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.