What are the performance parameters for a Frame Relay connection?

Question

What will be an ideal response?

Answer 1

When organizations contract Frame Relay services from a telecommunications provider such as MCI, Sprint, AT&T, or one of the Regional Bell Operating Companies (RBOCs), the contract specifies parameters by which the connection is expected to function. Terms that appear in the contract may include:
• Access rate-The speed of the line, which indicates transfer rate. Common U.S. access rates are 56 Kps, 64 Kbps, and 128 Kbps, which are provided by Integrated Services Digital Network (ISDN) connections; and 1.544 Mbps, which is provided by T1 connections. Access rate is also known as the local access rate.
• Committed Information Rate (CIR)-The minimum transfer rate that the Frame Relay customer negotiates with the Frame Relay service provider. The service provider agrees to always allow the customer to transfer information at no less than the transfer rate specified by the CIR. This is usually lower than the access rate because the transfer rate may exceed the CIR during short bursts.
• Committed Burst Size (CBS)-The maximum amount of data bits that the service provider agrees to transfer in a set time period under normal conditions.
• Excess Burst Size (EBS)-The amount of excess traffic (over the CBS) that the network will attempt to transfer during a set time period. The network can discard EBS data, if necessary.
• Oversubscription-When the sum of the data arriving over all virtual circuits exceeds the access rate, the situation is called oversubscription. This can occur when the CIR is exceeded by burst traffic from the virtual circuits. oversubscription results in dropped packets. In such a case, the dropped packets must be retransmitted.