you can buy virtual circuits with a guaranteed CIR. Your provider guarantees that this rate will be available as needed. Common CIRs include: 32 Kbps, 64 Kbps, 128 kbps, and 256 Kbps. If you transmit over this speed, you're in danger of losing packets and data. If the carrier's service is not working well, it may show congestion and packet loss, even if you are under your CIR.

See CIR.

Committed Information Rate or CIR in a Frame relay network is the average bandwidth for a virtual circuit guaranteed by an ISP to work under normal conditions. At any given time the bandwidth should not fall below this committed figure. It is usually expressed in kilobits per second (Kbps).