Overview

Frame relay is a WAN packet-switching protocol that provides LAN-to-LAN connectivity. It relies on higher-level protocols to do error correction and to request retransmissions if packets are lost or discarded. Frame relay has two strong features: It is economical and efficient. It also provides a single point of network access for multiple LAN-to-LAN connections, which is not true in networks using private links. This feature offers considerable savings on local loop charges. Frame relay also can be implemented using existing bridges or routers. In this chapter we examine the various concepts related to frame relay from both conceptual and technical perspectives.

1. What is frame relay?

   Frame relay, which was originally part of the ISDN standard, is a public WAN packetswitching protocol that provides LAN-to-LAN connectivity. Its name implies what it does, namely, relays frames across a network between two sites.

2. What do you mean it was originally part of the ISDN standard?

   As we noted in Chapter 11, ISDN was developed in the 1970s to eventually replace the public switched telephone network (PSTN). As part of its development, ISDN was designed to provide both voice and data service. Although ISDN was considered a significant improvement to the PSTN, it was still an evolution of the PSTN and hence was circuit-switched. This did not bode well for providing data applications efficiently. If data applications were going to be supported in an efficient manner, then a packet-switching component needed to be included with the ISDN standard. (See Chapter 1 for additional...