Another is that multiple services requiring a variety of quality of service guarantees can be provided simultaneously. ATM user traffic must be segmented into cells, transmitted, and then reassembled back into its original form. This process is done in a standardized way and the hardware which provides this interface capability is relatively new and typically more expensive than frame relay hardware. Frame relay service from public carriers is available worldwide. Its reliability and effectiveness have been demonstrated since the first networks were established in 1991.
Frame relay is popular for a variety of reasons.
It is a relatively inexpensive way to interconnect multiple LANs when compared to leased lines, yet it provides good performance for LAN applications. And, it is less process intensive than X.25, resulting in higher network throughput with lower delay than X.25. DXI, FUNI and frame relay have similar frame structures. As shown in Figure 1, the DXI header and FUNI header within the frame are identical to each other, but are different from the frame relay header. Switch The CN bit performs the same function as the frame relay FECN bit.