Overview

Frame relay is a digital voice/data delivery service sent over T-1 circuits running at speeds ranging from 56 Kbps to 1.5 Mbps (full T-1 speed).

Frame relay is an established packet-switched technology, widely used and well understood by telcos. Almost every major long distance and local telephone company offers frame relay, and since the Telecom Act of 1996, so do CLECs. There are tons of applications and products.

Frame relay lets you transmit data, voice or video using variable-length packets known as frames. Frame relay is engineered for building virtual private networks (VPNs).

What is a VPN?

VPNs have been offered by long distance carriers for years, what s different from one to the next is the way the data is sent, and which carrier is sending it. VPNs look like dedicated, point-to-point circuits connecting your offices or branches, except that VPNs aren t dedicated, or point-to-point. You purchase here to there connections and a guaranteed data rate, and every time you make a call the carrier s network switches the calls over the best path for them (based on the carrier s traffic levels, commitments and costs) at that particular time.

Frame Relay Beginnings

Packet-based data transport services have been available since the 1970s.

The private leased-line networks used before packet switching was available were point to point, dedicated circuits. Leased-line networks tended to be over-trunked because providing good service (minimal blocked calls) meant you needed to buy enough physical connections to handle peak demand. Any other time, the circuits are paid...