With increasing demand for higher bandwidth and lower latency packet switching, communications providers introduced Frame Relay. Although the network layout appears similar to that for X.25, available data rates are commonly up to 4 Mbps, with some providers offering even higher rates.

Frame Relay differs from X.25 in several aspects. Most importantly, it is a much simpler protocol that works at the data link layer rather than the network layer.

Frame Relay implements no error or flow control. The simplified handling of frames leads to reduced latency, and measures taken to avoid frame build-up at intermediate switches help reduce jitter.

Most Frame Relay connections are PVCs rather than SVCs. The connection to the network edge is often a leased line but dialup connections are available from some providers using ISDN lines. The ISDN D channel is used to set up an SVC on one or more B channels. Frame Relay tariffs are based on the capacity of the connecting port at the network edge. Additional factors are the agreed capacity and committed information rate (CIR) of the various PVCs through the port.

Frame Relay provides permanent shared medium bandwidth connectivity that carries both voice and data traffic. Frame Relay is ideal for connecting enterprise LANs. The router on the LAN needs only a single interface, even when multiple VCs are used. The short-leased line to the FR network edge allows cost-effective connections between widely scattered LANs.

Interactive Media Activity Checkbox: WAN Technologies Frame Relay Upon completing this activity, the student will be able to identify the characteristics associated with a Frame Relay circuit.

Web Links Frame Relay http://www.cisco.com/univercd/cc/ td/doc/cisintwk/ito_doc/frame.htm