The design of X.25 aimed to provide error-free delivery over links with high error-rates. Frame relay takes advantage of the new links with lower error-rates, enabling it to eliminate many of the procedures used by X.25. The elimination of functions and fields, combined with digital links, enables frame relay to operate at speeds 20 times greater than X.25.
X.25 specifies processing at layers 1, 2 and 3 of the OSI model, while frame relay operates at layers 1 and 2 only.[citation needed] This means that frame relay has significantly less processing to do at each node, which improves throughput by an order of magnitude.
X.25 prepares and sends packets, while frame relay prepares and sends frames. X.25 packets contain several fields used for error and flow control, none of which frame relay needs. 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 .
X.25 has a fixed bandwidth available. It uses or wastes portions of its bandwidth as the load dictates. Frame relay can dynamically allocate bandwidth during call setup negotiation at both the physical and logical channel level.
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