The committed information rate (CIR) bucket is defined by two separate parameters: the CIR rate and the committed burst size (CBS).
The CIR is the maximum number of bits that a port can receive or send during a one-second interval. The rate of the traffic that matches the traffic policing policy cannot exceed the CIR. The CIR represents a portion of an interface's bandwidth, expressed in bits per second (bps), and it cannot exceed the port‘s bandwidth.
CIR-defined traffic that does not use its available CIR accumulates credit up to the amount defined by the CBS. This credit is the number of bytes that can be used to accommodate temporary bursts in traffic that exceeds the CIR.