The Free On-line Dictionary of Computing (30 December 2018):

Frame Relay

    A DTE-DCE interface specification based
   on LAPD (Q.921), the Integrated Services Digital Network
   version of LAPB (X.25 data link layer).  A common
   specification was produced by a consortium of StrataCom,
   Cisco, Digital, and Northern Telecom.

   Frame Relay is the result of wide area networking
   requirements for speed; LAN-WAN and LAN-LAN
   internetworking; "bursty" data communications; multiplicity
   of protocols and protocol transparency.  These
   requirements can be met with technology such as optical
   fibre lines, allowing higher speeds and fewer transmission
   errors; intelligent network end devices (personal computers,
   workstations, and servers); standardisation and adoption
   of ISDN protocols.  Frame Relay could connect dedicated lines
   and X.25 to ATM, SMDS, BISDN and other "fast packet"
   technologies.

   Frame Relay uses the same basic data link layer framing and
   Frame Check Sequence so current X.25 hardware still works.
   It adds addressing (a 10-bit Data Link Connection Identifier
   (DLCI)) and a few control bits but does not include
   retransmissions, link establishment, windows or error
   recovery.  It has none of X.25's session layer but adds some
   simple interface management.  Any network layer protocol can
   be used over the data link layer Frames.

   Frame Relay Resource Center
   (http://alliancedatacom.com/framerelay.asp).

   (2000-07-14)