should data need to be retransmitted.

X.25 packet switched networks typically allocated a fixed bandwidth through the network for each X.25 access, regardless of the current load. This resource allocation approach, while apt for applications that require guaranteed quality of service, is inefficient for applications that are highly dynamic in their load characteristics or which would benefit from a more dynamic resource allocation. Frame Relay networks can dynamically allocate bandwidth at both the physical and logical channel level.