Chapter 15. Frame Relay
Frame Relay is a Layer 2 (data link) wide-area networking (WAN) protocol that operates at both Layer 1 (physical) and Layer 2 (data link) of the OSI networking model. Although Frame Relay internetworking services were initially designed to operate over Integrated Services Digital Network (ISDN), the more common deployment today involves dedicated access to WAN resources.
ISDN and Frame Relay both use the signaling mechanisms specified in ITU-T Q.933 (Frame Relay Local Management Interface [LMI] Type Annex-A) and American National Standards Institute (ANSI) T1.617 (Frame Relay LMI Type Annex-D).
Frame Relay is considered to be a more efficient version of X.25 because it does not require the windowing and retransmission ...